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EyeLink 1000 User Manual

1. o o o ed Q 2 ed Toggle Ellipse and Centroid pupil center position algorithm Select sampling rate of EyeLink recording Toggle search limit box on or off SHIFT and If search limits are enabled these keys can be used to move cursor keys the position of the search limits lt gt f or U ALT and If search limits are enabled these keys can be used to adjust cursor keys the size and shape of the search limits lt gt f or U Perform camera position autodetect mirror mount Toggle lock tracked eye button Desktop Mount Video Overlay Only Video overlay configuration 2 3 4 Calibrate Screen E L F rack Toggle Pupil only or Pupil CR mode selection may be locked 2 3 4 1 Calibrate Screen Purpose Calibration is used to collect fixation samples from known target points in order to map raw eye data to either gaze position or HREF data Targets are serially presented by the Display PC The participant fixates each while samples are EyeLink 1000 Host Application 2005 2009 SR Research Ltd collected and feedback graphics are presented on the Host PC display The calibration is automatically checked when finished and diagnostics are provided Calibration should be performed after Camera Setup and before Validation Validation provides the experimenter with information about calibration accuracy The zoomed and global views of the camera image along with pupil and CR
2. X 92 L3 2005 2009 SR Research Ltd 4 4 8 Pupil Size Data isses sse eea senes nnn nn arn n nhan sana ase sa aa asas aa as ana 95 AAA POT DU t c 95 2 880 E M 96 Birt I cce m 96 LC NMEPIU UU 96 4 5 8 Eye Movement Eventis eese esee sese ases nna sa sna sa aan sh ananas aaa 97 4 6 Melting File CONELODES cos conces oque vuoto otutvodieduecusa uus ipenda 101 aod ATID OA t 101 02 EVT A uniche oa saa ce ce cas UN REM IM ME NM MM E 101 463 EV CNT VV DCS 102 Sor TOMO Whe GCG iui erent ene E EEA 103 ko US Ane hl cc serene enn rer nn E E mere eee ee 103 BS VCC Bile WORM AG eese eA nu MEINER 104 49 7 ASC FIO STUCIUTO sipiris r se E E EEEO E O 104 402 Sample Line FOUmal acecssctesiosstensexsantisssseskeexisuo eii dian oe dide Mt UHR KU Rule MC dtu 105 4 9 3 LU PE PIQUE 108 4 9 4 Data Specification LINCS ccccccsssceccssseeccnsenseccnsesescnscusescnsausncessensesensanssess 110 4 10 Processing ASC DUCCNCR TNT 111 5 VSM CGIE e E E 113 Dl Ma NANO aera bro EEEE OE N E EE E E EEE 113 0 2 Storage dand Transportation ee eoocs oui a eI PIeRUE RIXA EO STIRdIIdeS EPIS 113 6 Important Information EE oO Lo S S S 114 MEO en ene E ee eee eee ee E ae ee en tr Tey 114 6 1 1 Eye Illumination Safety eise essen enean nnns 114 0 2 SSEFIVIGIHP
3. DIAMETER Ewent Revert to Last Eumentz amd Data Processing Load Defaults TE p Ege Event Bata TRE WHET Gaccade Sensitivity ACRE HIGH File Sample Filter OFF STD Link finalog Filter Ol fina log Dutput Dat ort Haw Figure 2 4 Set Options Screen 2 3 2 2 Set Options Screen Main Functions Calibration Tupe E m HH E Select the Calibration Type for recording The more locations sampled covering the greatest space the greater the accuracy that can be expected Here a nine point calibration is selected Note that not all Calibration Types are available using the EyeLink Remote option Keyboard Shortcuts C alternates between Calibration Type selected Select the delay in dad SE j1888 milliseconds between calibration or validation targets if automatic target detection is active Force Manual Accept is disabled Keyboard Shortcuts P alternates between Pacing options z Randomize the calibration and validation Randomize Order target presentation order Keyboard Shortcuts R toggle Randomize Order on off Repeat First Point Redisplay the first calibration or validation target As this is typically amongst the poorest samples obtained toggling this option on is recommended Keyboard Shortcuts 1 toggle Repeat First Point on off EyeLink 1000 Host Application 2005 2009 SR Research Ltd PETCIUMISIIE ETT If enabled requires manual pressing the p spaceb
4. Exit Setup Click to return to the screen visited prior to the Camera Setup screen Keyboard Shortcuts ESC exit Camera Setup EyeLink 1000 Host Application 2005 2009 SR Research Ltd Of f line Click to go to the Offline screen Keyboard Shortcuts ESC go to Offline screen Output Record Click to go to the Output screen from which a Recording session can be conducted This is most useful when using the EyeLink 1000 in standalone mode Keyboard Shortcuts O go to Output screen set Options Click to go to the Set Options screen Keyboard Shortcuts S go to Set Options Help F1 Click Help F1 to access the online help page for Camera Setup All available key shortcuts are listed on the Help screen Keyboard Shortcuts F1 open Help screen Calibrate Click to go to the Calibrate screen After setting up the camera and adjusting thresholds EyeLink 1000 and EyeLink 2000 or biases EyeLink Remote you need to calibrate the system Keyboard Shortcuts C go to Calibrate screen Validate Click Validate to go to the Validate screen Validation shows the experimenter the gaze position accuracy achieved by the current calibration parameters Validation should be run after a calibration has been performed Keyboard Shortcuts V go to Validate screen Drift Check Or Click to go to the Drift Check screen A Drift Check Correct is recommended be
5. 7 3 2 Connections to Analog Card The analog card is supplied with a connection cable and screw terminal connection board Analog outputs and digital inputs and outputs are available from this card see the document included with the screw terminal board for which terminals correspond to the analog outputs digital inputs and outputs and ground or 5V It is up to each user to determine how to connect and use the analog output connections for their applications Connections to the analog outputs will depend on what these outputs are connected to typically this is another computer with an analog input card 7 3 3 Noise and Filtering It is very important to make sure these connections are made in a way that does not introduce noise into the data so connections between the analog output terminals and the analog input terminals must be as short as possible If the analog input device does not have filters it may be helpful to add a conditioning filter to each analog connection A 470 ohm resistor between the output and input and a 0 1 microfarad capacitor from the input to ground will filter out most noise sources while not affecting the analog signals this is a 3 4 KHz low pass filter which should settle to 1 in 220 microseconds 7 4 Digital Inputs and Outputs The digital ports are configured by the EyeLink software with AO A7 and BO B7 as inputs and CO C7 and DO D7 as outputs A digital only card is available when analog output is
6. TRACKED CR ee ile none ze lected IGE MOT at a kh Lie Pane PURTLABLE x pta 2 ELCLADATAYSDENO EDF Figure 2 9 EyeLink 1000 Output Screen 2 3 7 2 Output Screen Main Functions Click to go to the Previous screen Keyboard Shortcuts ESC Previous Screen p Click to go to the Camera Setup screen Keyboard Shortcuts ESC Camera Setup Wen Dee Click to go to the Set Options screen Keyboard Shortcuts S go to Set Options screen Help F1 Click to access the online Help page for Camera Setup Keyboard Shortcuts F1 opens Help screen emn Click to begin recording EyeLink data to open EDF file Keyboard Shortcuts ENTER or O Record pen File Click to open writing to data file closes any open file Keyboard Shortcuts F Open File Close File Close open EDF file Keyboard Shortcuts X Close File Add message to EDF file Keyboard Shortcuts M insert a message in current file EyeLink 1000 Host Application 2005 2009 SR Research Ltd 2 3 7 3 Output Screen Key Shortcuts ENTER or O 2 3 8 Record Screen 2 3 8 1 Record Screen Purpose The Record screen allows direct access to initiating data collection The user can choose either a Gaze View see Figure 2 10 or Plot View see Figure 2 11 of the Record screen by toggling the Plot View button Durat m n d Uu peen X J HOT P HS n Tra
7. www sr support com forums showthread php t 179 This can be done easily through Windows Explorer Be sure to back up e g duplicate your existing host ELCL EXE directory from the EYELINK hard drive partition before upgrading to the latest host software You will need to copy the SCD file for your camera from your old ELCL EXE directory to the new ELCL EXE directory Should you accidentally destroy your SCD file a copy should be safely stored on the CDs you received with your EyeLink 1000 An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd 4 The height of the Display PC monitor should be set so that when the participant is seated and looking straight ahead they are looking vertically at the middle to top 75 of the monitor Ideally the Desktop Mount should be about 60 cm from the subject s eyes this will translate into an eye screen distance of about 70 cm with the Desktop Mount placed right in front of the Display PC monitor with no extra space between them The Camera Screw of the Desktop Mount should be aligned with the horizontal center of the monitor For maximum eye tracking range the Mount should be raised so that the top of the illuminator is parallel with and as close as possible to the lower edge of the visible part of the monitor without blocking the subject s view of the screen To keep the viewing distance relatively constant throughout a recording session a comfortable stable chair for th
8. 2005 2009 SR Research Ltd 3 2 1 Tower Mount Participant Setup Monocular Check the position of the eye selection knob on the tracker Tower to see whether this matches the eye selection on the Camera Setup screen Loosen the knob turning counterclockwise move the selection knob to the left if you plan to track the left eye and to the right if you plan to track the right eye and CERES a pu E gems rever Cue thot ameraLink Cable ia j 77 E B if E j f A T A N f i N Y D illuminator Cables ip a h d ji Focusing Arm M ye Selechon Knob Miror Angle BAdjustment Knob e x P i j 1 E hk pi x orehead Rest PAdjuistment Knob unrest Hernghl Adjustment Knob Padded Chinrest Chinrest Position djustment Knob lable Clamp Figure 3 2 Parts of the EyeLink 1000 Tower Mount then tighten the knob Click on the Camera Position Detect button on the Camera Setup screen to check whether the correct eye is highlighted If the eye highlighted on the Camera Setup screen does not match the eye selection knob position on the tracker device you should ensure that the two illuminator cables that come out of the left side of the Tower are connected properly to the left side of the EyeLink 1000 high speed camera the cable marked with R should be plugged to the port marked with an R and the one with L to the r
9. 3 2 7 1 Monocular Long Range Subject Setup After setting up the Long Range Mount s position including pointing the Camera and aligning the Camera and Illuminator find a subject to track This section will cover fine tuning the camera setup and calibrating your subject 1 Check the camera image in the global view If the camera image is vertically flipped this can be corrected by pressing the button to the right of the global camera view If the camera image is horizontally flipped this can be corrected by pressing the button on the left to rotate the camera image 90 at each step and then click on the vertical flip button Figure 3 16 Adjusting the Orientation of the Camera Image 2 For monocular eye tracking make sure the eye to be tracked appears in the center of the global view as in Figure 3 16 the untracked eye may appear near the edge or outside of the camera view depending on the lens used Note that when monocularly tracking the camera should ideally have only the image of the eye to be tracked in its view with the non tracked eye off the camera image If this is not the case there is a risk that the eye tracker will switch the eye being tracked This can be prevented by turning search limits on the USE SEARCH LIMITS button on the Host PC but initial camera placement with only one eye visible will guarantee that inadvertent switching of the tracked eye will not occur Now move the Host PC mouse curso
10. 57 aS cnpub port input data mask OxFF use all bits 7 4 1 Analog Data Output Assignments Eye Channels DACO DAC1 DAC2 DAC3 DAC4 DACS tracking available mode Hedge Monocular e x Y Y I A ee rer ee ee seE Tet Binocular 6 et X env ene Right Binocular 6 J rightX right Y right P Binocular Binoculr 6 leftX leftY leftP right X right Y right P left right Monocular 4 x Y TP Binocular _ Monocular 4 letX leftY right X rigtY Left Binocular 4 leftX lefty Right Binocular 4 rightX righty Binocular Binocular 4 leftX leftY right X right Y Table 3 Analog Channel Data Assignments for the EyeLink 1000 hardware The EyeLink 1000 hardware outputs analog voltages on 3 to 6 channels depending on the mode of operation monocular or binocular and the analog card configuration The monocular analog output configuration set by the analog binocular mapping command in the ANALOG INI file should be used in most cases as it assigns the eye being actively tracked to the first 3 channels When binocular mode is selected left and right eye data is assigned to fixed channels The analog channel assignments may also be limited to 4 channels using the analog force 4channel configuration variable in ANALOG INI This allows operation with binocular data when few analog inputs are avai
11. esses rennen 123 GeO UO SIZe DI A e Ee iistata ten cud IN TUTE SERM IUS E SR RUP ET REM EIU 124 1 0 unebuse and Data SLO DC eccriene da mI PME IPM IPIE CEMET 124 ox SVOE DUTINU SEE 124 7 6 2 Oversampling and Toggle Strobe eese esee 125 ES 2005 2009 SR Research Ltd List of Figures Figure 1 1 Typical EyeLink 1000 Configuration Tower Mount 2 Figure 1 2 EyeLink 1000 Desktop Mount with Camera Level and Angled 6 Figure 1 3 EyeLink 1000 Tower Mount cee cece ee ee ehe eene hehehe 6 Figure 1 4 EyeLink 1000 Primate Mount and Diagram of a Typical Setup 7 Figure 1 5 Eyelank 1000 LCD Arm MOUNT scesscsscsscuccaraieracvensianteiecemieteaest ee aiess 7 Figure 1 6 Typical EyeLink 1000 Long Range Mount Configuration 8 Figure 2 1 Booting into the EyeLink Partition cece eee ece eee eeeeeeeenenees 12 Figure 2 2 EyeLink 1000 Host PC Application Overview esses 14 Figure 2 9 OMNE JL SELL cone ne a ee rae ee ne re eee 14 Figure 2 4 Set Options Screen 3 icicuwseessesensecusarsevnsshenedacsewraphanvemgabeee sen M ue RES 16 Ligure 2 5 Camera Del SEPEOIT scseestemitens docetur epp eat tees auerewmeseetn ctee ts 23 Pieiire 2 6 Calibrate JSCEOE TT socenii exhi ioir mue Moon Ud d eati ERR ASEE ERE dente UE 28 Piette 2 75 Validate CLC isror ake or R EEE 30 Figure 2 8 Drift Check Drift Correct Screen sssseesssssesss
12. HV13 calibration type should be used for best calibration accuracy Press the Set Options button from the Camera Setup screen to display the Set Options screen Check to ensure that the following options are selected for practice e Calibration type 9 point grid the EyeLink Remote has fewer calibration grid options than some other modes e Randomize target order YES e Auto trigger pacing 1000 msec Press the Previous Screen button when done to return to Camera Setup Begin calibration by pressing the Calibrate button from the Camera Setup menu A calibration target will appear on both the Host PC display and the Display PC monitor The subject display is drawn by the TRACK EXE application in response to commands from the EyeLink tracker The Host PC screen will also display the raw pupil position as a moving colored circle and a thresholded image A status bar at the bottom right of the display reports the progress of the calibration The pupil position cursor will jump about when the subject looks about on the display and becomes still when properly fixating the calibration target Instructing the subject to carefully look at the white spot in the middle of the black calibration target will help improve fixation stability Head movements during calibration should be discouraged small head movements are corrected but large movements will severely degrade calibration accuracy due to distortion of the calibration data pa
13. If either is above threshold a saccade signal is generated The parser will check that the saccade signal is on or off for a critical time before deciding that a saccade has begun or ended This check does not affect the recorded time of the saccade start or end but adds some delay to the real time events sent through the link During each saccade or fixation data is collected on velocity position and pupil size At the end of the saccade or fixation this data is used to compute starting ending and average position pupil size and velocity as well as peak velocity Velocity data is also converted into units of degrees per second using real time resolution information This data is then used to create events which are sent over the link and or recorded in an EDF file See the section 4 5 3 Eye Movement Events for more information on events 4 3 2 Parser Limitations The EyeLink 1000 parser was designed for on line low delay identification of saccades and blinks Detection of very small saccades may require off line processing as the special filtering and computation of global velocity cannot be performed on line In smooth pursuit research the parser is less sensitive to small back up saccades opposite to the direction of pursuit than forward saccades due to the low peak velocity of back up saccades The parser only looks ahead in the data a short time to compute velocity and acceleration This limits the data checking the parse
14. Loosen both the Lock knob on the Desktop Mount adjust the tilt of the camera so that the intended eye image appear in the center vertically of the global view of the camera image and then tighten both the Friction knob An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd and the Fest Lock knob to keep the camera in position Also watch out the position of the dotted line so that it is aligned with the bridge of the nose If the dotted line does not appear horizontally centered move the Desktop Mount to the left or right or rotate the angle of the Desktop Mount slightly Important even if the binocular mount is used for monocular eye tracking the dotted line should also be aligned with the center of the face PF 23 Camera Setup TEP IP Link 3 Labi ar are eMe e LL ka b DEINE AS Tracking Mode rusin siege Rate E EC Pupil Tracking Pupil 71 CR H zz H 1K tert oi Right nee MEA Figure 3 14 Camera Setup Screen Desktop Mount Angled Binocular Recording IMPORTANT If the camera image is tilted 45 degrees clockwise please check whether the Configuration setting in the Set Options screen is set to Desktop Angled If the camera image is tilted 45 degrees counterclockwise check whether the camera is set to the oblique position on the Desktop Mount In the global view window of the camera image move the Host PC mouse cu
15. MISSING red Target is not present EYEDIST red Target is placed too close to the eye on the vertical dimension ANGLE red Target has too large an angle to be recognized properly When working in the Output and Record screens if the Pupil Size warning is on at least one sample was interpolated by the system and is indicated by Int appearing beside the Pupil label in the Status Panel All status flags remain on for a minimum of 200 msec even if the condition that caused the warning or error to be raised lasted for less than 200 msec 2 5 Mouse Simulation Mode You can use a mouse on the EyeLink 1000 Host PC to simulate an eye to practice calibration and tracking alone or to test experiments during development if a test subject is not available Select Mouse Simulation in the Set Options screen to enable mouse simulation If the mouse does not move the eye position you will need to perform a calibration on the mouse device See section 3 7 Calibration 2 6 Configuration Files and Experiment Directories Most EyeLink 1000 options are configured within the Host application however there are some lower level options that are specified by editing the configuration files INI or by sending commands from the Display PC via the Ethernet link The configuration files are loaded by the EyeLink 1000 from the directory containing the tracker program C ELCL EXE It may be desirable to maintain a number of unique
16. O to 1 0 would cover the full range of the data 0 1 to 0 9 would cover the central 80 of the data and 0 2 to 1 2 would add a 20 margin above and below the expected data range e For raw data the default range is 0 1 to 0 9 because the pupil position will never reach the edges of the camera image It is possible that the scaled and transformed pupil CR data might exceed this range but in general this range will be similar to that of the camera image Raw data should be assumed to be in arbitrary units For HREF data the entire data range is assumed to be 30000 to 430000 This is about 127 This should never be exceeded The default range setting is therefore 0 0 to 1 0 The HREF data may be recovered from the voltage by the following formula HREF voltage minvoltage maxvoltage 2 60000 maxvoltage minvoltage e For gaze position data the data range is scaled to the display coordinates which are 640 by 480 at startup and may be changed via link commands The data range setting is 0 2 to 1 2 allowing 20 extra range for fixations that map to outside the display This extra data range allows for slippage or for identification of fixations outside the display Scaling to recover gaze position data is more complex as the numerical value is partially dependent Appendix A Using the EyeLink 1000 Analog and Digital Output Card 2005 2009 SR Research Ltd on the display coordinates The following formulas do the conversio
17. Returns MISSING DATA 32768 if target is missing The next thirteen fields represent warning messages for that sample relating to the target and eye image processing if no warning for target and eye image first character is M if target is missing second character is A if extreme target angle occurs third character is N if target is near eye so that the target window and eye window overlap fourth character is C if target 1s too close fifth character is F if target is too far sixth character is T if target is near top edge of the camera image seventh character is B if target is near bottom edge of the camera image eighth character is L if target is near left edge of the camera image ninth character is R if target is near right edge of the camera image tenth character is T if eye is near top edge of the camera image eleventh character is B if eye is near bottom edge of the camera image twelfth character is L if eye is near left edge of the camera image thirteenth character is R if eye is near right edge of the camera image Data Files 2005 2009 SR Research Ltd 4 9 3 Event Line Formats Each type of event has its own line format These use some of the data items listed below Each line begins with a keyword always in uppercase and items are separated by one or more tabs or spaces DATA NOTATIONS eye time stime etime dur axp ayp lt Sxp gt lt Syp gt l
18. button or T on the keyboard to remove the threshold color overlay In TRACK EXE you can use keys on either the Display or Host PC to perform all keyboard shortcut operations while the eye image is displayed The camera should be focused by rotating the focusing arm or the wheel on the lens Look closely at the eye image on the zoomed view while adjusting the focusing of the lens until the eye image is clear If a circle CR signal usually colored turquoise or yellow appears near the pupil the best focus will minimize the size this colored circle By default the Illuminator Power level is set to 75 at the recommended distance If the Desktop Mount is placed too further away from the observer or if you find the pupil is not reliably acquired you may consider increasing the illumination level to 10096 Now continue with section 3 3 Setting Pupil Threshold 3 2 7 Long Range Mount Participant Setup Monocular or Binocular The EyeLink 1000 Long Range Mount can be configured to track monocular eye movements at up to 2000 Hz or binocular movements up to 1000 Hz depending on camera licensing An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd The EyeLink 1000 Installation Guide provides information for setting up the Long Range Mount which should only need to be done once for a given setting The user is then instructed to follow the instructions in this section for setting up a particular participant
19. license required Average Accuracy down to 0 15 0 25 to 0 5 typical 0 5 typical Monocular 250 500 1000 2000 Hz Monocular i 250 500 H Sampling rate2 Proca 7 290 500 1000 Hz M lt 1 8 msec SD lt 0 6 msec 1000 Hz M lt 3 0 msec End to End Sample Delay M lt 1 4 msec SD lt 0 4 msec 2000 Hz SD 1 11 msec M lt 1 8 msec SD lt 0 6 msec 1000 Hz M lt 3 0 msec Blink Occlusion Recovery M lt 1 4 msec SD lt 0 4 msec 2000 Hz SD 1 11 msec 0 01 RMS 1000 Hz Spatial Resolution 0 1 RMS 0 02 RMS 2000 Hz Eye Tracking Principle5 Dark Pupil Corneal Reflection Pupil Detection Models Centroid or Ellipse Fitting Ellipse Fitting Pupil Size Resolution 0 2 of diameter i 60 horizontally 32 horizontally Gaze Tracking Range 40 vertically 25 vertically 22x18x20 cm Allowed Head Movements 25 mm horizontal or vertical6 10 denth horizontal x Without Accuracy Reduction UMSO vertical x depth Optimal Camera Eye Distance Fixed at about 38 cm Between 40 70 cm Glasses Compatibility On line Event Parsing Fixation Saccade Blink Fixation Update raw eye position HREF position gaze position pupil size buttons messages digital inputs Eye position cursor or position traces Binocular Recording not available with the LCD Arm Mount 1 Measured with real eye fixations at multiple screen positions on a per subject basis 2 Availability of some sampling rates depends on the
20. summarized below Pressing the on screen Help button or hitting the F1 key will open a screen sensitive Help menu listing all available key shortcuts for that EyeLink 1000 Host Application 2005 2009 SR Research Ltd screen From any screen the key combination CTRL ALT Q will exit the EyeLink Host Application Calibrate 2 Record Figure 2 2 EyeLink 1000 Host PC Application Overview 2 3 1 Offline Screen Offline Link Closed Screcus ome Setup Outputs Record Set Options Help G1 NM LE a E 100059055 Eyulink is AVA LLABLE Copyright 2001 2009 SR Research Lid red trademark of SR Research Ltd Mississauga Ontario Canada E eLink Figure 2 3 Offline Screen EyeLink 1000 Host Application 2005 2009 SR Research Ltd 2 3 1 1 Offline Screen Purpose The Offline screen is the default start up screen for the EyeLink 1000 The main secondary screens can be accessed via the navigation buttons on the right hand side of the screen 2 3 1 2 Offline Screen Main Functions Tn Click to go to the Camera Setup screen Keyboard Shortcuts ENTER Camera Setup Output R d Qutput Record Click to go to the Output screen from which you can start a manual Recording session Keyboard Shortcuts O go to Output screen Click for access to a variety of EyeLink 1000 options and Set Options f settings on the Set Options screen Keyboar
21. threshold values are displayed at the bottom left of the screen The eye to be calibrated as well as the calibration type as defined in the Set Options screen or via the EyeLink API is indicated beside the camera images at the bottom of the screen The calibration status and current calibration target being presented are indicated on the bottom right of the screen To perform a calibration have the participant look at the first fixation point and select the Accept Fixation button ENTER or the Spacebar to start the calibration If Auto Trigger is disabled Force Manual Accept from the Set Options screen is enabled repeat this action after each target fixation Performing one of these actions quickly twice in succession can switch from an automatic calibration to requiring manual acceptance of target fixations at any point into the sequence This can be useful for subjects showing difficulty fixating targets or who inappropriately anticipate new target positions For such subjects pressing the lt Backspace key will successively erase acquired samples and present calibration targets again allowing the operator the ability to intervene when acquired samples are clearly erroneous Calibrate TETAIF Link Open Fixation cir Right Bue nmm STABLE watii Yo point grid Toint 1 of 10 Figure 2 6 Calibrate Screen EyeLink 1000 Host Application 2005 2009 SR Research Ltd 2 3 4 2 Calibrate Screen Main Fu
22. 4 3 8 Other Parameters The EyeLink 1000 PARSER INI configuration file contains other commands that configure the parser These are of several types e Verification delays These set the time in milliseconds that the parser requires a detector output saccadic velocity or acceleration thresholds or missing pupil for blink to be stable before the parser changes its state and sends events to the data file or link These values have been determined empirically and there is little advantage to changing them e Parser filter types Two velocity filters are available fast and slow The fast filter works better in most cases The slow filter is less noise sensitive but increases saccade duration and decreases sensitivity slightly e oaccade extension This is intended to allow the saccade period to include the lower velocity start and end of the saccadic period This is usually disabled as its effect is minor e Internal constants These MUST NOT be changed 4 3 9 Sample Configurations The complete set of commands for the most useful tracker configurations is given below The cognitive configuration is conservative is less sensitive to noise and ignores most saccades smaller than 0 6 The psychophysical configuration is useful for neurological and smooth pursuit research and reports very small saccades It also better estimates saccade durations and average velocities Data Files 2005 2009 SR Research Ltd Cognitive Configura
23. 5 2 Buttons Each button event records a change in state pressed or released 1 or O of up to 8 buttons or input port bits monitored by the EyeLink 1000 tracker Button Data Files 2005 2009 SR Research Ltd ports bits and polarity may be set in the EyeLink 1000 tracker configuration file BUTTONS INI Each button event contains a timestamp in milliseconds of the time the button was pressed and a word of button data This consists of two 8 bit fields recorded as a 16 bit number The lower 8 bits contain the current status of the 8 buttons bit O if off 1 if pressed Each of the upper 8 bits will be set to 1 if its button has changed since the last sample The least significant bit in each byte corresponds to button 1 and the most significant is button 8 Button events are usually recorded at the start of each recording block with all upper 8 bits change flags set to O This allows applications to track the current button state at all times 4 5 3 Eye Movement Events Events are generated by the EyeLink 1000 tracker in real time from the eye movement data stream These provide an efficient record of the data in a form ready to use for most types of eye movement research The use of events simplifies the analysis of sample data as well For example analysis of pursuit gain requires rejection of saccades which are clearly marked in the events Eye movement events are generated in pairs one event at the start of an eye m
24. 7 3 External Camera Setup and Calibration Validation The subject will usually be in different room from the Host or display PCs for Long Range applications such as MEG and MRI so an External Camera Setup and Calibration and Validation procedure has been developed To take advantage of this facility requires the latest version of the Experiment Builder software and EyeLink Development Kit Custom written software will need to be recompiled switching on the External Camera Setup option External Camera Setup is accomplished through the use of response boxes that are configured to trigger the adjustment of thresholds on the Host PC the initiation of Calibration and Validation and the controlling of sampling during calibration and validation Any response box that has a key press as output can be used and the software can be configured to map any key onto a variety of setup functions Discussion of configuring and using the External Camera Setup feature can be found in the latest version of Experiment Builder An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd Now proceed to section 3 3 Setting Pupil Threshold and the rest of the sections for calibration 3 3 Setting Pupil Thresholds The camera image of the eye should now be clear with the pupil centered when the subject looks at the eye image on the subject computer s display The pupil threshold may now be automatically set by pressing the Auto Threshol
25. C 10 90 humidity non condensing Allow components to warm to room temperature before unpacking or use after storage at temperatures below 10 C to prevent condensation 12V 800 mA for camera alone 1 6A when used with 2 illuminators Storage conditions 12V 2A external power supply with 2 5mm coaxial barrel power connector 5 5x2 5x9 5mm Power supply must have EN 60950 UL 950 CSA 22 2 No 950 or other equivalent safety approval with LPS or Class 2 rating FCC Part 15 Subpart B Class A unintentional radiators CISPR 11 1997 and EN55011 1998 Class A 60950 1 ed 1 Safety of ITE Equipment CB test certificate including US Canada and international requirements UL 60950 3rd Edition CSA C22 2 No 60950 00 CAN CSA EyeLink 1000 Camera Power Requirements Electromagnetic compatibility and immunity CC FE Introduction 2005 2009 SR Research Ltd CLASS 1 LED DEVICE IEC 60825 1 Ed 1 2 2001 NOTE This equipment has been tested and found to comply with the limits for a Class A digital device pursuant to part 15 of the FCC Rules These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual may cause harmful interference to radio communications Operation of th
26. DAMAGES In certain instances some jurisdictions do not allow the exclusion or limitation of incidental or consequential damages or the exclusion of implied warranties so the above limitations and exclusions may not be applicable WARRANTY SERVICE For product operation and information assistance please visit http www sr research com and submit a support request or contact a SR Research Ltd Support representative For product repairs please contact your sales representative for appropriate instructions Important Information 2005 2009 SR Research Ltd 6 4 Limited Software Warranty SR Research Ltd warrants that the software disks and CD s are free from defects in materials and workmanship under normal use for one 1 year from the date you receive them This warranty is limited to the original owner and is not transferable The entire liability of SR Research Ltd and its suppliers and your exclusive remedy shall be a replacement of any disk that does not meet this warranty which is sent with a return authorization number from SR Research Ltd This limited warranty is void if any disk is damaged has resulted from accident abuse misapplication or service or modification by someone other than SR Research Ltd Any replacement disk is warranted for the remaining original warranty period or 30 days whichever is longer SR Research Ltd does not warrant that the functions of the software will meet your requirements or th
27. DATA INI file The default parameters specify that data is written to a disk partition called EYELINK and to a root directory called ELCL DATA If this partition directory is not found the data are written to the directory that the ELCL EXE was started from As mentioned above you can specify an experiment specific data directory by copying the DATA INI file to your experiments launch directory and modifying the data drive name and data drive directory parameters copying these commands to your FINAL INI This is a list of all EyeLink configuration files and what they control ANALOG INI BUTTONS INI CALIBR INI COMMANDS INI DATA INI DEFAULTS INI ELCL INI AMTABLER INI BTABLE R INI MTABLE R INI RTABLE R INI and TOWER INI EYENET INI optional analog output hardware interface configures clock strobe control hardware definition of buttons special button functions preconfigured for Microsoft SideWinder Plug amp Play commands used to control the calibration settings lists some useful EyeLink commands for controlling the host application via your own program specifies where EDF files should be written on Host PC controls data written to EDF files and the Ethernet link default settings for all items in LASTRUN INI can be loaded from Setup menu contains commands specific to the EyeLink 1000 series includes other INI files for specific mounts list of mount spe
28. Host PC The EyeLink 1000 Host PC performs real time eye tracking at 250 500 1000 or 2000 samples per second with no loss of spatial resolution while also computing true gaze position on the display viewed by the subject On line detection and analysis of eye motion events such as saccades and fixations is performed These events can be stored in a data file on the Host PC sent through the Ethernet link to the Display PC with a minimal delay or output as analog signals if the analog digital I O card is installed From the Host PC the operator performs subject setup monitors performance and can communicate with applications running on a Display PC The Host PC e houses the EyeLink 1000 high speed frame grabber card Ethernet card and optional analog output digital input card e uses a timing sensitive operating system allowing low variability in EyeLink 1000 Host PC application response e can be used for other purposes when not tracking eye movements Other operating systems such as Windows XP can co exist e functions either as standalone eye tracker or connected to a Display PC through 10 100BASE T Ethernet cable e can operate in a standalone configuration where data can be directed through an optional analog output card and or digitally stored on the hard disk e includes a button box connected by a USB port for highly accurate event recording synchronized with eye movement data e software integrates all needed ey
29. Keyboard Shortcuts CTRL ALT A Abort Trial Instead of showing the gaze cursor plots the x y eye data Plot view being acquired as a function of time Keyboard Shortcuts G toggle between Gaze Cursor and Plot Views z Performs online Drift Check or Drift Correct from the Drift Corr Record screen when Video Overlay mode is enabled This button is not always present Keyboard Shortcuts F perform on line calibration accuracy check 2 3 8 3 Buttons Used in the Plot View The top of the Plot View shows the data type being plotted The Gaze option plots the subject s gaze position in pixel x y display coordinate The Angle options plots the amount of x y eye angle in degrees relative to the center of the screen The HREF plots eye rotation angles relative to the head in HREF coordinate see Section 4 4 2 2 HREF The Raw option plots the raw x y coordinate pairs from the camera The Analog option plots the x y coordinate in voltages output as done with the analog card output The top right lists the speed of plot i e amount of data being plotted in each screen For example Figure 2 11 illustrates a recording screen with a plotting speed of 6 seconds per sweep Each horizontal grid in the plot represents 500 ms worth of data EyeLink 1000 Host Application 2005 2009 SR Research Ltd The scale used in the plot view is dependent on the data type Raw Angle HREF Gaze or Analog s
30. Setup Screen Desktop Mount Throughout the EyeLink 1000 software you can use the Host PC mouse to select options and navigate throughout the tracker screen Almost every button has an equivalent key shortcut The key shortcut mappings available for the currently displayed screen can be accessed via the Help button or by pressing F1 In the Camera Setup screen you can select one of the camera views by pressing the lt and gt cursor keys If an experiment is open on the Display PC like TRACK EXE then pressing the Image Display PC button from the Camera Setup screen will start displaying an image of the selected camera on the Display PC s monitor An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd 3 2 Participant Setup To practice setting up the camera you will need a subject If none is available you can practice this part of the procedure on yourself It is actually easier to practice on yourself first but be sure to repeat with several subjects later Because all keys on the subject keyboard are sent to the EyeLink software by TRACK you can practice calibration and observe your tracked eye position too Since no menus appear on the Display PC you will have to be able to see the Host PC display as well NOTE Ideally to prevent small drifts in thresholds EyeLink 1000 electronics should be powered for about 5 minutes before recording The EyeLink 1000 has several mount and camera combinations
31. Use Search Limits button should be checked for participants wearing glasses This can be used to exclude other regions of the camera image e g frame of the glasses that may otherwise be detected as a pupil CR reflection pattern The disadvantage of using the search limits however is that if the participant completely removes their head from the head support and then puts it back in the head support device the search limits box may not be in the correct location to track the eye This is especially the case when the Move Limits button on the Set Options screen is checked The size of the search limited for the selected eye can be adjusted by pressing ALT and cursor keys on the host keyboard together ALT ff or U to adjust the height ALT lt and gt to adjust the width The position of the search limits can be adjusted with SHIFT and cursor keys In a binocular setup size position of the search limits can be adjusted for each of the eyes separately 3 6 Pupil Tracking Algorithm The EyeLink 1000 implements two pupil tracking algorithms Centroid vs Ellipse Fitting The Centroid mode tracks the center of the thresholded pupil using a center of mass algorithm whereas the Ellipse mode determines the center of the pupil by fitting an ellipse to the thresholded pupil mass In the ellipse mode the host software draws a green ellipse around the pupil area representing the ellipse fitting solution used to determine pupil position For
32. allows for Data Files 2005 2009 SR Research Ltd flexible adaptation to almost any file data configuration Information included in the start events include e Which eye recorded from sample data rate sample data contents Event data contents Event types included Gaze position and velocity prescalers Each block of recorded data ends with one or both of an ENDSAMPLES or ENDEVENTS event This simply terminates the data block and specifies the time that recording ended The text files generated from EDF files by the EDF2ASC translator utility create a simplified form of START and END events A single START or END line is produced for both sample and event blocks which specifies which eye was recorded from and whether samples events or both are present in the following data block Other data is given on following SAMPLES EVENTS PRESCALER etc lines 4 5 3 2 Fixations The on line EyeLink 1000 tracker parser processes eye position data identifying saccades and fixations and compiling data on these conditions For fixations these data include e The time of the first and last sample in the fixation e The eye that generated the event e Average HREF or gaze position data e Average pupil size e Gaze data angular resolution All of this data may appear in the ENDFIX event that terminates the fixation Only the starting data can appear in the STARTFIX event that initiates the fixation In a sorted EDF file or a text AS
33. an Experiment 2005 2009 SR Research Ltd processed with other EDF utilities Information on the EDF file format can also be found in the Chapter 4 of the current document 3 11 Drift Correction Drift Checking The drift correct screen displays a single target to the participant and then measures the difference between the computed fixation position during calibration and the current target Unlike earlier EyeLink I and II eye trackers we have found that correcting the calibration map based on the drift correction result has no significant effect in gaze accuracy Therefore the default drift correction behavior of the EyeLink 1000 system when in pupil CR mode is to only report the calculated fixation error from the drift correction procedure and to not actually adjust the calibration map in any way Therefore the drift correction procedure is better viewed as a Drift Checking procedure in the EyeLink 1000 However the user may opt to perform a drift correction at the beginning of each trial by computing and applying a corrective offset to the raw eye position data This can be done by changing the driftcorrect cr disable command setting in ELCL INI file It is important that before performing a drift correction the subject be instructed to sit still and fixate on the drift correction target carefully If your experiment paradigm permits it is also possible to perform an online drift correction in the middle of trial recording by t
34. and intensity at different distances is also a major consideration L Tower Desktop Mount or LCD Arm Mount Desktop Mount Long Range Mount A ERU Size ponas i 16 mm 25 mm Table 1 Lens Guide for Different Viewing Distances The system may work with some combinations not listed here but has not been extensively tested and may not work for all subjects When deviating from the above recommendations it is incumbent on the researcher to ensure that the system is set up so there is suitable illumination and a good view of the eye to be tracked 2 3 3 Camera Setup Screen 2 3 3 1 Camera Setup Screen Purpose This is the central screen for most EyeLink 1000 setup functions From this screen the view from the camera can be optimized and the pupil and corneal EyeLink 1000 Host Application 2005 2009 SR Research Ltd reflection CR detection threshold or biases can be established The eye to be tracked tracking mode pupil fitting model search limits and display options can be set Calibration Validation and Drift Checking can be performed from this screen Image Thresholds EET AMA 1 Camera Setup E ICE IF k Open SONN sg ire Tite Record set Opt lms oi ir Pupil Tracking Centrotd eee Callhrate irinGE POT 1 inapo Display FT TETTE A vs Validate Crosshairs ce O EVE MOT mondLnis E Figure 2 5 Camera Setup Screen 2 3 3 2 Camera Setup Screen Main Functio
35. any time without notice Important Information 2005 2009 SR Research Ltd 7 Appendix A Using the EyeLink 1000 Analog and Digital Output Card The EyeLink 1000 eye tracking system supports analog output and digital inputs and outputs via a DT334 card The analog card supplies up to 8 channels of 16 bit resolution analog output and 16 bits each of digital input and output The analog outputs may be used to output up to 6 channels of eye and gaze position data for use by non link and legacy applications Digital inputs may be defined as buttons used for controlling the EyeLink tracker or recorded to the EDF data file The outputs may be controlled by out port commands via the link or used by the EyeLink tracker for data strobes and other functions A digital only card the DT3395 is also available This appendix describes how to configure and use the EyeLink 1000 analog and digital outputs While some ideas for input and control of the tracker will be introduced applications are not limited to those introduced here In addition other digital input and output ports may be used including the game ports and the printer port of the EyeLink Host PC 7 1 Analog Data Types Position data and pupil size data are available in several types which are selectable through the EyeLink 1000 Set Options options screen For pupil size either pupil area or pupil diameter may be monitored These are very high resolution measurements with a typic
36. compared to recording to file or digital transfer via the link Typically at least 1 or 2 bits of noise are added by the analog output cabling and re digitization of analog signal transfer The typical EyeLink noise level is 0 01 degree RMS analog data transfer can increase the noise level by a factor of 2 to 20 The EyeLink 1000 system offers integrated data recording to file and digital data transfer through the Ethernet link which has latency comparable to the analog link and does not suffer from the time base resolution and noise degradation inherent in analog systems SR Research Ltd is committed to improving access to the Ethernet link data transfer methods and supplies an analog output option for backwards compatibility with existing experimental systems and as requested by users but does not encourage its use in new systems 7 3 Setting up the EyeLink 1000 Analog Card 7 3 1 Installing Analog Output Hardware The EyeLink 1000 frame grabber PCI card and DLINK Ethernet card should be installed before the analog card can be accessed To install the analog output card open the case of EyeLink Host PC install the card into an empty PCI slot and secure the rear bracket of the card with the bracket screw or card clamp depending on your computer model The EyeLink 1000 tracker software will automatically find and use the analog card Appendix A Using the EyeLink 1000 Analog and Digital Output Card 2005 2009 SR Research Ltd
37. distal end of the chinrest pad The recommended tracking distance is generally from 50 to 55 cm An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd 9 Place the Desktop Mount so that it is aligned to the center of the monitor You may also need to raise the Desktop Mount so that the top of the illuminator should be as close as possible to the lower edge of the visible part of the monitor for maximum eye tracking range 6 Start the EyeLink host application and click Set Options button Check the Configuration is set to Desktop Angled 7 Ensure the lens cap has been removed from the camera by pulling the cap outwards while holding the camera IR Illuminatar Camera Angle Adjustment k y Binocular Camera Rotation h Speed amera Fan Tilt Adjustment Monocular Camera Orientation Binocular Camera Orientation Figure 3 13 Position and Angle of the Camera for EyeLink 1000 Desktop Monocular vs Binocular Mount 8 If you are using the chinrest supplied by the SR Research Ltd please install the forehead rest to the chinrest if you haven t done so yet Ask the subject to be seated Adjust the height of the chair so that the subject is comfortable and his her eye line is aligned to upper half of the monitor Ask the subject to lean her his forehead against the forehead rest and adjust the height of the chinrest so that the subject s chin sits comfortably on the chin rest pad
38. duration fixations that precede or follow a blink These may be artificial or be corrupted by the blink 4 9 4 Data Specification Lines Immediately following a START line several lines of data specifications may be present These lines contain more extensive data than the START line about what data can be expected in the START END block These are most easily Data Files 2005 2009 SR Research Ltd processed by creating a set of flags for each possible data option left eye events right eye samples sample velocity etc clearing these when the START line is encountered and setting the appropriate flags when keywords LEFT VEL etc are encountered in a data specification line e PRESCALER lt prescaler gt If gaze position data or gaze position resolution is used for saccades and events are used they must be divided by this value For EDF2ASC the prescaler is always 1 Programs that write integer data may use a larger prescaler usually 10 to add precision to the data e VPRESCALER lt prescaler gt If velocity data is present it must be divided by this value For EDF2ASC the prescaler is always 1 Programs that write integer data may use a larger prescaler usually 10 to add precision to the data e EVENTS lt data type gt lt eye gt lt data options gt This specifies what types of data is present in event lines as a sequence of keywords The lt data type gt is one of GAZE HREF or PUPIL The eye
39. either the Display or Host PC to perform all keyboard shortcut operations while the eye image is displayed Poor Focus Good Focus Figure 3 7 Focusing the Desktop Mount Camera The camera should be focused by rotating the lens focusing ring Turn the lens by placing your thumb on the bottom of the lens and turning the focusing ring by sliding your index finger along the top of the camera This will prevent the camera image or the illumination to the eye from being blocked Look closely at the eye image on the zoomed view while adjusting the focusing ring until the eye image is clear If a turquoise or yellow circle CR signal appears near the pupil the best focus will minimize the size this colored circle By default the Illuminator Power level in the Camera Setup screen is set to T5 at the recommended distance If the Desktop Mount is placed too further An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd away from the observer or if you find the pupil is not reliably acquired you may consider increasing the illumination level to 100 Now proceed to section 3 3 Setting Pupil Threshold 3 2 4 EyeLink Remote Participant Setup The EyeLink Remote is designed for applications where a chin rest or head mount is not desirable or perhaps even possible i e patient work gerontology children etc The EyeLink Remote provides 500 Hz monocular tracking as well as 500 Hz head distance estimatio
40. left to right repeatedly The third block presents white dots at three locations along the horizontal axis The final fourth block presents a white dot a few seconds later another white dot is shown The original white dot then fades away An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd 4 Data Files The EDF file format is used by the EyeLink tracker and supporting applications to record eye movements and other data It is designed to be space efficient and flexible allowing for complete records of experimental sessions and data It adapts to monocular and binocular recording with backwards compatibility for future enhancements The EyeLink 1000 EDF file format is backwards compatible with the original EyeLink and EyeLink II EDF file format The EDF file format is a platform portable binary record of eye position and synchronization events This format is used directly for EyeLink Data Viewer application and may be translated by the EDF2ASC utility into a text format ASC file This file lists most of the important data in the EDF file in a more easily accessible format but at the expense of much larger file size Note By changing the File Sample Filter from Extra to Standard or Off this will affect EyeLink Data Viewer EDF2ASC and other analysis tool data calculations SR Research Ltd recommends leaving the File Sample Filter setting on the Set Options screen to Extra 4 1 File Conten
41. limit area is used to exclude regions of the camera image e g frame of the glasses eye brow that may otherwise be detected as a pupil CR reflection pattern If the search limit box isn t aligned on top of the pupil press A or the Align Eye Window button to center it The size and shape of the search limit area can be adjusted by pressing ALT and cursor keys on the host keyboard together ALT ff or U to adjust the height ALT lt and gt to adjust the width The position of the search limits can be adjusted with SHIFT and cursor keys 17 The operation of the EyeLink Remote is influenced by ambient lighting In general the pupil shrinks in a bright environment and dilates with dim lighting It s important that the user check the pupil size reported in the status panel in the Offline Calibrate Validate Drift Correct Output and Record screens seeFigure 3 11 If a yellow size warning is constantly observed it is likely that the pupil size is too small and as a An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd result the recorded data will be noisy If this happens first check whether the subject is seated at the recommended eye target distance of 950 600 mm Dimmer room lighting will also help avoid this warning PUPIL PUPIL OK or SIZ SIZE CORNEAL CORNEAL OK OK TARGET TARGET OK OK Pupil size looks OK Pupil size warning size too small Figure 3 11 Status Panel Pupil Siz
42. may be directly computed from the HREF x y pairs There are several methods of specifying eye rotation angles The angular distance eye rotation magnitude between any two HREF points is directly computable The C code to compute this angle is given below Remember to multiply the result by 57 296 to get the angle in degrees fo x xx y Xp 2 2 2 2 2 2 NIGI tX cy x f x y The HREF angular resolution may be computed as the first derivative of the rate of change of HREF position with angle It is sufficient to compute the resolution separately for the x and y coordinate directions This may be used to compute true eye movement velocities by dividing computed velocity in HREF units by the resolution for the sample These formulas give the x and y resolution in units of change in HREF position per degree of visual angle angle a cos 2 2 2 xres 0 01745 x Ca 2 2 2 yres 0 01745 x ier dea f TS x 4 4 2 3 GAZE Gaze position data reports the actual x y coordinates of the subject s gaze on the display compensating for distance from the display The units are in actual display coordinates usually pixels which can be set in the EyeLink 1000 configuration file PHYSICAL INI The default EyeLink coordinates are those of a 1024 by 768 VGA display with 0 O at the top left The resolution data for gaze position data changes constantly depending on subject head position and point of gaze and therefore is reported as a sep
43. most purposes the centroid algorithm is recommended as it has very low noise However if the pupil may be significantly occluded for example by the eyelids the ellipse fitting algorithm may give a more accurate estimation of pupil position The ellipse fitting mode decreases drift potential and copes well with pupil occlusion but at the cost of a higher noise level The EyeLink Remote exclusively uses the ellipse fitting pupil model An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd 3 7 Calibration The preceding steps set up the EyeLink 1000 camera system to track the positions of the pupil and CR of the selected eye Almost all eye movement research requires information on the subject s point of gaze on a display of visual information such as a screen of text To compute this we need to determine the correspondence between pupil position in the camera image and gaze position on the subject display We do this by performing a system calibration displaying several targets for the subject to fixate The pupil CR position for each target is recorded and the set of target and pupil CR positions is used to compute gaze positions during recording There are several possible calibration types available each of which serves different purpose By default a nine point calibration type HV9 is used This is good for most of the eye tracking applications However if a large calibration region is used the
44. mta y 25er ines onem masa Da eg auase a e PaR RUE dE 80 Old Experiment PrACliCe cuusesiospursopbaE sen ee teo reddi dac EEEa E 81 3 15 Next Steps Other Sample Experiments eere 82 4 Dala FIGS e 85 Al Pile Contents HR 85 4 2 Recording EDF Files a saxcessecortacuvesntieinstawadosaasewnddandsemaessew ag eE r ania 86 4 2 1 Recording from the EyeLink 1000 Host PC 0 ccccsseceeeeeeeneeeeeeeeeaneeeeeeeeaes 86 4 2 2 Recording from the EyeLink API or SR Research Experiment Builder 86 4 gt The EyeLink On Line Parser 05m eti eoUREDDRIdUNET HA EUN ea Seded E eai 86 4 8 1 Parser Operation eeiissssesiissssee sees es nnne nena nnns nna ann suas nasa asas saa and 86 LIP MEME Vicar 87 4 89 8 EyeLink Parser Configuration eeeesssseeeiise eese enne nana nnn nna 87 Ai 7107 39 70 m 88 4 3 5 Saccadic ThresholdS uostri te xai emque affa 88 496 UIS Woo 89 du JUXQUODUDUOl S eee ee ene ee eee MIR pU Dude 89 430 8 Other ParamelOrs esest entrato aate pex qo e dal EE e D Y EE E E E 90 40 9 Sample ConfiQUratloriS uea itt png a ena sumas cebat nasa ad eise tek vdasa ke kis 90 4 3 10 Heparsing EyeLink Data Files esses eese een nnn 91 eee Wale Wala Ty Cs EORR 92 AA o0 RC 92 LE E FOSON EDI CT n
45. of the FCC rules Operation is subject to the following two conditions 1 this device must not cause harmful interference and 2 this device must accept any interference received including interference that may cause undesired operation CISPR WARNING This is a Class A product In domestic environments this product may cause radio interference in which case the user may be required to take adequate measures WARNING Changes or modifications not expressly approved by SR Research Ltd could void the user s warranty and authority to operate the equipment This includes modification of cables removal of ferrite chokes on cables or opening cameras or connectors WARNING Opening or modifying cameras and connector will void the warranty and may affect safety compliance of the system No user serviceable parts inside contact SR Research for all repairs CONTACT ADDRESS SR Research Ltd 5516 Main St Osgoode Ontario Canada KOA 2WO Phone 613 826 2958 Fax 613 482 4866 Toll Free Phone 1 866 821 0731 North America Only Email support sr research com http www sr research com 2005 2009 SR Research Ltd Table of Contents 1 BUNCE LC CO mr cc aN 1 l l upporiuns DOCU NE a moet E aston ennesn cadence FMHMARI ONU 3 1 2 EyeLink 1000 System Configuration eesssesseessesseeee e nennen 4 D ME uo ee ee eee ee ee eer E eee ee 4 DDN ag nn een E ee eee es Meee eT ee er en ene 5 1
46. or R indicating the eye s data that produced the event The end of and summary data on the fixation is reported with the EFIX line This reports the time of the first and last sample in the fixation and computes the duration of the fixation in milliseconds The average X and Y eye position the type of position data is determined when the event was generated and the average pupil size area or diameter are reported Optionally the eye position angular resolution in units per visual degree is given as well All samples that are within the fixation will be listed between the SFIX and EFIX event for each eye simplifying data analysis 4 9 3 7 Saccades e SSACC eye lt stime gt e ESACC eye lt stime gt etime dur lt sxp gt lt syp gt exp lt eyp gt ampl pv Data Files 2005 2009 SR Research Ltd e ESACC eye lt stime gt etime dur lt sxp gt lt syp gt exp lt eyp gt ampl pv Xr yr The start of saccades are reported with a SSACC line which can be eliminated with the EDF2ASC nse option from the command line prompt or by enabling Block Start Event Output from the EDF2ASC converter GUI preference settings The eye is L or R indicating the eye s data that produced the event The end of and summary data on the saccade are reported with the ESACC line This reports the time of the first and last sample in the saccade and computes its duration in mill
47. pupil is clearly visible then the pupil size may be too small please check the camera distance and the illumination level Consider placing the Desktop Mount closer to the subject between 40 and 70 cm from the subject s eye and or increasing the illuminator power level 3 4 Setting the Corneal Reflection CR Threshold For typical experiments the Tracking mode should always be set to pupil CR mode regardless whether you plan to use head stabilization or not The pupil only mode should only be used together with a bite bar The corneal reflection if present is identified by a circular shape surrounded by a crosshair An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd Thresholds Thresholds Good Corneal Reflection Poor Corneal Reflection Figure 3 19 Corneal Reflection In the images depicted in this chapter the coloring is yellow though more recent versions of the Host PC software use turquoise coloring so there is a well defined boundary between the edge of the CR and the background CR threshold colouring is a configurable parameter of the Host application Follow the following steps to acquire the best CR a Press the Auto Threshold button to set the CR threshold You should see a colored circle appear near the pupil on each eye Auto Threshold should almost always set the correct CR threshold b If the auto thresholding sets the threshold too low or high use the CR threshold butt
48. recorded will be one word LEFT or RIGHT The data option keywords currently supported are o RES for resolution data both may be present o RATE for the sample rate 250 00 500 00 1000 0 or 2000 0 o TRACKING for the tracking mode P Pupil CR Corneal Reflection o FILTER for the filter level used O off 1 standard 2 extra e SAMPLES lt data type gt lt eye gt lt data options gt This specifies what types of data is present in sample lines as a sequence of keywords The lt data type gt is one of GAZE HREF or PUPIL The eye recorded will be LEFT or RIGHT The lt data option gt keywords currently supported are VEL for instantaneous velocity data RES for resolution data both may be present RATE for the sample rate 250 00 500 00 1000 0 or 2000 0 TRACKING for the tracking mode P Pupil CR Corneal Reflection o FILTER for the filter level used O off 1 standard 2 extra 4 10 Processing ASC Files O O O An ASC file is a simple text file and thus can be accessed by almost any programming language The usual way to process the file is to read each line into a text buffer at least 250 characters in size and to scan the line as a series of tokens non space character groups Data Files 2005 2009 SR Research Ltd The first token in each line identifies what the line is First character in first token Line type no token Blank li
49. select the tracked pupil using the mouse cursor and click the left mouse button If the camera image is not focused rotate the focusing arm and look closely at the eye image on the zoomed view The best focus will minimize the size of the corneal reflection circle usually colored turquoise or yellow An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd 10 If the pupil is detected a green box and crosshairs will now be drawn on the eye image in the global view In the zoomed view the pupil area is overlaid with a blue threshold overlay If the blue area in the display is interfering with setup press the Threshold Coloring button or T on the keyboard to remove the threshold overlay In TRACK EXE you can use keys on either the Display or Host PC to perform all keyboard shortcut operations while the eye image is displayed Pupil 38 AUTO x0 72 Pupil 82 AUTO x1 08 Pupil 111 AUTO x1 23 CR 209 AUTO x1 00 CR 203 AUTO x1 00 CR 06 AUTO x1 00 PUPIL OK PUPIL OK PUPIL OK CH OK CK OK CK OK Threshold bias too low Properly thresholded Threshold bias too high Figure 3 10 Pupil and CR Thresholds and Bias Values 11 A properly thresholded pupil should be solidly blue with minimal blue elsewhere in the image If the threshold is too low the blue area will be smaller than the pupil and the image will show excessive movement If the threshold is too high there will be shadows at the edges and corners o
50. several data field including e Time of the sample timestamp in milliseconds e eye position data in gaze HREF or RAW data monocular or binocular e Pupil size monocular or binocular e Button or input port state bits All samples contain a timestamp recorded in milliseconds The time is measured from the time when the tracker software was started This timestamp makes detection of missing samples possible as well as simplifying processing of data Usually all samples produced by the EyeLink 1000 tracker are recorded Other types of sample data are discussed in greater detail below 4 4 2 Position Data Data Files 2005 2009 SR Research Ltd Eye position data is produced by the EyeLink 1000 tracker every 0 5 1 20r 4 milliseconds depending on the tracking mode and speed set It is then processed to compute eye rotation angles and to compensate for subject head motions The processed data in one or all of these forms may be recorded in the samples Data is written as x y coordinate pairs or two pairs for binocular data The types of position data available are explained below 4 4 2 1 PUPIL Pupil position data is raw x y coordinate pairs from the camera It has not been converted to eye angles or to gaze position There may be a non linear relationship between this data and true gaze position Pupil position is reported in integer values with 200 to 400 units per visual degree When a calibration has not been performed
51. subjects where the ENTER key must be pressed to collect each fixation Pressing the M key switches automatic calibration off It may be switched back on by pressing the A key In addition the Backspace key may be used in the middle of a calibration sequencing to backtrack the calibration sequence With each press of this key the data collected for the last point in the calibration sequence is erased and new calibration data can then be collected This can be used to improve calibration accuracy for one or few selected points without having to restart the calibration procedure This is especially helpful for those subjects whose calibration data is hard to get When the last calibration target has been presented the calibration will be evaluated At the bottom of the Calibrate screen each eye s calibration is graded and displayed as follows GOOD green background No obvious problems found with the data FAILED red background Could not use data calibration must be repeated The background color of the message indicates the usability of the calibration We must still validate the accuracy of the calibration only serious problems can be detected here If problems are found examine the pattern formed by the pupil position cursors arrays of crosses for misplaced or missing fixations If the calibration was successful you may press the Accept button or the key to accept the calibration results Pressing the
52. the EyeLink system cannot convert pupil data to the more useful data types Raw pupil position is useful when auto sequencing calibrations or when the application wishes to perform its own calibration Most users will not need this data type 4 4 2 2 HREF The HREF head referenced position data directly measures eye rotation angles relative to the head It does not take into account changes in subject head position and angle or distance from the display However it may be more accurate for neuro psychophysical research as it reflects real eye movement velocities and amplitudes The x y coordinate pairs in HREF data reflect the line of sight in the geometric model below HREF Plane eye The x y positions define a point in a plane at distance f 15000 units from the eye The HREF units are independent of system setup display distance and display resolution The HREF coordinates are reported in integer values with 260 or more units per visual degree The 0 O point in the coordinate system is arbitrary as the relationship between display positions and HREF coordinates changes as the subject s head moves Even when a chinrest is used to stabilize the subject s head head rotations of several degrees can occur HREF coordinates are best used for determining angles relative to a known eye position or to measure eye movement velocities as described below Data Files 2005 2009 SR Research Ltd The eye rotation angles
53. 2 8 EyelLink 1000 Camera Mount Configurations essere 6 Lo y SPOTL SG CINCO ING serene a Rate REM IER Ed d UMEN MU EM MEME 9 1 8 1 Operational Functional Specifications osse eene 9 cr Ph ealo e CIM CANO ING uestem asioeres doc 3en tose ras aan E seeewageue casei sates 10 2 EyeLink 1000 Host Application eese esee 12 2 1 Starting the Host ADDIICATIOD uso ieezos tuve oi riant nuri N E Pa arx Eese 12 2 2 Modes PO DOE EI OB sora een nen EEE S A PNE OM MET EUM PROP 12 2 3 EyeLink 1000 Host PC Navigation eret itr rore hr Ix e EROR 13 2 3 1 Offline SCICCN 14 202 Cel O o EEE E E EE EE E E E A E oteinubdsge 15 209 CATET Aa I TOO eee E MER UU E 22 2 3 4 Calibrate SCKOCN ccccccsscccccsseecececseneeceeseeeeessaseseeesssueeeessaeesecssaaeecessaaeseessaqens 27 ZOD VNC QC O MNT R 30 2 3 6 Drift Check Drift Correct STON nrasane a 32 237 SU OSTOON ERE m EN 33 EG AOOO OC OC are E E E E AE EE RA E E EE 35 PA AS Ae EE EE N EEN A E I E ES aaa E E S 41 25 MOUE S MAON MOE eerror E T 42 2 6 Configuration Files and Experiment Directories sssssrreesssssssrrees 42 3 An EyeLink 1000 Tutorial Running an Experiment 45 3 amp 1 The Camera Setup SGCrECI iosovr EUR RERO NER DO UEM ERU a ORS 46 S MEE lante ANT SED RC 47 3 2 1 Tower Mount
54. C file produced by EDF2ASC that contains both samples and events the STARTFIX event will precede the first sample in the file that is part of the fixation and the ENDFIX event will follow the last sample in the fixation This allows the sample data in the files to be processed by saccade or fixation in a single pass The data contained in STARTFIX and ENDFIX events may be configured by modifying the DATA INI file for the EyeLink 1000 tracker For most research only simple fixation statistics are required such as average position and pupil Data Files 2005 2009 SR Research Ltd size STARTFIX events may also be configured to contain only the start time of the fixation Other data in the ENDFIX event may be useful for some types of analysis The resolution may be used to estimate angular distance between fixations Subtract the x and y position data for the fixations divide by the average corresponding resolution data and compute the Euclidean distance dx x1 x2 rx1 rx2 2 0 dy yl y2 ry1 ry2 2 0 dist sqrt dx dx dy dy 4 5 3 3 Fixation Updates Data within a fixation can be broken into smaller time segments useful for real time analysis and control via eye movements FIXUPDATE events may be produced at regular intervals within a fixation and contain data for a specified length of time within the fixation The data recorded in the FIXUPDATE event is similar to that in the ENDFIX event FI
55. EyeLink 1000 User Manual Tower Desktop LCD Arm Primate and Long Range Mounts Remote 2000 Hz and Fiber Optic Camera Upgrades Version 1 5 0 SR Research Xen Pett EyeLin Copyright 2005 2009 SR Research Ltd EyeLink is a registered trademark of SR Research Ltd Mississauga Ontario Canada Read instructions before use Entela Safety Mark Compliance of this product with UL 60950 3 4 Edition CSA C22 2 No US 60950 00 CAN CSA is certified by Entela an independent testing body C Certified CLASS 1 LED DEVICE IEC 60825 1 Ed 1 2 2001 CAUTION Use of controls or adjustments or performance of procedures other than those specified herein may result in hazardous radiation exposure FCC Statement NOTE This equipment has been tested and found to comply with the limits for a Class A digital device pursuant to part 15 of the FCC Rules These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual may cause harmful interference to radio communications Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at the users expense FCC Notice This device complies with Part 15
56. FAULTS INI file of the EyeLink 1000 tracker or may be sent over the link recording parse type data type one of PUPIL HREF or GAZE gt The data type used for parsing will always be included in the event data Other data reported for eye movement events are controlled with the file event data command This is followed by a list of data types and options selected from the list below Keyword Effect GAZE includes display gaze position data GAZERES includes units per degree screen resolution for start end of event HREF includes head referenced eye position AREA includes pupil area or diameter VELOCITY includes velocity of parsed position type average peak start and end STATUS includes warning and error flags aggregated across event not yet supported FIXAVG include ONLY averages in fixation end events to reduce file size NOSTART start events have no data other than timestamp The file event data command may be edited in the DATA INI file of the EyeLink 1000 tracker or may be sent over the link Some example settings are given below GAZE GAZERES AREA HREF VELOCITY default all useful data GAZE GAZERES AREA FIXAVG NOSTART reduced data for fixations GAZE AREA FIXAVG NOSTART minimal data 4 6 3 Event Types The file event filter command specified what type of events will be written to the EDF file It may be changed in the DATA INI file of the EyeLink 1000 tracker or may be sent over the link The co
57. Participant Setup Monocular essere 48 3 2 2 Using the LCD Arm Mount Positioning the Apparatus 50 3 2 8 Desktop Mount Participant Setup Monocular seeeussess 52 3 2 4 EyelLink Remote Participant Setup eei sees 55 3 2 5 Primate Mount Participant Setup Monocular sees 62 2005 2009 SR Research Ltd EN 3 2 6 Desktop Mount Participant Setup Binocular eeeeeeessssus 62 3 2 7 Long Range Mount Participant Setup Monocular or Binocular 65 9 9 Serie Pupil Threshold 2p 4 ccenccaer ooh erre dup ureRbonoPIuPIF ETES 68 3 4 Setting the Corneal Reflection CR Threshold eceeeesess 69 Ch i 0 rem 71 0 0 Pupil Tracking Algorit sce accscccaseevaccalnccasecncunwtrcecaeresesouacaeetecoantecseneees 71 Cy Ge CAD Oea ee tr ret eter th tamer nr neste etre reer eet tere tare 72 ee lio ire RTT steee eae bac ease raemtangeessontianenseseieennates 19 3 9 Improving Calibration Quality ssereseesesessssssssssssssssosereeeeeeesesessssso TT 3 10 Recording Gaze Position sesseseeerereeeeseressssssssesssssosrorereeeeeeeeeseso 78 3 11 Drift Correction Drift Checking ccc ccc cece eee ee eee eeeeeeeeeenes 79 3 12 Exiting the Host Application e maie puencvaddeiltadea rode hens nbn ce Dua cents testas 80 Sako EyeLink 1000 Setup SU
58. Restart button or the ESC key will restart the calibration Pressing ESC twice exits to the Camera Setup screen Some users especially the programmers in the phase of testing experiment programs may want to run calibration and validation with mouse simulation To do this first delete all of the M cal files in the C ELCL EXE directory of the Host PC Start the EyeLink program set the Tracking option as Mouse An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd simulation Go to the Camera Setup screen type C This will bring up the Calibrate screen Press the space bar only once to initiate the calibration process One cross will be immediately printed on the screen In addition the calibration target and the mouse cursor move to a second calibration point Press the left mouse button on the Host PC Click the left mouse cursor for all of the following calibration targets until the calibration finishes The Status Panel reports the current status for pupil corneal reflection and target EyeLink Remote only signals and thus will indicate any lapses in collecting data In normal operation the indicators are green Should any of the indicators display a color other than green there is a problem with the setup that must be addressed to prevent data loss Indicates Status of CR Pupil OK Pupil is visible SIZE Pupil is too large MISSING Pupil is missing The pupil status
59. The threshold should be set to zero for non cognitive research or where statistics such as saccadic duration amplitude and average velocity are required Examples of the commands to set these thresholds are saccade velocity threshold 30 saccade acceleration threshold 8000 saccade motion threshold 0 15 4 3 6 Pursuit Thresholds During smooth pursuit and nystagmus saccades must be detected against a background of smooth eye motion as fast as 70 sec While acceleration can be used to detect these saccades velocity data must also be used for reliable detection of all saccades The EyeLink 1000 parser raises the saccadic velocity threshold during pursuit by the average velocity over the last 40 milliseconds This is reliable and does not degrade parser performance during non pursuit eye movements During long saccades such as the return sweep in reading this fix up causes the saccadic velocity threshold to be raised This is not a problem as long as the adjustment is limited as it helps to prevent prolongation of these saccades by overshoots and glissades The pursuit threshold limits the amount that the saccadic threshold can be raised A limit of 60 sec works well for most pursuit and other research but may have to be raised if very rapid pursuit or nystagmus is being recorded The limit is set in degrees per second An example of this command is saccade pursuit fixup 60 4 3 7 Fixation Updates Monitoring eye position
60. Timor OW a eur ie Ps RIS OR I Ir eui QIN EE M MET 115 6 2 1 Non Serviceable Components eise sees 115 6 2 2 llluminator REPLACEMENT cccccccscccsssecnsusensuecccuscccuecnsusensusensusceaeessnsnsens 115 T ICMEEC I IURI 116 6 2 4 Power Supply Replacement cccccccsssececccsseeeececsueeeeesseeeecesaseeeesssaeseessanens 116 6 9 Limited Hardware Warranty eiio oio tee suo innie ia en EEEN e niu HEU NU EEE 117 6 4 Limited Software Warranty doeet eee eoe eden ok eye uxon a ERPRE LORS RUN 118 OGS COopyriehts 7 Trademarks ucosntusbUn E RUNE UU hod Rusa PIED IE KRMEDEU NAE 118 T Appendix A Using the EyeLink 1000 Analog and Digital Output Card 119 7 41 Analog Data Eyp6es seussdqeenieens aetas dus eu i dieaseto dt odumastr ee ida dumb iania 119 2005 2009 SR Research Ltd BN E E oio aP ucECU NTT 120 7 3 Setting up the EyeLink 1000 Analog Card eeeeeeeeeeee 120 7 3 1 Installing Analog Output Hardware essen 120 7 3 2 Connections to Analog Card isses essen rennen nani 121 fao NoBbeand FILONO mE 121 7 4 Digital Inputs and Outputs ssssssssssssssssssssssssssseseereeeeeeesessseseeseso 121 74 1 Analog Data Output Assignments esses esee 122 7 4 2 Analog Data Types and RHanges esses eene 123 7 4 3 Scaling of Analog Position Data
61. Tower Mount Desktop Mount Camera Level Desktop Mount Camera Angled Primate Mount LCD Arm Mount and Long Range Mount Using these hardware configurations there are several different software modes Monocular recording can be achieved with each hardware configuration binocular recording is available when the camera is angled Desktop Primate and Long Range Mounts and the EyeLink Remote mode allows monocular recording without head stabilization Desktop and LCD Arm Mounts Depending on the license of your system and the requirements of your application you will need to choose one of the above recording modes Please continue with one of the following participant setup tutorials Highly Accurate Wide Field of View Monocular Recording 3 2 1 Tower Mount Participant Setup Monocular Using the LCD Arm Mount Positioning the Apparatus 3 2 2 Using the LCD Arm Mount Participant Setup Highly Accurate Head Stabilized Monocular Recording 3 2 3 Desktop Mount Participant Setup Monocular Accurate Monocular Recording Without Head Stabilization 3 2 4 EyeLink Remote Participant Setup Highly Accurate Wide Field of View Monocular Recording with Primates 3 2 5 Primate Mount Setup Monocular Highly Accurate Head Stabilized Monocular or Binocular Recording 3 2 6 Desktop Mount Participant Setup Binocular 3 2 7 Long Range Mount Participant Setup Monocular or Binocular An EyeLink 1000 Tutorial Running an Experiment
62. XUPDATE events are most useful in real time applications using the link Recording samples in the EDF file is more useful for most psychophysical research 4 5 3 4 Saccades The EyeLink 1000 tracker s parser detects saccades by the velocity and acceleration of the eye movements Because of variations in acceleration profiles the onset and offset point of saccades can vary by one or two samples from ideal segmentation done by hand Nonetheless the saccadic data compiled by the parser is sufficient for most neuro psychophysical research including smooth pursuit Most cognitive research will ignore the saccadic data using the fixation data produced by the EyeLink 1000 parser The saccadic data produced for saccades includes e The time of the first and last sample in the saccade The eye that generated the event Start and end HREF or gaze position data Peak eye movement velocity Start and end gaze data angle Gaze data angular resolution All of these data may appear in the ENDSACC event that terminates the fixation Only the starting data can appear in the STARTSACC event that initiates the saccade In a sorted EDF file or a text ASC file produced by EDF2ASC that contains both samples and events the STARTSACC event will precede the first sample in the file that is part of the saccade and the ENDSACC event will follow the last Data Files 2005 2009 SR Research Ltd sample in the saccade This allows the sample data in the files to
63. a for the tracked eye and optionally by X and Y velocity pairs for the eye and resolution X and Y values Missing data values are represented by a dot or the text specified by the miss option to EDF2ASC SAMPLE LINE FORMATS Data Files 2005 2009 SR Research Ltd e Monocular time xp lt yp gt ps e Monocular with velocity lt time gt xp lt yp gt ps xv lt yv gt e Monocular with resolution time xp lt yp gt ps xr lt yr gt e Monocular with velocity and resolution time xp yp ps XV yv Xr yr e Binocular lt time gt lt xpl gt lt ypl gt lt psl gt lt xpr gt lt ypr gt lt psr gt e Binocular with velocity time lt xpl gt lt ypl gt lt psl gt lt xpr gt lt ypr gt lt psr gt lt xvl gt lt yvl gt lt xvr gt lt yvr gt e Binocular with and resolution lt time gt lt xpl gt lt ypl gt lt psl gt lt xpr gt lt ypr gt lt psr gt lt xr gt lt yr gt e Binocular with velocity and resolution time xpl lt ypl gt psl xpr ypr lt psr gt xvl lt yvl gt lt xvr gt yvr xr yr DATA NOTATIONS ps monocular pupil size area or diameter left pupil size area or diameter t pupil eis le right pupil size area or diameter instantaneous velocity degrees sec degrees sec right eye instantaneous velocity degrees sec XXI lt yr gt X and Y resolution posi
64. ace at a time The gain and offset adjustments can be done either from the ff and U buttons in the Gain and Offset sections or by dragging the mouse cursor on the plot graph The current gain offset settings can be saved into a file pre and reloaded later For all eye data types the user can click on the Undo button to undo the last adjustment and on the Default button to load the default configuration settings S55 Sets the amount from 2 seconds to 60 seconds per sweep of data to be plotted on each screen Keyboard Shortcuts and gt change plot speed Toggles screen plotting although the recording continues Keyboard Shortcuts P Pause data plotting Marks the time pressed on the screen with a thin white line Keyboard Shortcuts INS add rewind marker EyeLink 1000 Host Application 2005 2009 SR Research Ltd Clears data since last marked point If no marker is set clears from the left end of the screen Keyboard Shortcuts DEL rewind to marker or start Clears data in the plot view Keyboard Shortcuts HOME Clear all data a urs MJ selects which eye traces to be displayed VIS or JUTST ADJ adjusted ADJ At least one of the eye traces must be UTS ADJ JUTS ADS visible Keyboard Shortcuts X or Y Data trace to select or view Selects zooming level or use ALT and ALT keys These buttons will only be available when the plotting data type i
65. al per unit resolution of 5 um 0 005 mm Pupil size measurements are affected by eye position due to the optics of the eye and camera Position data output can be selected from one of three types of measurement Raw This measurement is the raw pupil center position or pupil minus corneal if running in pupil CR mode as measured by the image processing system This measurement is available without performing an eye tracking calibration HREF This measurement is related to the tangent of the rotation angle of the eye relative to the head In the default EyeLink 1000 setup and for the 5V to 5V output range it is oV tan angle measured separately for vertical and horizontal rotations A calibration must be performed to properly obtain this measure Appendix A Using the EyeLink 1000 Analog and Digital Output Card 2005 2009 SR Research Ltd Gaze This is actual gaze position on the display screen A calibration must be performed to obtain this measure The EyeLink 1000 system offers integrated data recording and digital data transfer methods which do not suffer from the timebase resolution and noise degradation inherent in analog systems 7 2 Analog Data Quality The EyeLink 1000 analog output system is intended for use with commercial data collection systems such as LabView or for backwards compatibility with existing eye tracking software and systems However analog data transfer may significantly degrade data quality
66. amples but will still result in steps in the data Recording the digital strobe output on an analog or digital input channel in combination with the analog data allows the first data from each sample to be selected by detecting the change in value of this output By setting the duration of the strobe pulse to O the strobe output can be set to toggle between high 4 to 5 volts and low 0 to volt for every sample which produces the best signal Over sampling can also be used without the strobe when the analog data is being used to drive a gaze contingent display as the time of each sample is unimportant and over sampling will minimizes total data delay Appendix A Using the EyeLink 1000 Analog and Digital Output Card 2005 2009 SR Research Ltd
67. and data messages from applications These can Data Files 2005 2009 SR Research Ltd be used to record the time of a change in the display or an experimental condition 4 2 Recording EDF Files EDF files are created by the EyeLink 1000 tracker recording eye position data events from the on line parser and button and input events These are recorded only when the tracker is in output recording mode Messages sent from applications on the Display PC through the Ethernet link may be recorded at any time Recording EDF files involves opening a data file recording data from one or more sessions in output mode and closing the file These operations can be performed manually using the EyeLink 1000 Host application on the Host PC or remotely from the Display PC through the Ethernet 4 2 1 Recording from the EyeLink 1000 Host PC In some eye tracking situations it is most convenient to initiate the recording of eye movement data directly For example displays may be generated by manually operated equipment or by non EyeLink applications Special provisions must be made for display of the calibration pattern By using the EyeLink 1000 tracker s Output Screen files may be opened and closed and recording sessions may be started and stopped Refer to Chapter 2 of this manual EyeLink 1000 Host Application Operation for information 4 2 2 Recording from the EyeLink API or SR Research Experiment Builder Most eye movement research invol
68. andalone system These output modes are not mutually exclusive and include a Analog Output Using the optional analog output card data are available in analog format Analog output options are configurable via the Set Options screen and in the ANALOG INI initialization file b File Output Eye data are available in the EyeLink EDF file format see Chapter 4 Data File This can be converted to an ACSII file using the EDF2ASC conversion utility or analyzed with EyeLink Data Viewer File output options are configurable via the Set Options screen 2 3 EyeLink 1000 Host PC Navigation The EyeLink 1000 tracker interface consists of a set of setup and monitoring screens which may be navigated by means of the Host PC mouse key shortcuts or from the Display PC application via link commands Each of the modes shown in Figure 2 2 has a special purpose Where possible each screen has a distinctive appearance Screens with gray bars contain menus of key options for navigation and setup Other screens have a key navigation bar at the top of the screen and a status bar at the bottom Arrows represent the navigations possible by key presses on the Host PC keyboard or via button selection using the Host PC mouse All modes are accessible from the Display PC by link control Note the central role of the Camera Setup menu it serves as the mode control during subject setup The functions of each mode and the main access keys to other modes are
69. ar considerations Once the Arm is in position steps to take to collect good data are identical to those of the other mounts An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd To position the Arm simply grab the entire apparatus by one or both of the handles located on either side of the LCD display and pull it into position Note that the Arm can swing completely around move up and down and bend at every joint Furthermore the LCD display can be tilted forward or backward and rotates around the swivel joint that attaches it to the Arm Ideal positioning of the LCD Arm Mount places the LCD display e perpendicular to the viewer s line of sight e with their gaze centered and e intersecting with the top of the display If the viewer is sitting upright in a chair this means than the monitor should form a right angle to the floor and that their gaze should strike the monitor in the middle and in the top 25 of the display area If the observer is reclining then place the monitor surface so that it is perpendicular to and in front of their face A final important consideration particularly for monocular viewing with head stabilization is the distance between the LCD display and the observer The PHYSICAL INI file see the Installation Guide specifies the viewing distance between the observer and the monitor as well as the monitor dimensions For the EyeLink Remote viewing distance is computed dynamically
70. ar or ENTER key on Host or Display PC in order to gather the sample when the subject is looking at each calibration or validation target If disabled the calibration and validation procedure automatically samples once the eye settles Keyboard Shortcuts Y toggle Force Manual Accept on off Camera Position Detect Clicking the Camera Position Detect button polls the position of the camera selection knob to determine the eye to track This option is only available for the Tower Mount Keyboard Shortcuts K toggle camera eye autodetect on or off Lock Tracked Eye Lock the setting of the eye to record eye on the Display PC keyboard if performing a monocular recording This option is applicable to binocular data collection modes only Keyboard Shortcuts K Lock the currently selected Eye Search Limits though not recommended for most subjects are useful for images with pupil or CR foils such as reflections off of glasses or makeup Search Limits delimit the area of the camera image indicated by a red boundary in the Host PC global view to be examined for the pupil or CR A red boundary around the searched area appears in the Host PC s global view Tracking If Search Limits is selected Search Limits Move Limits and the pupil position is i i moved search for the pupil is confined to the bounded area otherwise the whole image is searched for the pupil If Move Limits is checked the limited sea
71. arate data type see below A typical resolution is about 36 pixels per degree for the suggested EyeLink 1000 setup with the distance between the subject s eyes and the display being twice the display s width and with a default 1024 by 768 screen resolution The high resolution of the EyeLink 1000 data is preserved by multiplying the position by a prescaler recording the value as an integer in the EDF file then dividing by the prescaler when the file is read The usual prescaler value is 10 allowing gaze position to be recorded with O 1 pixel of resolution Actual EyeLink 1000 resolution is limited only by measurement noise 4 4 2 4 Gaze Resolution Data Data Files 2005 2009 SR Research Ltd For gaze position unlike the HREF data the relationship between visual angle and gaze position is not constant The EyeLink 1000 tracker computes and can record the instantaneous angular resolution at the current point of gaze This is measured as the units usually pixels per degree of visual angle computed for a change in x and y position separately This resolution data may be used to estimate distances between gaze positions and to compute velocities of eye movements To compute the angular distance of two points compute the x and y angular distances of the points separately by dividing the distance in pixels by the average of the resolutions at the two points then compute the Euclidean distance from the x and y distances For instantane
72. at operation of the software will be uninterrupted or error free You assume responsibility for selecting the software to achieve your intended results and for the use and results obtained from the software SR Research will fix reported software error in a best effort fashion and can not provide a guarantee of solution availability time THIS EXPRESS LIMITED WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES EXPRESS OR IMPLIED INCLUDING ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE IN NO EVENT WILL SR RESEARCH LTD BE LIABLE FOR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES Some jurisdictions do not allow limited on the duration of an implied warranty so this limitation may not apply to you In no event shall SR Research Ltd or its suppliers be liable for any damages whatsoever including without limitation damages for loss of business profits business interruption loss of business information or other pecuniary loss arising out of use or inability to use the software even if advised of the possibility of such damages Because some jurisdictions do not allow an exclusion or limitation of liability for consequential or incidental damages the above limitation may not apply to you 6 5 Copyrights Trademarks EyeLink is a registered trademark of SR Research Ltd All other company and or product names are trademarks of their respective manufacturers Product design and specifications may change at
73. ation sequence according to Auto Trigger the Pacing Interval from the Set Options screen Keyboard Shortcuts A Auto Trigger Accept Press to accept fixation value after the participant s gaze is stable on the target Keyboard Shortcuts ENTER Spacebar Accept Fixation 2 3 5 3 Validate Screen Key Shortcuts Key Fumetion O A Auto calibration set to the pacing selected in Set Options EE menu Auto trigger ON EyeLink accepts current fixation if it is stable During Validation O V O First Point Exit to Camera Setup Following Points Restart Calibration ENTER or Spacebar Begins calibration sequence or accepts calibration value given After first point also selects manual calibration mode Manual validation Auto trigger turned off A Auto validation set to the pacing selected in Set Options menu Auto trigger ON EyeLink accepts current fixation if it is stable Repeats previous calibration target After Validation Help screen Accept validation values Discard validation values EyeLink 1000 Host Application 2005 2009 SR Research Ltd 2 3 6 Drift Check Drift Correct Screen Drift Check TCF IF Link Open Tracking Hight Eye Pupil CH i 1 Checking Target Fisatiar Figure 2 8 Drift Check Drift Correct Screen 2 3 6 1 Drift Check Drift Correct Screen Purpose The Drift Check Drift Correct screen displays a single target to the parti
74. basic EyeLink sample experiment The program performs the following steps i Initialize the EyeLink library and connect to the EyeLink tracker ii Create a full screen window and send a series of commands to the tracker to configure its display resolution eye movement parsing thresholds and data types iii Using a dialog box built into the EyeLink programming library ask for a file name for an EDF data file which it commands the EyeLink tracker to open on the Host PC hard disk iv Runa block of trials Each block begins by calling up the tracker s Setup menu screen from which the experimenter can perform camera setup calibration and validation Four trials are run each of which displays a single word v After all blocks of trials are completed the EDF file is closed and transferred via the link from the EyeLink hard disk to the Display PC vi At the end of the experiment the window is closed and the EyeLink library is closed An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd Each trial begins by performing an optional drift correction where the subject fixates a target to allow the eye tracker to correct for any drift errors Press the space bar to perform the drift correction Recording is then started Recording can be stopped by pressing the Esc key on the Display PC keyboard the EyeLink Abort menu Ctrl Alt A on the Host keyboard or by pressing any button on
75. be processed by saccade or fixation in a single pass The data contained in STARTSACC and ENDSACC events may be configured by modifying the DATA INI file for the EyeLink tracker Saccadic events may be eliminated entirely if only fixation data is required STARTSACC events may also be configured to contain only the start time of the saccade The peak and average velocity data for saccades is especially valuable for neuro psychophysical work These are the absolute velocities measured as the Euclidean sum of x and y components The EyeLink 1000 parser computes velocity by use of a 9 sample moving filter This is optimal for detection of small saccades minimizes extension of saccade durations and preserves saccadic peak velocities Other data in the ENDSACC event may be useful for some types of analysis The start and end position and start and end resolution may be used to compute saccadic amplitude This is more easily done by multiplying average velocity by the saccadic duration dist 1000 0 end time start time 1 0 avg velocity In general the saccadic amplitude will be slightly less than the distance between average position of the preceding and following fixations as saccades do not include sub threshold velocity parts of the eye movement that precede and follow the rapid phase 4 5 3 5 Blinks The STARTBLINK and ENDBLINK events bracket parts of the eye position data where the pupil size is very small or the pupil in t
76. brations per subject before beginning to collect data e Encourage subjects to sit still A subject that doesn t sit still probably is not paying proper attention to the experimental task e When writing your own applications try to match the background color of the screen during calibration and validation to that of the test displays An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd Changes in pupil size caused by large brightness differences can degrade the system accuracy e Always check for the pattern of the calibration grid For a 9 point calibration the fixation crosses should form three parallel horizontal or close to horizontal lines and three parallel vertical or close to vertical lines Redo calibration or camera setup if you are not seeing this 3 10 Recording Gaze Position After the system is set up and calibrated we can monitor gaze position in real time and record it for later analysis or viewing Pressing the Output button or the O key from the Camera Setup screen will display the Output menu where EyeLink Data Files EDF can be opened and closed and analog output if installed can be controlled TRACK EXE automatically opens a data file DATA EDF but you can change this by opening a new file in this menu Pressing ENTER or O again will enter Output mode and start display of gaze position and data recording In this session we assume the TRACK appli
77. camera licensing Values in Table are Color Coded EyeLink 1000 system EyeLink 2000 system required 3 Time from physical event until first registered sample is available via Ethernet or Analog output Optional data filter algorithm adds one sample delay for each filtering level EDF File and Link Data Types Measured with an artificial pupil 5 Pupil Only tracking mode is available for use in head fixed conditions 6 Binocular tracking with Desktop Mount can reduce allowed head movement to approx 25 mm Horizontal and Vertical Introduction 2005 2009 SR Research Ltd 1 4 Physical Specifications EyeLink 1000 Card Half length PCI 140 mm long by 100 mm high CLASS 1 LED PRODUCT IEC 60825 1 Ed 1 2 2001 Wavelength 910 nm Tower and Primate Mounts 890 nm Desktop Long Range LCD Arm Mounts Tower Primate Mount Eye illumination level less than 1 Eye Illumination mW cn at gt 200mm from illuminator Desktop LCD Arm Mount Eye illumination level less than 1 mW cm2 at gt 300mm from illuminator Long Range Mount Eye illumination level less than 1 mW cn at distances indicated on illuminator distance scale Windows 2000 XP Display PC Operating system API Mac OSX Linux Supports cables up to 10 meters in length Camera Data Cable Conforms to v1 0 and v1 1 of the CameraLink specifications 10 C to 30 C 1096 8096 humidity non condensing Operating conditions For indoor use only 10 C to 60
78. cated just to the left and to the right of the global camera image are available for use with Long Range and Primate Mount configurations The left one is used to rotate the camera image 90 and the right one is used to flip the camera image vertically Shows the tracked eye image Pupil and CR thresholds and status are indicated beneath the camera image In EyeLink Remote mode bias values for pupil and CR thresholds are displayed o Shows the camera target distance in millimeters and target threshold a Value EyeLink Remote only Illuminator Power Power level of the illuminators for the Desktop 25 Level and Angled and EyeLink Remote modes 75 100 Keyboard Shortcuts I change illuminator power level Tower Mount Camera Position Left Right Camera Position Detect Desktop Mount Angled Eyes to Track Left Lock Tracked Eue Desktop and LCD Arm Mounts Level Remote Level Eye Tracked Left Select the eye to track during recording Here the Left eye is selected Tower Mount Clicking Camera Position Detect polls the position of the camera selection knob indicating which eye is selected for tracking Desktop Mount Angled The Lock Tracked Eye button disables the ability to switch the eye being tracked from the Display PC as will pressing K Keyboard Shortcuts B track both eyes R track Right eye L track Left eye K autodetect camera position Tower Mount
79. cation is running on the Display PC When TRACK senses that the Host PC has entered Output mode it sets up a recording session under its own control On the Display PC it displays a page of text or a target grid on its own screen for the subject to read alternating between recording sessions The Host PC screen will show the pattern of boxes that corresponds to each letter or word on the subject s display This serves as a reference for the gaze position cursor displayed by the EyeLink 1000 during recording allowing the operator to see where the subject is looking and detect problems with eye tracking errors or of subject s inattention Applications can create similar feedback displays by sending the display screen image to the tracker PC before recording begins TRACK displays the gaze position as a red cursor on the subject display The cursor can be toggled on and off by the G key on the Display PC keyboard To implement this feedback TRACK requests that EyeLink send it 250 500 1000 or 2000 samples per second of gaze position via the EyeLink Windows DLL This data is used to move the gaze cursor TRACK also sends commands to the Host PC to create a data file DATA EDF on the Host PC s hard disk which contains samples fixations and saccade data When the TRACK exits this file will be automatically transferred from the Host PC to the Display PC DATA EDF may be viewed with EyeLink Data Viewer or An EyeLink 1000 Tutorial Running
80. ccessible from almost any programming language The converted ASC files contain lines of text with each line containing data for a single sample event or data parameter The EDF2ASC utility reads one or more EDF files creating text files with the same name but with the ASC extension It scans the input file reordering data as required and converting samples and events into lines of text It can also compute resolutions and instantaneous velocity for sample data The ASC file is about twice as large as the original EDF files EDF2ASC converter utility can be run from the GUI interface from your computer desktop click Start gt Programs gt SR Research gt EyeLink gt Utilities gt Visual EDF2ASC assuming that you have installed the EyeLink Data Viewer software The user can also run the EDF2ASC converter from the DOS command line prompt assuming that Windows Display Software has been installed To translate an EDF file from the command line prompt type edf2asc followed by the name of the file to be translated and any conversion options Wildcards and may be used in the input file name allowing conversion of multiple EDF files to ASC files with the same name Optionally a second file name can be specified for the output ASC file Many options exist for Data Files 2005 2009 SR Research Ltd the file conversion One set of options will be best for your work and creation of a single line batch file called for e
81. cific configuration files setup for Ethernet link driver data TCP IP address EyeLink 1000 Host Application 2005 2009 SR Research Ltd KEYS INI LASTRUN INI PARSER INI REMPARSE INI PHYSICAL INI PREINIT INI USB INI VIDOVL INI FINAL INI special key function definitions default user menus thresholds menu choices etc from the last session on line parser data types configuration saccadic detection thresholds for the Remote REMPARSER INI and non Remote modes PARSER INI SR RESEARCH DOES NOT SUGGEST MODIFYING THESE FILES monitor and display resolution settings all physical setup and simulation settings pre hardware initialization configuration file USB controller configuration file commands used to control the video overlay commands to be executed last may override or change the state of other settings Table 2 EyeLink 1000 Configuration Files If you plan to change the default settings in the INI files please copy and paste the target commands to the FINAL INI and make the modification in that file for the ease of future maintenance EyeLink 1000 Host Application 2005 2009 SR Research Ltd 3 An EyeLink 1000 Tutorial Running an Experiment The following tutorial will demonstrate and test the EyeLink 1000 system assuming that you have already arranged a proper layout of the EyeLink 1000 equipment and configured PHYSICAL INI for your setup see Section 1 1 Suggested Equip
82. cipant and then measures the difference between the computed fixation position and the current target For the EyeLink 1000 the default configuration leaves the calibration model unmodified The purpose therefore is to check whether the model has become grossly invalidated If the error is large the experimenter is prompted to acquire another sample If the error remains large i e the prior sampling error was reproduced the drift check will fail and another calibration will be required see Section 3 11 for more details To perform a drift check have the subject look at the first fixation point and click the Accept Fixation button or press ENTER or the Spacebar to evaluate the adequacy of the calibration parameters Important In EyeLink I and II systems the fixation error calculated during drift correction was used to shift the calibration map This linear adjustment often greatly improved the overall accuracy for upcoming recording However with the EyeLink 1000 we have found that correcting the calibration map based on the drift correction result has no significant effect and can actually reduce fixation accuracy during recording The default drift correction behavior of the EyeLink 1000 system in pupil CR mode is to report the calculated fixation error without altering the calibration map in any way Therefore the procedure is better viewed as a Drift Checking procedure in the EyeLink 1000 though a true Drift Correction can b
83. cking Hight Eye lHHH He Plupil CH TRACKED CH fey T Data to Fille SDEMO EDF RTT PIED e J INT METTI e and oL M InivGE HOT 1 PAR ILABLE ba Bia toy tpt Lap ties n Title THIAnL HECORDIMG TEXT Figure 2 10 Record Screen Gaze Cursor View The Gaze Cursor View plots the current gaze position of the subject in calibrated screen pixel coordinates Any graphics drawn on the idle mode screen are re displayed on the screen to be used as a reference for the real time gaze position cursor The gaze cursor view is only useful when the EyeLink system s built in calibration routines have been used for gaze position calculation The Plot View displays the x y data traces as a function of time The type of data to be plotted can be configured at the Set Options screen Since raw data can also be displayed in the plot view this view is useful in any data output mode even when calibration has not been performed EyeLink 1000 Host Application 2005 2009 SR Research Ltd pr fefauit Fit alt Tracking Right Eur NETT He Pupil CH Data to Fille SDEHO EBI Mnp les and Events k d Eumenis Lin Samples ard Ewer Ana hay Output amples Title THINL HECOHDIMG TEXT Figure 2 11 Record Screen Plot View 2 3 8 2 Record Screen Main Functions Gaze View and Plot View Stop Stops the recording of data to the EDF file Keyboard Shortcuts ESC Stop Recording Abort Trial Abort the trial recording
84. compatible with some glasses depending on the shape of the glasses and reflectiveness of the glasses and therefore you may not be able to track the subject even after adjusting the mirror angle the EyeLink 1000 Desktop Mount has a better compatibility with glasses Once the mirror angle is set to the intended position ask the subject to lean the forehead against the forehead rest on the Tower Adjust the height of the chair so that the subject is comfortable and his her eye line is aligned to upper part of the monitor The position of the forehead rest should be just above the eye brow The leftmost panel of Figure 3 3 shows a good chair height The rightmost panels show the subject seated too high or too low Good Chair Height Chair too High Figure 3 3 Adjust the Chair Height for EyeLink 1000 Tower Mount The experimenter should also ensure the subject s head position is vertical by adjusting the position of the chair so that the subject is seated either closer to or furtherer away from the table If the chinrest is used for the experiment adjust the height of the chinrest pad so that the subject s head is comfortably supported The user may also adjust the protrusion of the chinrest pad so that An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd it is furtherer away or closer to the subject by turning the knob underneath the chinrest In the global view window of the camera image now move the Host PC
85. configurations of the Host software simultaneously For instance you may move the eye tracker between several locations and have unique settings for each locale This can be easily done by duplicating the C ELCL EXE directory renaming it to something meaningful regarding your location e g C PSYCHLAB EXE and configuring the INI files within the directory for your location e g PHYSICAL INI By running the executable program from within this directory you will be able to use the specific settings for that particular locale For example while you may have one configuration set in the PSYCHLAB EXE directory you may have another in the MEGLAB EXE directory To collect data you would change to the relevant directory e g CD PSYCHLAB EXE or CD MEGLAB EXE and then run the executable program ELCL EXE EyeLink 1000 Host Application 2005 2009 SR Research Ltd For a given configuration it is recommended that you copy any commands or parameters you wish to modify into the FINAL INI file which will be the last configuration file to be processed by the tracker and thus override the settings listed in other INI files This design makes it easy to edit a single file to keep track of changes made makes updating the software easy just retain the settings in the FINAL INI and assists in troubleshooting The EDF files for an experiment are written to a disk partition and directory based on the parameters set in the
86. ctly and carefully validated The EyeLink tracker has a built in trial abort menu which may be used in experiments to terminate trials where setup problems are seen The Setup menu may then be used to fix eye setup or calibration and the interrupted trial may be restarted or skipped This sequence requires co operation from the experiment application and example code is provided in the developer s kit An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd 3 15 Next Steps Other Sample Experiments There are several sample experiments that are valuable demonstrations of how the EyeLink 1000 system can be used and programmed This section describes each sample experiments purpose and use For detailed information on the programming API aspect of these samples please refer to the EyeLink Programmer s guide Each sample experiment can be launched from the Start Programs SR Research EyeLink Programming Runtime API GDI or SDL Examples menu item All sample experiments have the following key shortcuts that can be used from the Display PC keyboard These keys are available after the experiment has started and a Data File name has been entered ENTER View camera or accept Calibration Validation if Calibration Validation has just been performed select the zoomed or global camera view Perform Calibration Perform Validation p SS otart experiment A Simple This experiment is the most
87. d button or the A key when the camera image is selected The pupil of the eye should be solidly blue with no other color in the image when the thresholding is properly set If large areas are colored the subject may have blinked press Auto Threshold again If the subject wears eyeglasses reflections may block the pupil in the image If the eyeglasses have an anti reflective coating image contrast may be poor and pupil tracking may be noisy These reflections are automatically reduced as much as possible by the EyeLink system however please be advised that not every subject with glasses will be usable The pupil threshold should be checked by looking at the area within the green box in the image Figure 3 17 shows the symptoms to look for If the threshold is too low the blue area will be smaller than the pupil and the eye tracker data will be excessively noisy If the threshold is too high there will be shadows at the edges and corners of the eye especially when the eye is rotated Adjust the pupil threshold by using the pupil threshold adjustment buttons or with the fl and Keyboard Shortcuts a mnemonic is to think of the key as increasing the blue area and the key as decreasing the blue area lr gt gt Threshold Too High Noisy Good Pupil Threshold Threshold too Low Shadows Figure 3 17 Symptoms of Poor Pupil Threshold The Camera Setup display is updated very rapidly so noise shadows etc wil
88. d Shortcuts S go to Set Options Exit EyeLink Click to quit the EyeLink 1000 Host PC application Keyboard Shortcuts Ctrl Alt Q Exit EyeLink Help F1 Click to access the online help page for the Offline screen All available key shortcuts are also listed on the Help screen Keyboard Shortcuts F1 open Help screen 2 3 1 3 Offline Screen Key Shortcuts go to the Camera Setup screen go to the Output screen go to the Set Options screen Ctrl Alt Q exit the EyeLink Host PC application F1 view the Help and key shortcuts for the Offline screen 2 3 2 Set Options Screen 2 3 2 1 Set Options Screen Purpose The Set Options screen allows many EyeLink 1000 tracker options to be configured manually This is useful when doing manual recording sessions that are not driven by a Display PC using the EyeLink API or to override or manipulate options not set by the Display PC application Ideally all settings to be crucially controlled are set by the Display PC application at runtime via a set of API calls EyeLink 1000 Host Application 2005 2009 SR Research Ltd The Default Settings should be sufficient for many tracking applications Calibration and Validation Conf Igurat ton Set O tions TT HE 4 Ma 2 re Select Conf ig p Alibration Type E iim an 2 as H er ol I D Link Closed Pacing Intereal Welp Fi Settings I Fupll Sise Bate ME AREA oo n
89. dialog will appear on the Display PC asking you to enter a Track EDF file name Enter TEST without the quotes Once TRACK is running control is either from the Host PC or Display PC keyboard and the application will reflect the state of the EyeLink 1000 software by drawing appropriate graphics on the Display PC The advantage of the An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd Display PC based control is that it allows the operator to work near the subject or for self setup We will perform most of the EyeLink 1000 setup by using the Host PC keyboard 3 1 The Camera Setup Screen The first step in an eye tracking session is to set up the participant and eye tracker Begin by navigating to the Camera Setup screen You will see two camera image windows in the middle of the display a global view of the tracked eye on the top and a zoomed view at the bottom Navigation buttons to access other Tracker screens are on the right while selection buttons for tracking mode and other functions are on the left of the screen Image Thresholds Cam era Setup TCI P Link Open Qr Pupil Cornea PEL Sune jel jel Exit Setup Tracking Mode a Nitputzhecord Sample Rate l Set Options 259 500 ik Pupil Tracking IMAGE NOT AUATLABLE Ualidate Drift Check p Image Display EYE NOT AVAILABLE Eye Tracked Illuminator Pouer EA ES Figure 3 1 Example Camera
90. e Information 18 Once the camera is set up the experimenter should monitor the thumbnail camera images at the lower left corner of the tracker screen when in the Offline Calibrate Validate Drift Correct Output and Record screens seeFigure 3 12 The two dots in the middle panel reflect the ever changing target and eye positions in the global camera image For reliable tracking both dots should stay within the red box If they fail to do so adjustment of the camera s view of the subject is advised hee FP 86a T 1334 CR 2030 565 mm 4 Figure 3 12 Target and Eye Positions in the Thumbnail Camera Images Now proceed to section 3 7 Calibration Don t forget to remove the target from the subject s forehead at the end of the recording session An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd 3 2 5 Primate Mount Participant Setup Monocular Most of the details for Primate Mount setups are documented in the Installation Guide Once a physical setup is established there is unlikely to be much variation in the steps taken to track eye movements as there is generally little variability in the view of the eye or the participants The software configuration steps for use of the Primate Mount are similar to the Tower Mount with the exception that the primate mount allows monocular and binocular recording whereas the Tower Mount is limited to monocular recording Similarly while t
91. e chair The user supplies an infrared reflecting hot mirror to project the viewer s eye to the camera This allows accommodation of a wide range of unique viewing setups with very small space requirements A typical setup appears in the diagram at the right side of Figure 1 4 Figure 1 5 EyeLink 1000 LCD Arm Mount Introduction 2005 2009 SR Research Ltd The EyeLink 1000 LCD Arm Mount Figure 1 5 is a fully adjustable arm holding a 17 LCD monitor with the camera and illuminator mounted beneath it When fixed on a sturdy table the entire apparatus can be moved in place in front of the viewer to allow access to difficult to track populations or simply to hold the eye tracker at an appropriate height to accommodate a sitting viewer The EyeLink 1000 Long Range Mount Figure 1 6 consists of a Base holding a Mounting Bar to which a Long Range Illuminator and the Fiber Optic EyeLink 1000 Camera can be attached The Mounting Bar can be affixed to a tripod or the supplied Base at distances up to 150 cm from the eye The entire apparatus was designed to minimize metal content in an effort to provide unprecedented eye tracking capabilities in EEG MEG and MRI environments Figure 1 6 Typical EyeLink 1000 Long Range Mount Configuration Introduction 2005 2009 SR Research Ltd 1 3 System Specifications 1 3 1 Operational Functional Specifications Desktop and LCD Arm Tower Primate Mounts Mount Mount Base Remote Option System
92. e enabled EyeLink 1000 Host Application 2005 2009 SR Research Ltd 2 3 6 2 Drift Check Drift Correct Screen Main Functions Camera Setup Click to go to the Camera Setup screen Keyboard Shortcuts ESC Help F1 Click to view Help Keyboard Shortcuts ENTER Abort Stop the Drift Check Restart Restart the Validation process Auto Trigger Not Used Accept Press to accept fixation value after the participant s gaze Fixation is stable on the target Keyboard Shortcuts ENTER Spacebar Accept Fixation 2 3 6 3 Drift Check Drift Correct Screen Key Shortcuts Key ENTER or Begins or accepts if stable Spacebar ESC Rejects drift correction value if one has been created or exits drift sequence Fl Help screen 2 3 7 Output Screen 2 3 7 1 Output Screen Purpose The Output screen is used to manually track and record eye movement data EDF files may be opened and messages added or data may be output via the optional Analog output card Data file contents are controlled from the Set Options screen Recording may be manually started from the Output screen or by an application via the Ethernet link Manual recording may be terminated by switching back to the OUTPUT screen EyeLink 1000 Host Application 2005 2009 SR Research Ltd 1 Output Camera Setup set Opt lon LT UG HECOHD FOPIL EDF File fad Rersage MT lr ing Right Eye 1008 He Fupil CH
93. e illuminator for an extended period of time as this may result in discomfort and unnecessary exposure to heat and high levels of IR light Important Information 2005 2009 SR Research Ltd The light output of the illuminators may change slightly for a period after power is turned on to the camera and illuminators For applications where illuminators level is critical it is recommended that at least 10 15 minutes be allowed for the illuminators to reach a stable temperature before use This warm up period will also allow the camera circuitry to reach its operating temperature resulting in best image quality at low light levels 6 2 Servicing Information WARNING Changes or modifications to camera illuminators or cables not expressly approved by SR Research Ltd could void the user s warranty and authority to operate the equipment This includes modification of cables removal of ferrite chokes on cables or opening cameras or illuminators WARNING Opening or modifying camera or illuminators or power supply substitutions will void the warranty and may affect the safety compliance of the system No user serviceable parts inside contact SR Research for all repairs CAUTION Use of controls or adjustments or performance of procedures other than those specified herein may result in hazardous radiation exposure 6 2 1 Non Serviceable Components In the event of failure the camera and illuminators should be replaced as a unit a
94. e sample data command which is followed by a list of data types to include A single keyword is included for each type Keyword Data Type LEFT Sets the intended tracking eye usually include both LEFT and RIGHT RIGHT GAZE includes screen gaze position data GAZERES includes units per degree screen resolution at point of gaze HREF head referenced eye position data HTARGET target distance and X Y position EyeLink Remote only PUPIL raw pupil coordinates AREA pupil size data diameter or area BUTTON buttons 1 8 state and change flags STATUS warning and error flags not yet supported INPUT input port data lines not yet supported The default data is file sample data LEFT RIGHT GAZE GAZERES AREA STATUS Usually data for both eyes is enabled and the menus in the EyeLink 1000 tracker are used to set which eye is actually tracked Recording of gaze and pupil area is essential for most work and resolution is important if velocity is to be computed later Recording of HREF data is optional For the EyeLink Remote the HTARGET flag should always be included in the recording file sample data LEFT RIGHT GAZE GAZERES HTARGET AREA STATUS 4 6 2 Event Data Data Files 2005 2009 SR Research Ltd Eye movement events are generated by processing one of the types of eye movement data PUPIL HREF or GAZE as specified by the recording parse type command the default setting is GAZE This command may be edited in the DE
95. e subject is recommended 9 Start the Host PC application and go to the Set Options screen If your system is licensed for remote eye tracking you should now see Desktop Remote or Arm Remote as one of the Configuration options Select your mount type and then go to the Camera Setup screen 6 Ensure the lens cap has been removed from the camera by pulling it outwards while holding the camera A camera image should now be displayed on the global view of Camera Setup screen on the Host PC Ask the subject to be seated Adjust the height of the chair so that the subject is comfortable and his her line of sight is to the upper half of the monitor Adjust your mount position so that the image of the eye appears in the center of the global view of the camera image INC Prose rds Camera Setup P TCF IF Link Open Pupil Corneal Screens CI P is d Off linc Tracking Mimie A j mum Sanpl Mate p Ea aN Pupil Tracking EUA Inage Display GB a aaa Drift Correct Target Thre idz Distance 524 6 mnn TUTTA Figure 3 8 Camera Setup Screen with the EyeLink Remote An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd 7 The EyeLink Remote uses a small target sticker placed on the participants forehead This allows tracking of head position even when the pupil image is lost i e during blinks or sudden movements For the largest lateral movement range of the subject track
96. e tracking functionality including subject setup calibration sending real time data through an Ethernet link or optional analog output card and data recording e can be configured remotely via commands sent over the Ethernet link e can show real time feedback of eye data during calibration or recording allowing other network devices to be devoted to accurate stimulus delivery Availability of some sampling rates depends on the mount type and system version Introduction 2005 2009 SR Research Ltd 1 2 2 Display PC The EyeLink 1000 Display PC administers the eye tracker calibration directs data collection and presents stimuli during experiments On line eye and gaze position can be received from the EyeLink Host PC via the Ethernet link making gaze contingent paradigms possible The user can acquire the optional SR Research Experiment Builder to assist in creating sophisticated EyeLink experiments on 32 bit Windows 2000 XP or Vista without programming everything from scratch For users who wish to program their own experiments a wide range of programming options exist for assisting in automated data acquisition on the Display PC A C C programming API with example code exists for Windows Mac OS X Linux and other operating systems Additionally third parties have made several methods freely available to use the EyeLink with other software such as MATLAB PC and MacOS via the Psychtoolbox Presentation and E Prime O
97. ecording Screen On line Offset correction Plot Mode Only Recording Screen PP Pause or resume plotting also marks HOME Clear all data Undo last view or gain offset change Change to default view or gain offset Fit all data to view auto gain offset adjusting Selects offsets or scrolling when used with CTRL mouse or fl and keys Selects gain or zooming when used with mouse ALT or and keys Load or Save Analog or raw Gain and Offset 2 3 8 5 Example Gain and Offset Adjustments Imagine a simple saccade task which displays a target along the horizontal meridian left center right you plan to send out 4 volt output when the EyeLink 1000 Host Application 2005 2009 SR Research Ltd subject fixates on a target appearing on the left end of the display and 4 volts when the subject fixates on the target on the right end 1 2 3 4 5 6 7 8 Go to the Set Option screen Set the Record View as Plotting and Plot data type as Analog If you don t have an analog card installed on the EyeLink Host PC set the Plot data type to RAW Start the EyeLink recording Present three targets at the left end right end and center of the screen each for 5 seconds and instruct the subject to fixate on the targets as stably and precisely as possible If you do not have a program ready you may mark the target positions on a cardboard and use the cardboard as the display
98. ection or if the eye image is clipped by the side of the camera window the crosshair and ellipse fitting will disappear and the pupil will be lost On the Host PC a red warning message will appear below the small camera image for the eye indicating No Pupil 14 The EyeLink Remote exclusively uses Pupil CR mode The CR if present is identified by a filled turquoise or yellow white circle marked by a crosshair The CR threshold value and bias are displayed under the zoomed camera view The CR threshold is updated automatically and CR biases can be manually adjusted using buttons or the and keys Heuristically CR biases should range from 0 9 to 1 1 a value around 1 0 is recommended Once the threshold bias is adjusted have the subject slowly look along the edges of the display surface and ensure that the corneal reflection does not get lost If the CR does get lost a red warning message will appear below the small camera image for the eye indicating No CR on the Host PC 15 By default the Illuminator Power level of the EyeLink Remote is set to 100 If the Desktop Mount is placed too close to the participant or if the CR signal is not reliably acquired you may consider lowering the illumination level to 7596 One sign that illumination may be set too high is pupil authothreshold values above 120 16 The EyeLink Remote draws a red search limit box that is automatically updated with changes in pupil position This search
99. ects may show substantial drifts in gaze position during fixations or may not fixate carefully adding to the errors To begin the validation procedure select the Validate button or press the V key in the Camera Setup screen The Host PC display will show the gaze position as a round colored cursor Note the movements of the cursors and the change in relative horizontal position vergence following saccades Once the cursor appears stable and close to the target press the J ENTER key to accept the first fixation The remaining points are collected automatically or manually as in the calibration process As each fixation is collected a cross is used to mark its computed position relative to the target The error in degrees is printed next to the cross Similar to the calibration procedure the user can use the Backspace key in the middle of a validation sequence to redo data collection for the last or last few validation points collected After the final fixation is collected the average and worst errors are displayed at the bottom of the screen and the accuracy is scored An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd Each eye is graded separately using colored messages similar to the calibration results GOOD green background Errors are acceptable FAIR grey background Errors are moderate calibration should be improved POOR red background Errors are too high for useful eye trackin
100. efore it disappears If automatic sequencing has been enabled targets will be presented and fixations collected without further intervention Each time a new target is displayed the subject quickly makes a saccade to it The EyeLink 1000 system detects these saccades and the fixation following producing an automated sequencing system NOTE Sequencing may halt if the setup of the eye causes pupil loss or noise at the target position If this happens adjust the threshold and restart the calibration by pressing the ESC key Press it twice once to restart and again to exit to return to the Setup menu Even though the calibration is automatic watch the Host PC s display carefully Note the position of the cross shaped pupil position markers these should form a grid shape for the 9 point calibration Lapses of subject attention will be clearly visible in the movements of this cursor Also visible will be any difficulties the subject has in fixating targets and most camera setup problems The following figure illustrates a good calibration left panel and a poor calibration right panel An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd Good Calibration Poor Calibration Figure 3 20 Calibration Grid For some subjects especially those with neurological conditions short fixations or lapses of attention can make the automated procedure unusable A manual calibration mode can be used for these
101. emaining port NOTE Please check the height of the EyeLink 1000 Tower before having a subject seated ideally this should have the top of the display at about the same height as the forehead rest The Tower height adjustment should only need to be done during initial system setup and not on a participant to participant basis An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd Before adjusting the camera image check the mirror angle of the system If the subject does not wear glasses set the mirror angle to the lowest position i e loosen and move the mirror angle adjusting knobs to a position away from the subject and then tighten the knobs This mirror angle will be compatible with most of the subjects On the Camera Setup screen also uncheck the Use search limits button This allows the tracker to search for pupil position across the whole camera image in case the pupil position is lost IMPORTANT The height of the EyeLink 1000 Tower should not be adjusted when a subject is using the head support device If the subject wears glasses start with the mirror angle to middle or high position and then gradually adjust it during the camera setup process if necessary The Use Search Limits button should also be checked so that the tracker will try to re acquire the pupil position within a red box illustrated in the global view of the camera image Please note that the EyeLink 1000 Tower mount is not
102. ength 6 2 4 Power Supply Replacement The EyeLink 1000 camera requires a power supply that is rated for 12V and 2A or higher This supply must have a 2 5mm coaxial barrel power connector 5 5 x 2 5 x 9 5mm For safety reasons the power supply must have EN 60950 UL 1950 CSA 22 2 No 950 or other equivalent safety approval The power supply should also be labeled Class 2 or LPS for compatibility with the latest safety requirements SR Research can provide replacements if required or a list of approved power supplies It is important to ensure that the power supply has a ferrite the black ring on the cable near the connector in order to prevent electronic interference being generated If the new power supply does not have such a ferrite this should be moved from the old to the new cable and clamped to the cable within 10 cm of the camera WARNING See the Specifications section for information on the power supply requirements Use of a power supply with incorrect polarity voltage or other ratings may cause safety hazards void the user s warranty or damage system components Important Information 2005 2009 SR Research Ltd 6 3 Limited Hardware Warranty SR Research Ltd 9516 Main St Osgoode Ontario Canada KOA 2WO EyeLink 1000 Product Hardware Limited Warranty SR Research Ltd warrants this product to be free from defects in material and workmanship and agrees to remedy any such defect for a p
103. ens stabilized Head Binoc Monoc 25mm lens stabilized Head Keyboard Shortcuts F8 provide the dialog box with options up and down cursor keys move selection among available configurations Enter selects Compress EDF Files EDF Fil Compress EDF files on line so they use less disk ee abe space This cannot be changed while a file is open Keyboard Shortcuts F9 Compress the EDF file EyeLink 1000 Host Application 2005 2009 SR Research Ltd File Data Contents Selecting Samples will record data samples to the EDF file and selecting Events will record on line parsed events Keyboard Shortcuts F alternates selection of Samples and Events buttons Rav Eve Position Record the raw x y coordinate pairs from the camera to the EDF file Keyboard Shortcuts 3 toggle record Raw Eye Position on off aie Record head referenced eye rotation angle HREF to HREF Position the EDF file Keyboard Shortcuts 4 toggle record HREF Position on off Record gaze position data in the EDF file Keyboard Shortcuts G toggle Gaze Position record on off Button Flags Record EyeLink button status on each sample in the EDF file Keyboard Shortcuts B toggle Button Flags record on off Record external device data from the parallel port or EyeLink Analog Card on each sample in the EDF file Keyboard Shortcuts I toggle Input Port Data record on off z Click to view previous screen Preuious Screen Keyboard Sh
104. ent and data description lines Each line begins with a keyword identifying the type of data in the rest of the line 4 9 1 ASC File Structure For sample only ASC files file structure is very simple These files are produced using the s or ne options of EDF2ASC and only sample data lines are present There is no data on what type of eye position data or which eye produced the data Recording blocks are separated by samples lines consisting of missing value data dots or the string specified with the miss option Gaps in the sequence of sample timestamps may also be used to determine sample block divisions Data Files 2005 2009 SR Research Ltd For ASC files containing events and optionally samples the order of lines is carefully structured The order of items in an ASC file is similar to that of a sorted EDF file The file begins with a copy of the EDF file s preamble with each line preceded by The preamble reports the file version date created and any description from the application Usually the preamble is ignored during analysis The sequence of events and samples in the ASC file follows strict rules These are e START events mark the beginning of each recording block and END events mark the end of each block The START events also specifies which eye s data is present and if samples events or both are present e Data specification lines follow each START event These specify the type of data in sample
105. eral data fields Data for each event is compressed and an extendable data format allows compatibility with future expanded file formats Note that not all the event data listed here is available through the EDF2ASC translator program 4 5 1 Messages The most flexible event type is the message event A message is most often text but can contain any type of binary data as well up to a maximum of 300 bytes Messages are created by application software and forwarded over the link to the EyeLink tracker which timestamps the data and writes it to the EDF file The application does not need precise time keeping since link delays are usually very low on the order of 1 or 2 milliseconds Message events are used for two main purposes They serve to precisely record the time of important events such as display changes subject responses etc They also record experiment specific data such as trial conditions Message events consist of a millisecond timestamp and the message data A message is most often text but can contain any type of binary data as well For text data a zero byte at the end of the text is recommended for compatibility with applications written in C A message data length field provides Pascal string compatibility and allows binary data to be recorded in the message Current EyeLink applications only support text messages with zero terminated strings It is also recommended that messages be shorter than 120 characters 4
106. eriod as stated below from the date of original installation EyeLink 1000 High speed Camera One 1 year parts and labor EyeLink 1000 Illuminator Module One 1 year parts and labor EyeLink 1000 Head Support System excluding gel pads One 1 year parts and labor High speed PCI Frame Grabber One 1 year parts and labor LIMITATIONS AND EXCLUSIONS This warranty does not apply to any product which has been improperly installed subjected to usage for which the product was not designed misused or abused damaged during shipping or which has been altered or repaired in any way that affects the reliability or detracts from the performance Any replaced parts become the property of SR Research Ltd Computer system components used with the EyeLink 1000 system are excluded from this warranty unless expressly agreed to be otherwise in writing by SR Research Ltd contact the original computer manufacturer for service and support of computer components This warranty is extended to the original end purchaser only Proof of original date of installation is required for warranty service will be performed This warranty does not apply to the software component of the product THIS EXPRESS LIMITED WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES EXPRESS OR IMPLIED EXCLUDING ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE IN NO EVENT WILL SR RESEARCH LTD BE LIABLE FOR ANY SPECIAL INDIRECT OR CONSEQUENTIAL
107. error message SIZE highlighted in yellow indicates that the size of the pupil is too large or too small This should not occur when the camera is mounted on the EyeLink 1000 Tower as the camera to eye distance has been carefully calculated to ensure compatibility with a wide range of different pupil sizes For the EyeLink Remote the pupil SIZE warning typically suggests that the pupil size is too small because of the ambient lighting or the eye tracker is placed too far away from the subject The pupil status error message MISSING highlighted in red indicates that the pupil is missing from the camera view This could be that the participant is blinking It could also be that there is a problem with camera setup Please adjust as needed Indicates Status of Corneal OK Corneal is visible MISSING Corneal is missing The corneal status error message MISSING highlighted in red indicates that the corneal reflection is not visible to the camera See section 3 4 for details on how to set up corneal reflection properly All status flags remain on for a minimum of 200 msec even if the condition that caused the warning or error to be raised lasted for less than 200 msec 3 8 Validation It is important that problems with the calibration be identified and corrected before eye movement recordings are ruined By running a validation An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd immediatel
108. et in the Set Options screen For example when plotting raw eye position the data are normally within a range between 30000 and 30000 The two purple bands at the top and bottom portions of the display represent data that is out of normal range The visibility of the x and y eye traces can be controlled by the x vis and y vis buttons under the show section at the bottom of the plot For calibrated data types GAZE HREF and Angle the user can change the layout of the plot by clicking on the zoom and scroll buttons The plotting scale can be changed by clicking on the fl and l buttons in the Zoom section so that fine details or global patterns of the x y traces can be viewed The position where the traces are displayed can be changed by clicking on the ff and U buttons in the Scroll section For RAW and analog outputs the user can adjust the gain and offset values and therefore this provides a way for the user to calibrate data in the recording screen This might be useful for experiments with primates or patients where the 9 point calibration method is not possible Please note that additional buttons and gain offset feedback values are available when the recording data type is set to RAW or Analog The SEL buttons under the Adjust menu allows the user to select or unselect either or both eye traces for adjustment For the ease of adjustments user may select one eye tr
109. f the eye especially when the eye is rotated Therefore it is important that the experimenter have the subject look at the corners of the monitor and watch for potential pupil image problems One common problem is for shadows at the corners of the eye which can disrupt tracking of the pupil 12 In the zoomed camera image the threshold values for pupil and corneal reflection are displayed under the camera image Unlike other versions of the EyeLink 1000 eye tracker these threshold values are automatically updated The number beside the pupil threshold value is pupil bias the extent to which the pupil threshold is modulated see Figure 3 10 The user may adjust the bias using the pupil threshold adjustment buttons or with the UP and DOWN keys Raising the bias increases pupil coverage i e increasing the blue area while lowering the bias decreases the pupil coverage i e decreasing the blue area Heuristically pupil biases should be in the range of 0 9 to 1 1 A value around 1 05 is recommended though this will vary depending on the eye An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd 13 The operator can easily tell if the pupil has been detected because the image on the Host PC will have a crosshairs indicating its center A green ellipse updated each refresh is drawn around the elliptical pupil fitting algorithms see section 3 6 Pupil Tracking Algorithm If a shadow interferes with pupil det
110. fore each trial to ensure that accuracy of the calibration parameters is maintained Generally this is initiated via the application running on the Display PC Keyboard Shortcuts D go to Drift Check screen Video Setup Click to go to the Video Setup screen See EyeLink Video Overlay Option User s Manual for details This button is useful only if your system has been licensed for video overlay option Keyboard Shortcuts W Video overlay configuration 2 3 3 3 Camera Setup Screen Key Shortcuts Go to the Offline screen or exit Camera Setup ENTER Toggles sending images over link EyeLink 1000 Host Application 2005 2009 SR Research Ltd D JGototheDrift Check Correct screen _ o lt O j GototheOutputscren SS O Open the Help dialog in the help screen there is a brief overview of the role of this page and the key functions for it Ctl Alt Q Ctrl Alt Q Exit the EyeLink Host application Page Up and fl Increase pupil threshold bias Page Down Decrease pupil threshold bias and Set corneal reflection threshold bias select Eye Global or zoomed view for link A Auto threshold selected imageTower MountDesktop Mount Additionally for the EyeLink Remote realigns the search limit box on top of the current eye position E Cydethrougheye s totrack o Li Select left eye for recording o 000 y R Select Right eye for recording o 0 y B Seletbotheyesforrecordng
111. g Observe the pattern of the errors for each of the targets If only one target has a high error the subject may simply have mis fixated that point and the validation may be repeated to check this press ESC to return to the Camera Setup screen and V to repeat the validation If a regular pattern is seen i e all fixations on the left side are too low there was probably a calibration or camera setup problem In this case press ESC to return to the Camera Setup screen and re calibrate 3 9 Improving Calibration Quality The quality of calibrations determines how useful the data recorded will be and how accurate the gaze calculation will be Try some of these simple procedures to improve data quality and gaze accuracy e The threshold pupil area must be inside the pupil box displayed as a red box around pupil when the subject is looking at any area of the display If a portion of the pupil exits this box the pupil will be lost e The corneal reflection should never be lost or misidentified when the subject looks around the calibrated area e Always ask the subject to look at the four corners of the display after performing the camera setup Watch for the warning signals on the tracker screen to make sure that the pupil and CR signal is not lost when the subject is doing so e Subjects who have never been calibrated before require some practice in stably fixating the calibration targets Try to perform at least two cali
112. get and Eye Positions in the Thumbnail Camera Images 61 2005 2009 SR Research Ltd EB Figure 3 13 Position and Angle of the Camera for EyeLink 1000 Desktop Monocular vs Binocular Mount cc cccecc cece eee ee ene eneeeeeneeeeeeneeenenseneenees 63 Figure 3 14 Camera Setup Screen Desktop Mount Angled Binocular Mc 6 8 qc goa een ee E es ene en eee ee reer 64 Figure 3 15 Camera Setup with Subjects Wearing Glasses Desktop Mount CAC PA n nbled eE recess sate recast dons EEE ect DORUM aude 65 Figure 3 16 Adjusting the Orientation of the Camera Image 66 Figure 3 17 Symptoms of Poor Pupil Threshold cece cece eee eee eeeeeeees 68 Figure 3 18 Corner Effects Seen with Head Rotation eceeeeeeesee 69 Pisure 9 19 Corneal Relle CtIODG o icosinceaizacsesstmcdeceacsensimcaereacniees MUFIERUU E REP CHARME 70 busco 20 Calibration CITICI acccansanatesssansnteeces rae eteeniteneneaeapaparententmatenseauets 74 Figure 3 21 Performing On line Drift Correction with Mouse Click 80 List of Tables Table 1 Lens Guide for Different Viewing Distances seesrereesesessssseseseeo 22 Table 2 EyeLink 1000 Configuration Files eeeeseeeseeeee ene 44 Table 3 Analog Channel Data Assignments for the EyeLink 1000 hardware 122 mS 2005 2009 SR Research Ltd 1 Introduction This section introduces the technical capabil
113. gurations differ in the type of mounting used for the EyeLink 1000 high speed camera and low output infrared illuminator module With the exception of the Long Range Mount the mounts work with both the Standard or Fiber Optic EyeLink 1000 Camera The EyeLink 1000 Desktop Mount Figure 1 2 sits below the display the participant views during the experiment There are two different Desktop Mounts one with the illuminator on the right pictured in Figure 1 2 and one with the illuminator on the left The Desktop Mount supports monocular binocular and Remote monocular eye tracking at a variety of sampling rates depending upon the licensing options purchased The Desktop and Long Range Mounts enable binocular recording for human participants Figure 1 3 EyeLink 1000 Tower Mount Introduction 2005 2009 SR Research Ltd The EyeLink 1000 Tower Mount Figure 1 3 incorporates the camera and illuminator housing within a combined chin and forehead rest via an infrared reflective mirror Mirror angle and chin position are adjustable for increased compatibility with eyeglasses The Tower Mount affords the largest field of view of all mounting systems for the EyeLink 1000 high speed camera Figure 1 4 EyeLink 1000 Primate Mount and Diagram of a Typical Setup The EyeLink 1000 Primate Mount Figure 1 4 left houses the camera and an infrared illuminator in a compact bracket that can be affixed to a vertical surface such as a primat
114. he EyeLink 1000 tracker and most data acquisition systems rely on interrupt driven software sampling and output it is possible that time base jitter could result in missed samples or repeated recording of a single eye position sample This would appear as a step artifact in rapidly changing eye position data such as saccades or pursuit 7 6 1 Strobe Data Input The best time base method is to use the EyeLink 1000 analog output strobe which is assigned to digital output D7 on the analog card connection board This signal can be configured to be a short or long trigger pulse which can be used to trigger hardware data acquisition on analog input devices equipped for Appendix A Using the EyeLink 1000 Analog and Digital Output Card 2005 2009 SR Research Ltd this or to trigger interrupt driven acquisition The characteristics of this strobe pulse may be set in the ANALOG INI file with the strobe being active high or active low and with duration between 5 and 2000 microseconds The onset of the strobe is also delayed from the time that analog outputs change in order to allow outputs to settle to the new voltages A delay of 400 microseconds is standard allowing the use of signal conditioning low pass filters as discussed earlier 7 6 2 Oversampling and Toggle Strobe Another possibility is to over sample the analog output by recording the analog outputs at more than twice the EyeLink 1000 sample rate This will prevent missed s
115. he Tower Mount is limited in its use of a single 25 mm lens users of the Primate Mount may wish to use the 16 or 25 mm lens according to the table below Lens focal length Distance Camera Front to Eye Field of View 240 280 mm 85 x 65 mm 350 400 mm 85 x 65 mm 3 2 6 Desktop Mount Participant Setup Binocular Before the subject is seated make sure that the EyeLink 1000 Desktop Mount is already set up for binocular tracking 1 Make sure version 3 0 or above of the EyeLink 1000 host software is running on the Host PC Tracker version information is displayed on the Offline screen of the host software 2 For a binocular Desktop Mount check whether the 25 mm lens with a long focusing arm or a large wheel has been installed The 35 mm lens without a focusing arm may also be used at a further distance 3 Check whether the camera is set to the oblique position the elongation of the camera should form a 45 degree angle relative to the table see the figure below If not please loosen the Camera Screw at the front and move it to the bottom end of the slot Rotate the camera until its elongation forms a 45 degree angle relative to the table and then tighten the screw Note that dimples in the camera align with protrusions on the mount to ensure the camera is in the right position 4 The Desktop Mount should be placed at a distance of 40 to 70 cm from the observer measured from the front end of the Camera Screw to the rear
116. he camera image is missing or severely distorted by eyelid occlusion Only the time of the start and end of the blink are recorded Blinks are always preceded and followed by partial occlusion of the pupil causing artificial changes in pupil position These are sensed by the EyeLink 1000 parser and marked as saccades The sequence of events produced is always e SIARTSACC e SIARTBLINK e ENDBLINK e ENDSACC Note that the position and velocity data recorded in the ENDSACC event is not valid All data between the STARTSACC and ENDSACC events should be discarded The duration of the blink may be computed by either the duration of the missing pupil between the STARTBLINK and ENDBLINK events or the difference between the ENDSACC and STARTSACC events in the sequence Data Files 2005 2009 SR Research Ltd Fixation immediately preceding and following blinks should be examined carefully as they may have been truncated or produced by the blink process Discarding fixations shorter than 100 ms proceeding or following blinks will eliminate most artifacts 4 6 Setting File Contents The data recorded in samples and events may be set in the EyeLink 1000 configuration file DATA INI or by sending commands to the tracker across the link via the API eyecmd_printf Similar commands exist for samples and events sent over the link for real time applications 4 6 1 Sample Data The sample data written to the EDF file is controlled by the fil
117. he experimenter There are two ways of performing an online drift correction during recording If it is very likely that the subject will look at a particular point across trials a reference position for drift correction could be defined at that position This can be done by editing the value of online dcorr refposn in the CALIBR INI or FINAL INI file under C ELCL EXE directory of the Host PC or more preferably by sending this as a command in your program When the subject looks at the reference position pressing F9 key on the Host PC or sending an online dcorr trigger command over the link will perform the drift correction Alternatively an online drift correction can be performed with the aid of a mouse click Before recording add the following line to the FINAL INI file Normal click dcorr ON This will bring up an additional clickable drift correction button in the record screen Click on the Drift Corr button which will flash periodically if enabled Move the mouse cursor over the intended drift correction target and instruct the An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd participant to fixate the target precisely Press the button only once when the participant fixates stably The drift correction may fail if there is no stable fixation data or if there is a large error between the current fixation and the target item By default the maximum acceptable error value set by the on
118. height of the chair so that the subject is comfortable and his her eye line is aligned to upper half of the monitor Ask the subject to lean her his forehead against the forehead rest and adjust the height of the chinrest so that the subject s chin sits comfortably on the chin rest pad If necessary loosen the Lock knob on the Desktop Mount to adjust the angle of the camera so that the eye to be tracked appears in the center of the global view of the camera image If the camera does not stay as configured tighten both the Friction knob and the Fest Lock knob once the vertical position of the eye is in the intended camera image IMPORTANT If the camera image is tilted 45 degrees counterclockwise please check whether the Configuration setting in the Set Options screen is set to Desktop Level If the camera image is tilted 45 degrees clockwise check whether the camera is set to the horizontal position on the Desktop Mount If the camera image is rotated 180 degrees then your Host PC software is probably for the wrong Desktop mount please update your Host PC software from the support website and choose the Host PC software based on whether your illuminator is on the left or right hand side of the mount In the global view window the eye to be tracked should appear in the center of the camera image whereas the untracked eye should appear near the edge or outside of the camera view Move the Host PC mouse cursor on top of the p
119. hortcuts F6 select view to show on the Record screen Plot or Gaze Cursor view F7 in Plot view select the type of data to plot 2 3 2 3 Set Options Screen Key Shortcuts Calibration Type selected Pacing Interval for automatic calibration and validation target sequence presentation R Randomize calibration and validation target order Autodetect the eye to be track Mirror Mount Lock the currently selected eye Desktop Mount Angled X F2 F3 File data contents selection Raw eye position in samples HREF eye position in samples I EyeLink 1000 Host Application 2005 2009 SR Research Ltd Select Record view plot or gaze cursor Select to view video setup screen if the overlay option is enabled Select Record Plot Data Type jew vi O toggle on off video overlay option ENTER Camera Setup screen Return to previous screen HELP screen Revert to configuration from last session This is still saved even when the PC is turned off D Load default configuration DEFAULTS INI 2 3 2 4 Lens Guide for Different Viewing Distances FO F7 SC 1 The EyeLink 1000 has a versatile camera that can be fitted with different lenses to accommodate different eye to camera distances The table above indicates recommended lenses for different mounts and distances The lens is one consideration in determining suitability of a particular mount for an eye tracking application but the illumination source
120. il CH S TAIILE Validation 10 paints Foluwt 1 of 10 Figure 2 7 Validate Screen 2 3 5 1 Validate Screen Purpose The Validate screen displays target positions to the participant and measures the difference between the computed fixation position and the fixation position for the target obtained during calibration This error reflects the gaze accuracy of the calibration The functionality available in the Validate screen is very similar to that of the Calibrate screen Validation should only be performed after Calibration To perform a validation have the subject look at the first fixation point and press the Accept Fixation button or the ENTER or Spacebar key to start the validation If Auto Trigger is not enabled repeat this action after each target fixation If the accuracy at a fixated position is not acceptable you may choose to perform a Calibration again and then recheck fixation accuracy by revalidating 2 3 5 2 Validate Screen Main Functions Camera Setup Click to go to the Camera Setup screen Keyboard Shortcuts ESC Camera Setup Help F1 Click to view the help menu for the Validate screen Keyboard Shortcuts F1 Help EyeLink 1000 Host Application 2005 2009 SR Research Ltd Click to reject the Validation value given and revert to the Calibrate screen Keyboard Shortcuts ESC Abort if during Validation Click to Restart the Validation process Click to automate the valid
121. intended configuration file should be used Data Files 2005 2009 SR Research Ltd The following example illustrates how to reparse the TEST EDF file with a new set of parser configurations contained in the PARSER2 INI file and save the output data to TEST NEW EDF ELCL REPARSE TEST TEST NEW C PARSERZ INI 4 4 File Data Types The data contents of an EDF file are organized in two streams samples and events Samples are used to record instantaneous eye position data while events are used to record important occurrences either from the experimental application or from changes in the eye data Both samples and events can report eye data in several forms These are discussed in the description of sample data Eye movement data is parsed by the EyeLink 1000 tracker on line and used to generate eye movement events which are discussed with application messages and button events 4 4 1 Samples samples are records of eye position pupil size and button or input states The EyeLink 1000 tracker can record up to 2000 samples per second in a monocular tracking mode or up to 1000 samples per second in a binocular tracking mode depending on your system configuration and tracker licensing Each sample is stored as a binary record in the EDF file with simple compression used to minimize disk space Even with compression recording 1000 samples per second will create very large EDF files about 15K of data per second Each sample may contain
122. is equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at the users expense WARNING Changes or modifications not expressly approved by SR Research Ltd could void the user s warranty and authority to operate the equipment Introduction 2005 2009 SR Research Ltd 2 EyeLink 1000 Host Application 2 1 Starting the Host Application Turn on the Host PC If your system shows the Windows Boot Manager interface select the default EyeLink partition see left side of Figure 2 1 The Host program will start automatically If you see a System Commander OS Selection screen choose the EyeLink partition by clicking on the OS icon see right side of Figure 2 1 You should see a C gt prompt at the command line Choose an operating system to start or press TAB to select a tool se arrow keys to highlight your choice then press ENTER DP 5D OS Wizard Partitioning i Information Settings Locking Microsoft Windows Vista To specify an advanced option for this choice press F8 Seconds until the highlighted choice will be started automatically 27 ENTER Choose TAB Menu ESC Cancel Auto Select Figure 2 1 Booting into the EyeLink Partition If the EyeLink 1000 Host application doesn t start automatically type the following in the command prompt T ENTER Another way to start the Host application is to go directly into the direc
123. iseconds The X and Y eye position at the start and end of the saccade lt sxp gt lt syp gt exp lt eyp gt are listed The total visual angle covered in the saccade is reported by lt ampl gt which can be divided by dur 1000 to obtain the average velocity Peak velocity is given by pv Optionally the eye position angular resolution in units per visual degree is given as well All samples that are within the saccade will be listed between the SSACC and ESACC events for each eye simplifying data analysis 4 9 3 8 Blinks e SBLINK eye lt stime gt e EBLINK eye lt stime gt lt etime gt dur Blinks periods of data where the pupil is missing are reported by the SBLINK and EBLINK lines The time of the start of the blink is indicated by the SBLINK line which can be eliminated with the EDF2ASC nse option The eye is L or R indicating the eye s data that produced the event The end and duration are given in the EBLINK event Blinks are always embedded in saccades caused by artificial motion as the eyelids progressively occlude the pupil of the eye Such artifacts are best eliminated by labeling and SSACC ESACC pair with one or more SBLINK events between them as a blink not a saccade The data contained in the ESACC event will be inaccurate in this case but the lt stime gt etime and dur data will be accurate It is also useful to eliminate any short less than 120 millisecond
124. ities and supporting documentation for the EyeLink 1000 eye tracker The EyeLink 1000 can be used in several configurations each with its own strengths and capabilities allowing a single base system to suit a wide variety of research applications The same camera technology and software supports all configurations making the EyeLink 1000 the most versatile solution for eye and gaze monitoring available The EyeLink 1000 s high speed camera comes in two varieties Standard and Fiber Optic each with identical eye tracking capabilities The cameras have been designed to interchangeably fit into different mounting options with the exception that the Fiber Optic camera is exclusively used with the Long Range Mount This means that purchase of a single Base System plus an array of mounts allows the same eye tracker to be used in a wide range of settings from high precision recording in the laboratory with the head stabilized to Remote recording without head stabilization to sensitive and specialized recording environments like MRI or MEG settings In all of these modes the unprecedented low noise stability and the world s fastest sampling rates are available The EyeLink 1000 is a truly multipurpose eye tracking solution Each EyeLink 1000 configuration is unified by an identical application programming interface API and EyeLink Data File EDF output allowing experimenters to seamlessly switch between data collection and analysis in different
125. l be easily detected You can have the subject look at the corners of the monitor and watch the pupil image for problems One common problem is for shadows at the corners of the eye which can capture the pupil see the panel on the An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd right These may be eliminated by decreasing the threshold with the key Be careful not to raise the threshold too much as the pupil thresholding may be poor at other eye positions The pupil on the Host screen should have a cross hair drawn around its center indicating that it has been detected If a shadow captures the pupil or it is clipped by the side of the camera window as in Figure 3 18 the crosshair and green box will disappear and the pupil will be lost On the Host PC a red warning message will appear below the small camera image for the eye indicating No Pupil In general after threshold adjustment pupil thresholds should be between 75 and 110 and corneal thresholds should not exceed 230 If the pupil threshold is too low try increasing the illumination output If the pupil threshold or corneal thresholds are too high try reducing the illuminator output IQ Sy C Bados cas Pupil Clipped and Lost Good E pupil captures Figure 3 18 Corner Effects Seen with Head Rotation EyeLink 1000 Desktop and LCD Arm Mount Users If the pupil crosshair flickers on and off or becomes missing even though the
126. lable and when pupil size data is not required The results of all combinations of configurations and monocular binocular eye tracking modes are summarized in the table below with X and Y representing horizontal and vertical position data and P representing pupil size data Appendix A Using the EyeLink 1000 Analog and Digital Output Card 2005 2009 SR Research Ltd 7 4 2 Analog Data Types and Ranges Both gaze and HREF position data are available for analog output These are selectable through the EyeLink 1000 tracker s Set Options menu screen Each of these is scaled to a voltage on the analog output as described below Raw pupil or pupil CR data is also available for applications that implement their own calibrations 7 4 3 Scaling of Analog Position Data Each of the types of position data is scaled to match the selected analog output voltage range Several variables in ANALOG INI set what proportion of the expected data range for each type will be represented at the output and what the total voltage range will be e Total analog voltage range is set by analog dac range followed by the highest and lowest voltage required The voltage range may be from 10 to 10 volts with other typical ranges being 5 to 5 or O to 10 volts e The fraction of the total data range to be covered is set by the analog x range and analog y range variables These are followed by the data type and the minimum and maximum range fraction For example
127. line dcorr maxangle command is 5 0 Plot Uicu Drift Corr furation iseci 13 n Tracking Left Eye 1900 He Pupil Thresholds Data to Link Samples and Events P 72 fea log Output Samples p CR 215 Tithe POMEL E Figure 3 21 Performing On line Drift Correction with Mouse Click 3 12 Exiting the Host Application You can now close the EyeLink 1000 tracker program Press the key combination CTRL ALT Q from any point in the Host PC tracker program to exit to the command prompt 3 13 EyeLink 1000 Setup Summary It is suggested that you try the procedures in this section until you feel comfortable with the EyeLink 1000 setup and can get reliable calibrations This is a summary of the steps detailed in the practice session It assumes no setup problems are encountered e Start the EyeLink 1000 Host application e Start TRACK EXE on the Display PC e Have the subject seated in the chair comfortably Adjust the height of the chair so that the subject s eye line is at the upper part of the monitor An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd e Select the appropriate EyeLink Configuration When using the EyeLink Remote put the target sticker on the subject s forehead and adjust the position angle of the Desktop Mount e Press J ENTER to start Setup mode Press ENTER again to transfer the camera image to the Display PC e Click on
128. lus position during the experiment 4 4 4 Button Data The state of up to 8 buttons or input port bits may be recorded in each sample Button ports bits and polarity may be set in the EyeLink 1000 tracker configuration file BUTTONS INI The button data consists of two 8 bit fields recorded as a 16 bit number The lower 8 bits contain the current status of the 8 buttons bit O if off 1 if pressed Each of the upper 8 bits will be set to 1 if its button has changed Data Files 2005 2009 SR Research Ltd since the last sample The least significant bit in each byte corresponds to button 1 and the most significant to button 8 4 5 Events One of the most significant aspects of the EyeLink 1000 tracking system and the EDF file format is its on line processing of eye movement data to identify and record events such as fixations and saccades This eliminates the need for recording of sample data for many types of research and achieves a data compression of 20 1 or greater Samples need only be recorded for data validation or if sample by sample eye position or velocity is required Events can record application data such as the time of a display change and experimental conditions or real time events such as button presses Events also define the start and end of blocks of data in the EDF file allowing applications to process data recorded with different data types Each event contains one or two timestamps in milliseconds and sev
129. me precautions should be observed Our experience has been that even safe levels of IR illumination can eventually cause some discomfort due to the slight drying effect of even this low level of illumination This is especially true for wearers of contact lenses SR Research recommends that the illuminators not be used for extended periods at distances of less than 150mm 6 inches from the eyes This will ensure an exposure of less than 1 2 mW cm milliwatts per square centimeter Exposure decreases as the square of the distance so even slightly larger distances will reduce exposure significantly In addition to its invisible light output the illuminators and heatsinks may become warm during operation Therefore the illuminators should be mounted so as to minimize unnecessary skin contact If illuminator mounting hardware is provided be sure to follow the assembly instructions as these may affect illuminator temperature Ensure the illuminators are mounted so that air flow is not excessively restricted as this could also increase the temperature Mounting the illuminator so that it is clamped directly to a large piece of metal will also help reduce its temperature The 910 nm infrared light from the illuminators is invisible under most viewing conditions A faint red glow may be visible in a dark room usually only after allowing 5 minutes your eyes to become dark adapted NOTE DO NOT position your eye closer than 100 mm 4 inches from th
130. ment Layout and Section 8 4 Customizing Your PHYSICAL INI Settings of the EyeLink 1000 Installation Guide document A summary of the setup procedure can be found at the end of the discussion 3 13 EyeLink 1000 Setup Summary This section leads you through a straightforward subject setup and pupil corneal reflection eye tracking demonstration For the easiest setup you should select a subject for the test that can sit still when required and does not have eyeglasses Once comfortable on these subjects you can tackle more difficult setup problems During the session description we take the opportunity to discuss many important aspects of system use These may make the setup appear long but a practiced experimenter can set up a subject in less than five minutes including calibration and validation If the EyeLink host software is not yet running on the Host PC start it by typing T H or alternatively CD CS ELCL EXE a EC al IMPORTANT Remember to exit the EyeLink software by pressing the key combination CTRL ALT Q Avoid switching off the computer while running the EyeLink 1000 software as data may be lost Now start a simple example application on the Display PC by selecting Start gt All Programs SR Research gt EyeLink gt TRACK EXE When TRACK starts a copyright message will appear on the Display PC and the status message at the top right should read TCP IP Link Open on the Host PC A
131. ment data can then be viewed with EyeLink Data Viewer with saccades and blinks overlaid to confirm the parsing accuracy Once correct parameters are determined they can be set by the EyeLink 1000 commands over the link as part of the experimental setup or the EyeLink 1000 configuration file PARSER INI REMPARSE INI for the EyeLink Remote or FINAL INI can be edited to change the default parameters 4 3 4 Parser Data Type Three eye position data types are available from the EyeLink 1000 tracker for each sample raw pupil position head referenced angle and gaze position see the section 4 4 File Data Types for more information The parser can use any one of these for detecting saccades and generating data for events The parser data type is set by the EyeLink command recording parse type It can be changed by editing the configuration file DEFAULTS INI or by sending a command over the link The text of the command is one of recording parse type GAZE recording parse type HREF recording parse type PUPIL 4 3 5 Saccadic Thresholds Three thresholds are used for saccade detection motion velocity and acceleration The values of these are in degrees degrees sec and degrees sec respectively The velocity threshold is the eye movement velocity that must be exceeded for a saccade to be detected A velocity threshold of 22 degrees per second allows detection of saccades as small as 0 3 ideal for smooth pursuit and psychophy
132. mmand is followed by a list of data types and options selected from the list below Keyword Effect LEFT RIGHT Sets the intended tracking eye usually include both LEFT and RIGHT FIXATION includes fixation start and end events FIXUPDATE includes fixation pursuit state update events SACCADE includes saccade start and end events Data Files 2005 2009 SR Research Ltd BLINK includes blink start and end events MESSAGE includes messages ALWAYS use BUTTON includes button 1 8 press or release events INPUT includes changes in input port lines not yet supported These examples of the command are the default event set and a fixation only configuration file event filter LEFT RIGHT FIXATION SACCADE BLINK MESSAGE BUTTON file event filter LEFT RIGHT FIXATION BLINK MESSAGE BUTTON 4 7 EDF File Utilities A number of utility programs are included in the EyeLink 1000 package to process and view EDF files The utility EDF2ASC translates EDF files into text ASC files for processing with user applications The EyeLink Data Viewer an optional tool allows displaying filtering and reporting output of EyeLink Data Files Please check EyeLink Data Viewer User s Manual for details 4 8 Using ASC Files The EDF file format is an efficient storage format for eye movement data but is relatively complex to support To make the data in EDF files accessible the translator EDF2ASC converts the files into a text version that is easily a
133. model is the only method available with the EyeLink Remote option Keyboard Shortcuts Q toggle selected pupil shape model Toggle display of pupil and CR crosshairs in camera images Keyboard Shortcuts X toggle crosshair display on off Threshold Coloring Toggle display of threshold coloring in camera images The coloring can be configured and is currently turquoise for the CR threshold yellow in earlier versions and blue for pupil thresholds Keyboard Shortcuts T toggle ring in display I Display PC l Image gt Display PC Select to present the camera display image on the Display PC monitor Keyboard Shortcuts ENTER toggle sending images over link Use Search Limits Indicates whether or not to use Search Limits see Set Options for a more comprehensive description Keyboard Shortcuts U Toggle search limit box on or off Mouse Autothresh If selected clicking on the pupil in the global image Host or Display PC tracks the pupil image at the clicked location and performs an automatic threshold computation Keyboard Shortcuts M Toggle Mouse click Autothreshold on or off Align Eye Window If the eye is tracked pressing the Align Eye Window button will center the search limits box on the pupil position EyeLink Remote only Keyboard Shortcuts A align the search limit box around eye position EyeLink 1000 Host Application 2005 2009 SR Research Ltd 2 These two buttons lo
134. modes that best suit their particular experimental paradigm or to accommodate different participant populations The cameras can be configured in a Tower Mount that allows highly accurate monocular recording with a wide field of view at up to 2000 Hz with the EyeLink 2000 Hz camera upgrade when the participant s head is supported by a chin and forehead rest In addition the camera can be affixed to a Desktop Mount attached to the mount at either a Level or Angled orientation that provides highly accurate monocular data acquisition using a chinrest Binocular gaze recording at up to 1000 Hz each eye is available with head stabilization when a 2000 Hz enabled camera is attached to the Desktop Mount in an Angled fashion A third mounting option is the LCD Arm Mount that affixes the EyeLink 1000 beneath an LCD monitor on a flexible arm so that the entire eye tracking apparatus and display can be easily moved into place in front of the viewer whose eyes are to be tracked The Long Range Mount with the Fiber Optic Camera can be used at up to 150 cm from the eye for electromagnetic sensitive environments e g EEG or MEG or environments where metal content needs to be minimized e g MEG or MRI Finally the Primate mount provides a mounting option for the camera so that Introduction 2005 2009 SR Research Ltd placement can be out of the way and above the subject making it ideal for use in animal recording situations The Desktop and LCD Arm M
135. mouse cursor on top of the pupil position and double click on the left mouse button The camera image for the eye should now be displayed in the zoomed view If the pupil is detected a green box and the cross now will be drawn on the eye image If the image becomes too dark or too light wait one second while the auto contrast adjusts itself If the blue thresholded area in the display is interfering with setup press the Threshold Coloring button or T on the keyboard to remove the threshold color overlay In TRACK EXE you can use keys on either the Display or Host PC to perform all keyboard shortcut operations while the eye image is displayed The camera should be focused by rotating the focusing arm slowly Look closely at the eye image on the zoomed view while adjusting the position of the focusing arm until the eye image is clear If a turquoise or yellow circle CR signal appears near the pupil the best focus will minimize the size this colored circle Now proceed to section 3 3 Setting Pupil Threshold Focusing Arm Poor Focus Good Focus Figure 3 4 Focusing the Eye Camera for EyeLink 1000 Tower Mount 3 2 2 Using the LCD Arm Mount Positioning the Apparatus The EyeLink 1000 LCD Arm Mount works in conjunction with highly accurate monocular recording with the head stabilized or with head free recording in the Remote mode licensing required Regardless of the recording mode positioning the Arm requires simil
136. n Figure 2 12 Gain Offset Adjustment in the Plot View 2 4 Status Panel The Status Panel allows users to monitor the status of the camera image of the tracked eye throughout the setup calibration validation and recording phases of every experiment A visual indicator illustrated in the figure below is present on the right hand side of the Calibrate Validate Drift Correct Output and Record screens and gives the operator a complete and continuous status report of the camera image For the EyeLink Remote status of target tracking is also provided PUPIL s RS CORHERL OK TARGET OK MISSING EYTEDIST Figure 2 13 EyeLink 1000 Status Panel For both the Pupil and Corneal Reflection status reports the left Status Panel column corresponds to the left eye and the right column corresponds to the right eye the status column representing the eye not being used is disabled The Status Panel indicators are summarized as follows Pupil OK green Pupil present and can be tracked at selected sample rate SIZE yellow Occurs when the pupil size is larger than the maximum allowed pupil size MISSING red Pupil not present Corneal only operational in Pupil CR mode OK green Corneal reflection is present and can be tracked MISSING red Corneal reflection is not present EyeLink 1000 Host Application 2005 2009 SR Research Ltd Target only available in EyeLink Remote OK green Target is present and can be tracked
137. n in several stages with R being the voltage range proportion and S being the proportion of screen width or height R voltage minvoltage maxvoltage minvoltage S R maxrange minrange minrange Xgaze S screenright screenleft 1 screenleft Ygaze S screenbottom screentop 1 screentop 7 5 Pupil Size Data For pupil size either pupil area or pupil diameter may be monitored These are very high resolution measurements with resolution as small as 5 microns 0 005 mm Pupil size measurements are affected by eye position due to the optics of the eye and camera and should be considered to be measured in arbitrary units with a pupil size of zero being represented by the lowest analog voltage 7 6 Timebase and Data Strobe The EyeLink 1000 eye tracker samples eye position every 0 5 1 2 or 4 ms and outputs analog data at 2000 1000 500 or 250 hz depending on your tracker setting and system licensing This combination of fast sampling rate and non continuous output differs from most eye tracking systems with analog outputs which either output continuous analog data such as limbus tracking systems or output samples at a lower rate such as 50 60 Hz video based tracking systems This causes the EyeLink analog output to rapidly step between data values which means that sampling at fixed intervals makes it likely that samples might be missed sampled twice or the transition between samples might be recorded instead Since t
138. n via the use of a small target sticker placed on the participant s forehead If your system is licensed to use the EyeLink Remote mode take the following steps to set up the camera and perform image adjustments 1 For the EyeLink Remote affix the 16 mm lens shipped standard with a short adjustable focus arm or small wheel to the high speed camera 2 Desktop Mount users should check that the camera is in the level position the elongation of the camera should be parallel to the table and the upper surface of the camera will align smoothly with the top of the mount with the Camera Screw in the topmost position If the camera is not in this position loosen the Camera Screw at the front of the Desktop Mount and move it to the top end of the slot Hold the camera with its elongation parallel to the table and its top surface flush with the mount and tighten the screw Dimples on the camera fit into projections on the mount to ensure that the camera is in the proper position Plug in the illuminator cables and the power cable into the camera Also make sure the camera data cable coming from the Host PC the end with a right angle connector has been connected to the back of the camera and tightly fastened with the thumb screws 3 In addition to an active license programmed in the hardware the EyeLink Remote requires version 4 0 or later of the EyeLink 1000 host software which can be downloaded from the SR Research Support website https
139. nally received the system in Store the shipping case above freezing and below 40 C and avoid high humidity conditions which might cause water to condense within the Tower and damage the optics Be sure to follow the unpacking and installation instructions when returning the packaged unit to operation see the EyeLink 1000 Installation Guide If the EyeLink 1000 card is also to be packaged remove it from the computer and place it into its anti static bag then into its slot in the foam oystem Care 2005 2009 SR Research Ltd 6 Important Information 6 1 Safety 6 1 1 Eye Illumination Safety WARNING Illuminators must only be connected to EyeLink 1000 camera and only the supplied cables may be used CAUTION Use of a controls or adjustments or performance of procedures other than those specified herein may result in hazardous radiation exposure CLASS 1 LED DEVICE IEC 60825 1 Ed 1 2 2001 The EyeLink 1000 illuminators are compliant with the IEC 60825 1 LED safety standard as a Class 1 LED device This standard has been or is in the process of being adopted by most countries and regulates many aspects of LED and laser eye safety including retinal corneal and skin safety Class 1 products are safe under reasonably foreseeable conditions of operation including the use of optical instruments for intrabeam viewing As these illuminators may be used in situations where they may be viewed for long periods of time so
140. nctions Click to go to the Camera Setup screen Camera Setup Keyboard Shortcuts ENTER Camera Setup Click to see Help and keyboard shortcuts Help F1 Keyboard Shortcuts F1 Help screen Terminate Calibration sequence Keyboard Shortcuts ESC Abort ET Restart the Calibration Auto Trigger Click to automate the calibration sequence according to the Pacing Interval from the Set Options screen Keyboard Shortcuts A Auto Trigger Accept Press to accept fixation value after the participant s gaze is stable on the target Keyboard Shortcuts ENTER Spacebar Accept Fixation Calibrate Screen Key Shortcuts Key Function A Auto calibration set to the pacing selected in Set Options GEN menu Auto trigger ON EyeLink accepts current fixation if it is stable During Calibration ENTER or Spacebar Begins calibration sequence or accepts calibration value given After first point also selects manual calibration mode Terminates calibration sequence ibrati Manual calibration Auto trigger turned off Auto calibration set to the pacing selected in Set Options menu Auto trigger ON EyeLink accepts current fixation if it is stable Repeats previous calibration target After Calibration gt Z O EyeLink 1000 Host Application 2005 2009 SR Research Ltd 2 3 5 Validate Screen Validate TCF IF Link Open Tracking Right Eye Pup
141. ne skip or or Comment line skip i Preamble line skip Digit 0 9 sample line Letter A Z Event or Specification line Once the line is identified it may be processed Some lines may simply be skipped and the next line read immediately For sample lines the tokens in the line can be read and converted into numerical values The token represents a missing value and may require special processing For lines where the first token begins with a letter processing depends on what the first token is The tokens after the first are read and desired data from the line are extracted from them Lines with unrecognized first tokens or with unwanted information can simply be skipped Processing of events and samples will depend on what type of analysis is to be performed For many cognitive eye movement analyses MSG line text specifying experimental conditions EFIX event data and BUTTON event times from each block are used to create data files for statistical analysis For neurological research samples between SFIX and EFIX events can be processed to determine smooth pursuit accuracy and gain In some cases an entire block of samples may need to be read and stored in data arrays for more complex processing For all of these the organization and contents of the ASC files have been designed to simplify the programmer s task Data Files 2005 2009 SR Research Ltd 5 System Care 5 1 Maintenance The EyeLink 1000 system sho
142. not required Digital outputs may be set by the write ioport command which may be issued though the link or by a button or initialization file command The port address for the C and D ports on the EyeLink analog output card are 4 and 5 respectively Digital outputs may also be reserved for EyeLink tracker functions and writing to these bits has no effect For example when analog output is enabled the data output D7 is used as a strobe output to indicate when new analog data is available The digital inputs may be used as buttons and as input port bits which may be recorded in the EDF data file or sent as samples via the Ethernet link Button inputs may be connected to a digital output such as a printer port from a control computer and assigned functions such as starting and stopping recording or used as synchronizing marks in the data file When used as a real button for participant response the button is typically connected to ground a 10 K ohm resistor should be connected from the input to one of the 5V Appendix A Using the EyeLink 1000 Analog and Digital Output Card 2005 2009 SR Research Ltd terminals on the connection board Buttons and input ports are defined in BUTTONS INI with port addresses of 2 for port A and 3 for port B Here is an example of defining a button on port A and assigning port B as the input port create button 8 2 0x01 1 button 8 input AO O0 is active Input data ports 3 77 digital inputs BU
143. ns uto Threshold Click to have the Host PC compute threshold levels automatically Fine tuning may be necessary The EyeLink Remote dynamically adjusts threshold levels that are further biased by threshold adjustments Keyboard Shortcuts A Auto Threshold selected image Clicking these buttons manually increases or decreases the selected pupil threshold or pupil threshold biases for the EyeLink Remote Keyboard Shortcuts ff and U increase and decrease pupil threshold bias Biers In Pupil CR mode these buttons manually increase or decrease the selected CR threshold or CR bias for the EyeLink Remote Keyboard Shortcuts and increase and decrease CR threshold bias Pupil CR Select the tracking mode for recording Typically with most shipped systems Pupil CR is the only mode available as Pupil alone tracking requires complete head immobilization for high accuracy Keyboard Shortcuts P toggle Pupil only or Pupil CR mode where possible EyeLink 1000 Host Application 2005 2009 SR Research Ltd sample Rate Select the sampling rate for recording Here 1000 1K Hz is selected The 2000 Hz rate is available only with the EyeLink 2000 camera upgrade Keyboard Shortcuts F alternates Sample Rate selection Pupil Tracking Select the method used to fit the pupil and Centroia determine pupil position Measures of Area or Diameter are always based on the Centroid Model An Ellipse
144. ongation of the camera should be parallel to the top of the mount see the figure below If not please loosen the Camera Screw and move it to the top end of the slot Hold the camera with its elongation parallel and level with the top of the mount and tighten the screw 3 The camera and illuminator should be placed at a distance of 40 to 70 cm from the observer measured from the front end of the Camera Screw to the rear distal end of the chinrest pad The ideal tracking distance is from about 50 to 55 cm 4 If using the Desktop Mount the Camera Screw should be roughly aligned to the center of the monitor You should also raise the Desktop Mount so that the top of the illuminator is as close as possible to the lower edge of the visible part of the monitor for maximum eye tracking range 9 Start the EyeLink Host PC application and click Set Options button Check that the Configuration is set to Desktop Level amerre Screw Ilurninator Cable H a igh epeed Camera peed Camera Lock Knob Figure 3 5 Parts of the EyeLink 1000 Desktop Mount 6 Ensure the lens cap has been removed from the camera by pulling the cap outwards while holding the camera An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd 7 If you are using the chinrest supplied by the SR Research Ltd please install the forehead rest to the chinrest if you haven t done so yet Ask the subject to be seated Adjust the
145. ons or the and keys to manually adjust the CR threshold c Have the subject slowly look along the edges of the display surface and ensure that the corneal reflection does not get lost If the CR does get lost a red warning message will appear below the small camera image for the eye indicating No CR on the Host PC NOTE The corneal reflection may not be stable with all subjects particularly those wearing glasses with a heavy anti reflection coating when using the Tower Mount If after ensuring the Tower Mount IR mirror Desktop Mount optics is positioned correctly subject properly seated and thresholding has been performed you are unable to acquire a stable corneal reflection it is suggested that you do not use the subject for the experiment Unlike the EyeLink II don t attempt to switch to pupil only mode for tracking of the subject without using a bite bar An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd 3 5 Search Limits The EyeLink 1000 eye tracker also provides a Use Search Limits option If enabled it draws a red box or ellipse in the global view of the camera image and reduces the area of the full camera image that is searched to find the eye If the subject does not wear glasses you may uncheck the Use search limits button on the Camera Setup screen This allows the tracker to search for pupil position across the whole camera image in case the pupil position is lost The
146. or pupil size during fixations usually requires processing all samples produced by the tracker This is acceptable for file data but is expensive for real time systems using data sent via the link Fixation updates solve this problem by sending updates on eye position pupil size Data Files 2005 2009 SR Research Ltd velocity etc at regular intervals during a fixation The first update is sent one update interval after the start of the fixation and the last is sent at the end of the fixation Data is aggregated over a preset period which lowers data noise The interval between updates and the data accumulation period can both be set Fixation updates are most useful for real time display paradigms In some studies the subject is required to fixate a target while stimuli are presented Fixation updates can be used to check gaze position every 100 msec or so Computer interfaces operated via eye movements is a paradigm dramatically simplified by fixation updates Actions are triggered by gaze on an active area of the screen for a critical duration This is implemented simply by counting sequential fixation updates that fall within the area Two commands set the fixation update interval and data accumulation period in milliseconds Usually these are set to the same value An interval of zero disables fixation update An update interval of 50 or 100 msec is a good choice fixation update interval 100 fixation update accumulate 100
147. ortcuts ESC Previous Screen Tia fan Click to view Camera Setup screen Keyboard Shortcuts ENTER Camera Setup Click to access the online help page for Set Options Help F1 screen Keyboard shortcuts are listed on the Help screen Keyboard Shortcuts F1 open Help screen Settings Clicking Revert to Last restores EyeLink settings to the values active at the beginning of the current session which were also the settings active at the Load Defaults end of the last session Clicking Load Defaults reverts to settings specified in the DEFAULTS INI file Keyboard Shortcuts L Revert to Last configuration D Load Defaults EyeLink 1000 Host Application 2005 2009 SR Research Ltd Clicking Video Setup goes to the Video Setup screen Video Overlay Video Setup Clicking Enable Overlay activates the video overlay Enable Overlay option Keyboard Shortcuts V toggle video setup O toggle video overlay on off Recording Data View These settings control what to Record View Plotting show on the Record screen during data output If Record Jd Gaze View is set to Gaze Cursor the Host PC Record screen will display the participant s current gaze position as a cursor graphic overlaid on a simulated display screen If set to Plotting x y data traces will be graphed as a function of time The user can further select which data type should be plotted See Section 2 3 8 Keyboard S
148. ote operates at much higher acquisition rates 500 Hz translating into fewer missed data points all with no moving parts to interfere with stimulus delivery and invalidate the experimental setting A typical EyeLink setup is depicted in Figure 1 1 This figure illustrates the Tower Mount The system consists of two computers one the Host PC is dedicated to data collection The second PC is referred to as the Display PC and is generally used for the presentation of stimuli to a participant The two computers are connected via an Ethernet link that allows the sharing of critical information from the Host PC to the Display PC such as the occurrence of eye Introduction 2005 2009 SR Research Ltd events or images from the camera Similarly the Display PC can communicate with the Host PC allowing Display PC applications to direct the collection of data An EyeLink button box is attached directly to the Host PC allowing for the accurate synchronization of participant responses with the eye movement data Message passing also allows events collected by I O devices on the Display PC e g button boxes microphones etc to be accurately noted in the data file IMPORTANT Please examine the safety information for the EyeLink 1000 system found in Section 6 1 1 1 Supporting Documents The EyeLink 1000 User Guide this document contains information on using the EyeLink 1000 hardware the Host PC application tutorials on subject setu
149. ounts can be used in a highly flexible Remote Mode with the Remote Camera option to record gaze position at 500 Hz monocularly without head stabilization Combined with the LCD Arm Mount Remote Mode is ideal for reaching viewers in difficult to record positions as it brings the eye tracker and display to the subject instead of making the viewer conform to the setup required by the eye tracker The fact that Remote recording operates without head stabilization further increases the system s flexibility S Video Out Gaze Video Overlay Optional EyeLink M Mor amp Host Computer Display Keyboard Analog Outputs Computer Analog Digital Optional v Card optional ial xperimen op Digital Inputs PEE EyeLink Ethernet EyeLink API Card Library Display Response Box EyeLink 1000 Figure 1 1 Typical EyeLink 1000 Configuration Tower Mount All configurations of the EyeLink 1000 operate at the unparalleled low variability required for accurate gaze contingent paradigms and the highly accurate and sensitive operation that careful research demands EyeLink systems are the only modern equipment to run on a real time operating system for low variability and near instant access to eye data measures Although Remote recording understandably has more noise than recording with the head stabilized it nevertheless continues to be highly accurate though of lower resolution Compared to other remote systems on the market the EyeLink Rem
150. ous velocity in degrees per second compute the x and y velocities then divide each by the x or y resolution square and add the x and y velocities and take the square root Resolution is computed at the point of gaze on the display and can vary up to 15 over the display The resolution data in an EDF file is recorded using a prescaler for extra precision and noted in the gaze position section 4 4 3 Pupil Size Data Pupil size is also measured by the EyeLink 1000 system at up to 2000 samples per second depending on your tracker version It may be reported as pupil area or pupil diameter The pupil size data is not calibrated and the units of pupil measurement will vary with subject setup Pupil size is an integer number in arbitrary units Typical pupil area is 100 to 10000 units with a precision of 1 unit while pupil diameter is in the range of 400 16000 units Both measurements are noise limited with noise levels of 0 296 of the diameter This corresponds to a resolution of 0 01 mm for a 5 mm pupil Pupil size measurements are affected by up to 1096 by pupil position due to the optical distortion of the cornea of the eye and camera related factors If research using pupil size is to be performed the subject should not move their eyes during the trials They can be presented with a fixation point with aural stimulus presentation or a single stimulus position at display center may be used It is also possible to counterbalance stimu
151. ovement condition and another at the end of the condition When used in real time processing with data set via the link the event pairs allow an application to monitor eye movement state in real time These pairs accurately label the samples in a file between the events as the file is read from beginning to end Eye movement events are always labeled by which eye generated the event If binocular data is recorded a separate start and end event is generated for each eye The time differences between eyes are very important for neurological analysis for example The main classes of data events are summarized below Start events contain the time of the start of the eye movement condition They may also contain the state of the eye at the onset of the condition for example the position and pupil size at the start of a fixation End events contain both the start and end time of the condition The end time is actually the time of the last sample in the condition so length of a condition must be computed as the difference between the end and start times plus the time between samples 1 2 or 4 milliseconds End events also contain summary data on the condition as well average gaze position of a fixation for example 4 5 3 1 Record Blocks Each block of recorded data in an EDF file begins with one or both of a STARTSAMPLES or STARTEVENTS event These contain the time of the recording start and specify what data can be expected to follow This
152. p and calibration and the basics of running an experiment Information on system safety maintenance and storage is also provided Appendix A of this manual explains the use of the optional analog output and digital inputs and outputs via a DT334 card Additional documents are also available A EyeLink 1000 Installation Guide Describes a standard EyeLink 1000 system layout and environmental considerations as well as the process followed to install the EyeLink 1000 hardware and software on both the Host and Display PCs B EyeLink Programmer s Guide Provides suggestions on how to program experiments with EyeLink 1000 in Windows including review of sample experiments provided and documentation of supported functions C SR Research Experiment Builder User Manual Introduces an optional visual experiment creation tool for creating EyeLink experiments on Windows 32 bit operating systems This software allows for a wide range of sophisticated experimental paradigms to be created by someone with little programming or scripting expertise D EyeLink Data Viewer User s Manual Introduces an optional Data analysis tool EyeLink Data Viewer which allows interactive display filtering extraction and summarizing of EyeLink EDF data NOTE Please be sure to check http www sr support com for product and documentation updates as they become available Introduction 2005 2009 SR Research Ltd 1 2 EyeLink 1000 System Configuration 1 2 1
153. portant Information 2005 2009 SR Research Ltd of the illuminator to be adjusted it may be necessary to adjust the angle of the illuminator to provide the best illumination of the object of interest 6 2 3 Cables and Lenses The following components are replaceable if the substitutions are made with components supplied by or approved by SR Research Ltd 6 2 3 1 Camera Lenses Almost any C mount lens may be used in the visible spectrum The high resolution sensor in the EyeLink 1000 camera performs best with high resolution machine vision lenses and noticeable blurring may be seen at the edges of the image with standard CCTV optics Please contact SR Research if a CS mount lens is required for your application The EyeLink 1000 camera is optimized for near infrared to 910 nm use however performance in this range depends critically on proper lens selection The majority of C mount lenses perform poorly beyond 800 nm with blurry images especially zoom lenses or dark images due to loss from optical coatings Please contact SR Research for a current list of lenses we have approved for IR use 6 2 3 2 Cables The illuminator cables should not be replaced with other cables without the express permission of SR Research The ferrites on the cable must remain in place and be positioned within 10 cm 4 of the camera The Camera cable from the computer to the camera may be replaced with any compatible cable up to 10 meters in l
154. r can do Post processing or data cleanup may be needed to prepare data during analysis For example short fixations may need to be discarded or merges with adjacent fixations or artifacts around blinks may have to be eliminated Nonetheless the EyeLink 1000 parser does an excellent job in most recording situations Adjusting the configuration of the parser may help bias its performance for specific applications such as smooth pursuit or reading research Its performance is easily checked record eye movements using the display of interest with both sample and event data Then view the EDF file with EyeLink Data Viewer or convert the EDF file to an ASC file to see the correspondence between eye movements and the parser output 4 3 3 EyeLink Parser Configuration The saccadic detection parameters for the EyeLink 1000 on line parser may need to be optimized for the type of experimental investigation being performed For example neuropsychophysical researchers may need to detect small saccades amid pursuit or nystagmus while reading researchers will need to detect only large saccades and will want fixation durations maximized This Data Files 2005 2009 SR Research Ltd section explains the function of and suggests values for the most useful parser parameters Some experimentation may be required to select the best parameters The user can try different parser settings and perform recordings with full sample data recorded The eye move
155. r on top of the pupil position and double click on the left mouse button The camera image for the eye An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd should now be displayed in the zoomed view If the pupil is detected a green box and the cross will be drawn on the pupil This step can also be performed from the Display PC using its mouse by clicking on the pupil in the global image 3 Use the left or right cursor key to select the zoomed camera view Adjust the camera focusing by turning the focusing ring on the lens Performing the adjustments from the side of the mount with the lens will prevent the illumination or the camera s view from being blocked Look closely at the eye image on the zoomed view while turning the focusing ring until the eye image is clear If a turquoise circle CR signal appears near the pupil the best focus will minimize the size of this turquoise circle see Figure 3 7 3 2 7 2 Binocular Long Range Subject Setup Binocular recording is essentially the same as the monocular recording described above except that the Configuration in the Set Options screen should be set to Long Range Mount Binoc Monoc and the Camera Head orientation should be angled In the global camera view the eyes should appear in the center of the camera image with the dotted line aligned with the bridge of the nose For more information about recording in binocular mode see Section 3 2 6 3 2
156. r with these reversed Your Host PC should have the software configured for your mount Other entries in the descriptor include the recommended lens to use and reminders about conditions of recording e g Stablized Head Target Sticker Monocular Remote recording modes require licensing of the EyeLink Remote software option Configurations with the camera angled can record monocularly or binocularly Configurations with the camera level are monocular Each recording mode includes a description with the recommended lens SET CONFIGURATION Monocular 35mm stabilized Head Camera Level Ch HM MTABLER Binoc HMonoc 3 25mm stabilized Head Camera Angled CAM BTABLER Monocu lar 16mm Target Sticker Camera Level CAM RTABLER Monocular 16mm Target Sticker ARTABLER Monocular 35mm Stabilized Head ANTABLER Clicking on the Select Config button raises the dialog box above from which other modes of data collection can be selected Each column consists of the description entries and the last entry is a unique identifier for the configuration that will be logged in the EDF file For the Tower Primate and Long Range mounts the available configurations are shown below Binocular recordings are supported in the Primate and Long Range mounts SET CONFIGURATION Monocular j5 75mm lenses Stabilized Head Camera Level Binoc Monoc 35 5mm lenses Stabilized Head Camera Angled Monocular eomm lens stabilized Head Monocular eomm l
157. rch area moves relative to the pupil Search Limits are automatically active with the EyeLink Remote as the entire image is searched on every frame given that head movement is not restricted In Mouse Simulation mode the Host PC mouse simulates eye movements and can be used for experiment testing and debugging purposes Keyboard Shortcuts M toggle on off Mouse Simulation F4 toggle Search Limit on off F5 toggle dynamic updating of the Search Limit area around the pupil Pupil Size Data AREA Record the pupil area or diameter in pixels The area is recorded in scaled image pixels Diameter is calculated from pupil area fit using a circle model Keyboard Shortcuts S alternates between pupil Area or Diameter data EyeLink 1000 Host Application 2005 2009 SR Research Ltd Select whether to record eye events Eye Event Data Gaze HREF fixations and saccades in Gaze or HREF coordinate GAZE is screen gaze x y HREF is head referenced calibrated x y Keyboard Shortcuts E alternates between Gaze and HREF settings re eC Defines the sensitivity of the ests thei NORMAL MEET Sal id 1060 convene hee Aapnide event generation Normal is intended for cognitive tasks like reading while High is intended for psychophysical tasks where small saccades must be detected See Section 4 3 5 Saccadic Thresholds for details of event parsing Keyboard Shortcuts X alternates between Saccade Sensitivity levels Selec
158. reeereessssesreeeessses 32 Figure 2 9 EyeLink 1000 Output Screen ceeeeseeeeeeeeeeeee eene nennen nennen 34 Figure 2 10 Record Screen Gaze Cursor View cccceceeceeeceeeeeeeeeeeeeseeeeenes 35 Figure 2 11 Record Screen Plot View ccce ccc ece cece eee eeeeeeeneeeeseeeeenseeeenes 36 Figure 2 12 Gain Offset Adjustment in the Plot View cccc ccc ceeeeneeeeeees 41 Figure 2 13 EyeLink 1000 Status Panel debet eto ied aor h en abide dump eai begun ts 41 Figure 3 1 Example Camera Setup Screen Desktop Mount 46 Figure 3 2 Parts of the EyeLink 1000 Tower Mount esee 48 Figure 3 3 Adjust the Chair Height for EyeLink 1000 Tower Mount 49 Figure 3 4 Focusing the Eye Camera for EyeLink 1000 Tower Mount 50 Figure 3 5 Parts of the EyeLink 1000 Desktop Mount sssssssssssssssssresesssses 52 Figure 3 6 Camera Setup with Subjects Wearing Glasses the EyeLink 1000 Monocular MOE seier aa E A E E E E E 54 Figure 3 7 Focusing the Desktop Mount Camera eese o4 Figure 3 8 Camera Setup Screen with the EyeLink Remote 56 Figure 3 9 EyeLink Remote Target Placement s ssessssssssereeesrssesesreeeeessees o8 Figure 3 10 Pupil and CR Thresholds and Bias Values 59 Figure 3 11 Status Panel Pupil Size Information eene 61 Figure 3 12 Tar
159. ricted range of looking will be on the same side of space as the camera For example when tracking the left eye a greater range is available when the subject is looking to the right because when the subject looks far to the left the nose will occlude the camera s view of the left eye 8 For optimal performance adjust the subject s seating distance so that the tracker reports a target camera distance of about 550 mm to 600 mm in the zoomed target view bottom right camera image If subject is seated too close to the camera the Host PC will display a DIST CLOSE error If the subject is seated too far from the camera the tracker will report a DIST FAR error If the tracked eye does not appear centered in the global camera view the angle of the Desktop Mount may be rotated slightly An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd TARGET OK DIST OK MISSING I CORNEAL MISSING TARGET OK MISSING EYEDIST Target is too close to the eye vertically DIST OK Status Panel PUPIL K O SIZE MISSING CORNEAL OK j MISSING TARGET OE MISSING EYEDIST Target angle too steep to be recognized properly Status Panel MISSING SS CORNEAL HISSING TARGET OK MISSING ANGLE Figure 3 9 EyeLink Remote Target Placement 9 The camera image is now ready for fine tuning adjustments and establishing of threshold biases In the global view window of the camera image Host or Display PC
160. rsor on top of the pupil position and double click on the left mouse button The camera image for the selected eye should now be displayed in the zoomed view If the pupil is detected a green box and the cross now will be drawn on the eye image Please note that for most subjects you will just need to adjust the height of the chinrest and chair to get the intended camera image without changing the Desktop Mount settings However for subjects wearing glasses depending on the shape and reflection of the glasses you may need to make slight adjustments to the Desktop Mount e g moving the camera closer to the subject lowering the position of the camera and adjusting the angle of the illuminator and camera so that reflections from the glass will not interfere with pupil acquisition The left panel of the following figure illustrates a good camera An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd setup whereas the reflections in the right panel block the pupil image especially when the subject looks in the direction of the glass reflection P E 4 Pupil 69 Pupil 69 CR 229 CR MEAS PUPIL OK NO PUPIL CR OK NO CR Figure 3 15 Camera Setup with Subjects Wearing Glasses Desktop Mount Camera Angled If the image becomes too dark or too light wait one second while the auto contrast adjusts itself If the blue thresholded area in the display is interfering with setup press the Threshold Coloring
161. s Gaze Angle or HREF Keyboard Shortcuts ALT f U Adjust zooming levels Sets the gain value when used with mouse or ALT f and ALT U keys These buttons will only be available when the plotting data is RAW or Analog Keyboard Shortcuts ALT f1 U Adjust gain values Scrolls the eye traces up or down or use CTRL ff and CTRL keys These buttons will only be available when the plotting data type is Gaze Angle or HREF Keyboard Shortcuts CTRL f1 l Control scrolling Selects offsets when used with mouse or CTRL and CTRL lU keys These buttons will only be available when the plotting data is set to RAW or Analog Keyboard Shortcuts CTRL f1 U Adjust offset values Undo the last view or gain offset change Keyboard Shortcuts U Undo last view or gain offset change Change to the default view or gain offset Keyboard Shortcuts D Revert to default view Fit all data to view auto gain offset adjusting Keyboard Shortcuts Tab Fit all data to view EyeLink 1000 Host Application 2005 2009 SR Research Ltd Load the Analog or raw gain and offset settings from a saved oa PRE file Save Analog or raw Gain and Offset settings into a none gt PRE file Keyboard Shortcuts L Load analog or raw gain offset Save on settings S Save analog or raw gain offset settings 2 3 8 4 Record Screen Key Shortcuts Toggle between Gaze Cursor and Plot Views Video Overlay Only R
162. s a gaze contingent display where the part of the display the subject is looking at is changed or where the entire display is modified depending on the location of gaze These require high sampling rates and low delay which the EyeLink 1000 tracker can deliver through the link An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd This template demonstrates how to use the link s real time gaze position data to display a gaze contingent window This is an area centered on the point of gaze that shows a foreground image while areas outside the window show the background image You supply full screen sized bitmaps for these which are stored in the bmp folder You can use different images by replacing the one provided with the experiment with an image of your own with the same name F Control This template implements a computer interface that is controlled by the subject s gaze The participant can select one of a grid of letters by fixating on it The template contains code to support many rectangular selection regions but can be simplified if gaze in a single region is all that needs to be detected The image for the trial is a grid of letters G Dynamic This template consists of four experiment blocks In the first block a red horizontal moving dot is presented which moves from left to right then back again repeatedly The second block presents a red which moves right to left then changes to V when moving
163. s and events in the block and allow flexible data processing without prescanning the file e All eye movement samples and events occur between the START event and the matching END event e All events and samples appear in temporal order That is the timestamps of samples end time timestamps of eye movement end events and start time timestamps of all other events will be the same or greater than any preceding data e Eye data samples are nested between eye movement start and end event For example the first sample in a fixation will follow the SFIX event for that fixation and the EFIX event for a fixation will follow the last sample in the fixation This allows on the fly classification of samples as the data file is read Before writing an analysis program to process an ASC file it is helpful to convert a small EDF file containing the data of interest and examine it with a word processor or print it out 4 9 2 Sample Line Format Sample lines contain time position and pupil size data Optionally velocity and resolution data may be included Several possible sample line formats are possible These are listed below Essentially each sample line begins with a timestamp Recordings done with a 2000 hz sampling rate will have two consecutive rows of the same time stamps The second row refers to the sample collected at O 5 ms after the reported time stamp The time stamp field is followed by X and Y position pairs and pupil size dat
164. s there are no user serviceable parts inside and no internal adjustments or jumpers Please contact SR Research for repair or replacement if you suspect these are at fault There are no user serviceable parts within any of these components 6 2 2 Illuminator Replacement Before replacing an illuminator unplug the power supply from mains power and or unplug the power cable from the camera Carefully note the routing of illuminator cables and the alignment of the illuminator if adjustable in order to restore these during reassembly Illuminators are attached to the camera by a short cable with plugs at each end and mounted by a large metal heat sink Do not attempt to disassemble an illuminator or remove it from its heat sink Instead the illuminator should be detached by removing clamps or screws or knobs holding it to its mounting If the illuminator cable is fastened to the illuminator s heat sink unplug the cable s from the camera otherwise you may unplug the cable from the illuminator itself Dismount the illuminator instructions for this procedure may be included in documentation for mounting systems Re mount the new illuminator instructions depend on the mount restore the routing of the illuminator cable s and reconnect the cable to the camera or illuminator Reconnect the power supply start the application software and check to be sure the illuminator is producing proper output If the mount allows the angle Im
165. screen Click on the Pause button to pause display sweeping Make sure that only the X Sel button is selected Click at the blank space next to the graph A green marker will appear at the selected value For the ease of adjustments you may set that point close to center of the left and right eye traces Also note that a white bar at the right end of the graph This bar sets the upper and lower bounds for gain and offset adjusts To adjust the gain of eye traces place the mouse cursor outside of the regions bounds by the white bar Drag the mouse up or down until the span of the upper and lower eye traces spans 8 volts You will notice that both the gain and offset values are updated when you drag the mouse up or down Now place the mouse cursor in the regions bounds by the white bar Drag the mouse up or down until the top of the eye trace is aligned with 4 volts and bottom of the eye trace is aligned with 4 volts Repeat steps 5 and 6 for fine tuning Once you are happy with the adjustments don t forget to unselect the SEL buttons on the Adjust button so that you will not accidentally touch the adjustments Now your Calibration is done Click on the Pause button to continue recording EyeLink 1000 Host Application 2005 2009 SR Research Ltd Record Stop Record ny Record ing Threshald ra k ing J E n p ia H 2 Adjustment Phase Will e Test Phase tic Manual record ir Sess io
166. sical research A conservative threshold of 30 sec is better for reading and cognitive research shortening saccades and lengthening fixation durations The larger threshold also reduces the number of microsaccades detected decreasing the number of short fixations less than 100 msec in duration in the data Some short fixations 2 to 3 of total fixations can be expected and most researchers simply discard these Use of eye movement acceleration is important for detection of small saccades especially in smooth pursuit Acceleration data has much more noise than velocity data and thresholds of 4000 sec for small saccade detection and 8000 sec for reading and cognitive research are recommended Lower acceleration thresholds will produce false saccade reports Acceleration data and thresholds for the EyeLink 1000 system may be larger than those reported 88 Data Files 2005 2009 SR Research Ltd for analog eye trackers These systems use multi pole filters for noise reduction that adds delay and smoothes the data significantly reducing the measured acceleration The saccadic motion threshold is used to delay the onset of a saccade until the eye has moved significantly A threshold of 0 1 to 0 2 is sufficient for shortening saccades Larger values may be used with caution to eliminate short saccades for example a threshold of 0 4 will always merge fixations separated by 0 5 or less but may eliminate some 1 saccades as well
167. so setting the display to match the settings in PHYSICAL INI is not crucial For highly accurate monocular data collection however the distance between the LCD display and the viewer should match the distance specified in PHYSICAL INI as closely as possible Having a tape measure handy to check that Arm positioning is at the viewing distance specified in PHYSICAL INI is a good idea For instructions pertaining to the assembly disassembly and transport of the LCD Arm Mount see the EyeLink 1000 Installation Guide Now that the LCD Arm Mount is in place to continue the setup tutorial go to either Section 3 2 3 Desktop Mount Participant Setup Monocular or Section 3 2 4 EyeLink Remote Participant Setup if using the system without head stabilization Remote licensing required Keep in mind that most references to the Desktop Mount in these sections will not apply An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd 3 2 3 Desktop Mount Participant Setup Monocular The EyeLink Desktop Mount can be configured to track monocular eye movements up to 2000 Hz or binocular movements up to 1000 Hz depending on the system model Take the following steps if you plan to set up the EyeLink 1000 Desktop Mount for monocular tracking 1 First check whether the 35 mm lens without a focusing arm or ring has been installed 2 For the Desktop Mount check that the camera is set to the horizontal position the el
168. t exp gt lt eyp gt lt aps gt lt av gt lt pv gt lt ampl gt lt xr gt lt yr gt 4 9 3 3 Messages which eye caused event L or R timestamp in milliseconds timestamp of first sample in milliseconds timestamp of last sample in milliseconds duration in milliseconds average X and Y position start X and Y position data end X and Y position data average pupil size area or diameter average peak velocity degrees sec saccadic amplitude degrees X and Y resolution position units degree e MSG lt time gt lt message gt A message line contains the text of a time stamped message This will have been sent to the EyeLink 1000 tracker by an application and contains data for analysis or timestamps important events such as display changes or subject responses The lt message gt text fills the entire line after the timestamp and any blank space following it 4 9 3 4 Buttons e BUTTON lt time gt lt button gt lt state gt Button lines report a change in state of tracker buttons 1 through 8 The lt button gt reports which button has changed state The lt state gt value will be 1 if the button has been pressed O if it has been released Tracker buttons may be created to monitor any digital input port bit and may be created by link commands or in the tracker configuration file BUTTONS INI 4 9 3 5 Block Start amp End Data Files 2005 2009 SR Research Ltd e START time eye
169. t filter level of data Juss UE EXTRA recorded to the EDF file Each increase in filter level reduces noise by a factor of 2 to 3 Keyboard Shortcuts F2 alternates between filter levels for the EDF file Note Online Parsing and the EyeLink Data Viewer assume use of the File sample Filter SR Research Ltd recommends leaving this value set to EXTRA Select the filter level for data Link fmalog Filter STD available via the Ethernet link Each increase in filter level reduces noise by a factor of 2 to 3 but introduces a 1 sample delay to the link sample feed Keyboard Shortcuts F3 alternates between filter levels for the link Analog Output Select the type of data for analog I 1 output OFF turns off analog para Busi Gaze output RAW is pupil x y in camera coordinates HREF is head referenced calibrated x y GAZE is screen gaze x y Keyboard Shortcuts A alternates between analog output options EyeLink 1000 Host Application 2005 2009 SR Research Ltd Conf iguration select the tracker configuration Each configuration consists of the Camera Mount Type Tower Desktop LCD Arm Long Range Mount with the Camera Mode or Orientation Remote Level Angled in parentheses loli Additionally there are two types of Desktop Mount Stabilized Head one with the Illuminator on the Left and the Camera Canera Level on the Right ILLUM CAM selected in the Figure at CAM ILLUM left and the othe
170. the EyeLink button box B Text This experiment is an extension of the Simple experiment and uses a slightly more complex process for drawing to the Display PC monitor For more complex display such as screens of text or pictures drawing takes too long to complete in one or two display refreshes This makes the drawing process visible and there is no clear stimulus onset for reaction time measurement The code in the text template draws to a bitmap an image in computer memory not to the display then copies it to the Display PC monitor reducing the time to make the display visible This also has the advantage of making the trial code more general almost any stimulus can be displayed given its bitmap C Picture The template Picture is almost identical to Text except that images are loaded from BMP or JPEG files and displayed instead of text D EyeData This template introduces the use of the link in transferring gaze position data This data can be used for gaze contingent or gaze control type paradigms Gaze position data can be transferred in real time or played back after recording has ended which helps to separate recording from analysis The Eyedata template uses link data to display a real time gaze cursor The data is then played back after the trial drawing the saccade paths and fixation points to the screen The bitmap for the trial is a grid of letters E GCWindow The most useful real time experiment i
171. the eye that is on the same side as the illuminator For instance if the illuminator is to the left of the camera the largest lateral movement range will be associated with the subject s left eye Place one of the EyeLink Remote target stickers on the subject s forehead see Figure 3 9 just above the eyebrow of the tracked eye so that both the eye and the sticker stay within the camera image when the subject s head moves throughout the expected range If the target sticker is placed too low on the forehead see middle panel of Figure 3 9 a red horizontal bar will be displayed in the global view of the camera image on the Camera Setup screen and an EYEDIST error will appear on the status panel on Offline Calibrate Validate Drift Correct Output and Record screens If the target sticker is placed too far toward the temple see bottom panel of Figure 3 9 the tracker may report an ANGLE error in the status panel when the subject moves too far in the direction of the sticker One other potential problem concerns occlusion of the pupil image by the nose when the subject s head is rotated If this presents a problem because the majority of a stimulus involves the subject looking to the side of space where the illuminator resides opposite the camera consider tracking the eye on the same side of space as the camera One side of space will still afford a relatively more restricted view due to occlusion of the eye by the nose but now the rest
172. the pupil position on the global view of the camera image to acquire the pupil position e Focus the camera image if it looks blurred e Set the threshold with the A key and fine tune with f and U keys Have the subject turn their head to check eye corners e Press Cc to start calibration press ENTER to collect first fixation let sequence run by itself Press ENTER to accept result ESC to repeat e Press V to start validation press ENTER to collect first fixation let sequence run by itself Press ENTER when finished e Repeat calibration if validation is poor e Press O to record eye movement data G on Display PC keyboard toggles the gaze cursor on and off e Press CTRL ALT Q to exit the EyeLink 1000 Host PC application e Turn off the Host PC and the power to the camera at the end of the day 3 14 Experiment Practice The TRACK EXE program is the most flexible way to practice the EyeLink 1000 setup allowing almost any sequence of actions to be performed In real experiments the sequence of actions is much more defined Usually the experiment begins with subject setup and calibration from the Setup menu perhaps followed by practice trials Then a series of experimental trials are performed sometimes with a drift correction before each trial This flow allows little room for practice and makes it important that initial setup and calibration be performed corre
173. ther languages are supported as well such as Python and anything with access to the Windows Common Object Model system COM For full details and links to downloadable resources visit and join the SR Research support forums at http www sr support com The Display PC e runs experiment application software for control of the EyeLink 1000 tracker and stimulus presentation through the EyeLink programming API or SR Research Experiment Builder allowing development of countless experimental paradigms e can configure and control the EyeLink tracker and have access to real time data including gaze position eye movement events and response box button presses with minimal delay and low variability in timing e runs applications focused on stimulus generation and control of the experiment sequence Relying on the Host PC for data acquisition and registering responses makes millisecond accurate timing possible even under Windows e supports data file viewing and conversion tools such as EyeLink Data Viewer and EyeLink EDF2ASC converter to assist researchers in deep analysis of the data obtained Introduction 2005 2009 SR Research Ltd Desktop Mount Level Desktop Mount Angled Figure 1 2 EyeLink 1000 Desktop Mount with Camera Level and Angled 1 2 3 EyeLink 1000 Camera Mount Configurations The EyeLink 1000 is available in five base hardware configurations Desktop Tower Arm Primate and Long Range Mounts These confi
174. tion recording parse type GAZE saccade velocity threshold 30 saccade acceleration threshold 8000 saccade motion threshold 0 1 saccade pursuit fixup 60 fixation update interval O Psychophysical configuration recording parse type GAZE saccade velocity threshold 22 saccade acceleration threshold 3800 saccade motion threshold 0 0 saccade pursuit fixup 60 fixation update interval O 4 3 10 Reparsing EyeLink Data Files The Host PC parses data in real time in order to make eye events immediately available to the Display PC These events are recorded in the EDF file for later access by the DataViewer The parameters used during the initial parsing are supplied in the REMPARSE INI for the EyeLink Remote and in PARSER INI for all other modes of recording Occasionally researchers wish to evaluate the data using different parametric definitions The EyeLink 1000 Host PC software Version 4 0 or later supports reparsing existing EyeLink 1000 EDF files To do this save the desired saccade detection configurations into a new INI file Copy the original EDF file to the current EyeLink host directory C ELCL EXE by default From the DOS command prompt type ELC reparse SOURCE EDF DEST_EDF c coni guration INI ILE where SOURCE EDF is the name of the original EDF file IDEST EDF is the name of the destination EDF file where the parsed data should be saved iconfiguration INI FILE the
175. tion units degree 4 9 3 1 Samples Recorded in Corneal Reflection Mode If the data file being processed was recorded using corneal reflection mode each sample line has an added 3 monocular or 5 binocular character fields after all other fields including resolution and velocity if enabled These fields represent warning messages for that sample relating to the corneal reflection processing Data Files 2005 2009 SR Research Ltd e MONOCULAR Corneal Reflection CR Samples 1f no warning for sample first character is I if sample was interpolated second character is C if CR missing third character is R if CR recovery in progress e BINOCULAR Corneal Reflection CR Samples if no warning for sample first character is I if sample was interpolated second character is C if LEFT CR missing third character is R if LEFT CR recovery in progress fourth character is C if RIGHT CR missing fifth character is R if RIGHT CR recovery in progress 4 9 3 2 Samples Recorded with the EyeLink Remote Data files recorded using the EyeLink Remote have sixteen extra columns to encode the target distance position and eye target status information The first three columns are target x X position of the target in camera coordinate Returns MISSING DATA 32768 if target is missing target y Y position of the target target distance Distance between the target and camera in millimeters
176. tory where it is stored and call it directly by typing the following two lines at the command prompt CD C ELCL EXE ENTER ELCL EXE ENTER 2 2 Modes of Operation The EyeLink 1000 is a multipurpose high resolution real time processing system It is designed to be used in two different operating modes Link In Link mode the eye tracker can be controlled by the Display PC via commands sent over the Ethernet link The degree of Display PC control is dependent only on the display application itself With appropriate programming EyeLink 1000 Host Application 2005 2009 SR Research Ltd it is possible to have full control of the tracker via the Display PC The SR Research Experiment Builder software and various low level programming interfaces have been designed to facilitate interacting with the Host PC A common scenario is to have the application on the Display PC control the eye tracker to start subject setup and calibration while the operator uses the EyeLink Host PC s keyboard to remotely monitor and control data collection perform drift correction and handle problems if they occur Standalone In Standalone mode the eye tracker is an independent system controlled by the operator via the Host PC tracker interface and keyboard The Host PC is still connected to a display generating computer for the purpose of displaying calibration targets only There are two possible data output modes when running the EyeLink 1000 as a st
177. ts The EDF files contain two streams of data eye position samples up to 2000 per second produced from the EyeLink tracker depending on the system model and events eye movement events such as saccades and fixations subject responses and synchronizing events from the experimental application Both streams are time synchronized for easy analysis The file is organized into blocks of data one for each recording session Each block may have samples events or both Also the data items recorded in each sample or event may be configured at recording and are available at the block start to aid in analysis Samples are time stamped in milliseconds and contain monocular or binocular eye position data in eye rotation angle HREF or display gaze coordinated GAZE Pupil sizes as area or diameter are also recordable Samples may also contain eye movement resolution used to compute true velocity or saccadic amplitudes button presses or the status of digital inputs Eye movement events record eye position changes identified by the EyeLink tracker s on line parser such as fixations blinks and saccades Both the onset and end of these events are marked allowing samples to be assigned to eye movement periods without complex algorithms Important data for analysis such as average position for fixations and peak velocity for saccades is also recorded in the events Other events record subject responses such as button presses and synchronization
178. ttern and range An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd If the cursor jumps continuously and rapidly or disappears intermittently the setup for the eye has problems The eye movement condition is also visible at the right side of the status bar at the bottom of the Host PC s display When the pupil appears stable to accept the first fixation press the Accept Fixation button or the ENTER key or spacebar key The pupil tends to come to rest gradually and to make small vergence movements at the start of the fixation so do not respond too quickly However do not wait too long before accepting the fixation as subjects soon begin to make involuntary saccades The proper timing is best learned by watching the gaze cursor during validation discussed later The EyeLink system helps prevent improper triggering by locking out the J key if the eye is moving Sometimes the J key will be locked out because of poor camera setup with the pupil noisy or undetected in some positions You can use the fl and U keys to change the threshold if required If this fails press the ESC key to exit back to the Camera Setup menu After the first fixation has been accepted several more calibration targets are displayed in sequence and fixations for collected each The EyeLink calibration system presents these targets in a random order which discourages subjects from making saccades away from the current target b
179. types e END time types RES lt xres gt lt yres gt START lines mark the beginning of a block of recorded samples events or both The start time is followed by a list of keywords which specify the eye recorded from and the types of data lines in the block The eye recorded from is specified by LEFT for left eye RIGHT for right eye and both LEFT and RIGHT for binocular The types of data lines included are specified by SAMPLES for samples only EVENTS for events only and both SAMPLES and EVENTS for both END lines mark the end of a block of data The types are specified as it is possible to turn recording of samples and events on and off independently However this is not suggested and for most applications the types in the END line can be ignored The two values following the RES keyword are the average resolution for the block if samples are present it is computed from samples else it summarizes any resolution data in the events Note that resolution data may be missing this is represented by a dot instead of a number for the resolution 4 9 3 6 Fixations e SFIX eye lt stime gt e EFIX eye lt stime gt etime dur lt axp gt lt ayp gt aps e EFIX eye lt stime gt etime dur lt axp gt lt ayp gt aps xr lt yr gt The start of fixations are reported with a SFIX line which can be eliminated with the EDF2ASC nse option The eye is L
180. uld require little maintenance under normal use If the IR mirror is dusted it can be cleaned with the cleaning cloth we supplied If the mirror is dirty e g smudged with finger prints please apply some cleaning solution we supplied and then wipe clean with the cloth The forehead rest and the chinrest pad may be wiped with a damp cloth if cleaning is required Additional replacement pads can be purchased please contact SR Research for details 5 2 Storage and Transportation Between uses it is recommended that the EyeLink 1000 be left mounting on the table If the EyeLink 1000 system is not going to be used for an extended period you may wish to disconnect the cables from the computer and pack them in the shipping case The EyeLink 1000 high speed frame grabber Ethernet card as well as the optional Analog card may be left inside the Host PC although it may be removed if this computer is going to be used for another purpose to prevent theft or loss Important The Tower should only be held by the vertical posts and should NEVER be held by the mirror or the components attached to the mirror We recommend you have somebody available to assist you mounting the head support Tower onto the table to prevent damages to the IR mirror or other parts of the Tower For long term storage shipping or transportation it is recommended that the EyeLink 1000 Tower mount or Desktop Mount and cables be stored in the shipping box that you origi
181. upil position and double click on the left mouse button The camera image for the eye should now be displayed in the zoomed view If the pupil is detected a green box and the cross now will be drawn on the eye image Please note that for most subjects you will just need to adjust the height of the chinrest and chair to get the intended camera image without changing the Desktop Mount settings However for subjects wearing glasses depending on the shape and reflection of the glasses you may need to make slight adjustments to the Desktop Mount e g moving the camera closer to the subject lowering the position of the camera and adjusting the angle of the illuminator and camera so that reflections from the glass will not interference with pupil acquisition The left panel of the following figure illustrates a good camera setup whereas the reflections in the right panel block the pupil image especially when the subject looks in the direction of the glass reflection An EyeLink 1000 Tutorial Running an Experiment 2005 2009 SR Research Ltd Figure 3 6 Camera Setup with Subjects Wearing Glasses the EyeLink 1000 Monocular Mount If the image becomes too dark or too light wait one second while the auto contrast adjusts itself If the blue thresholded area in the display is interfering with setup press the Threshold Coloring button or T on the keyboard to remove the threshold color overlay In TRACK EXE you can use keys on
182. ves running many subjects through a sequence of experimental trials with tens or hundreds of recording blocks per file This is best done by remote control over the link from an experimental application The connection from the Display PC to the EyeLink 1000 tracker is implemented by an Ethernet link Refer to the EyeLink Programmer s Guide or SR Research Experiment Builder User Manual for details on how to use the Display PC software to set up and record EDF files 4 3 The EyeLink On Line Parser The EyeLink 1000 system incorporates a unique on line parsing system which analyzes eye position data into meaningful events and states saccades fixations and blinks For many experiments such as reading or cognitive research only the events need to be stored in the EDF file reducing its size by 80 to 95 4 3 1 Parser Operation The parser uses velocity and acceleration based saccade detection methods Because of the EyeLink 1000 tracker s exceptionally low noise levels and high spatial resolution very little data filtering is needed and thus delay is kept small The 250 500 1000 or 2000 Hz sampling rate gives a high temporal Data Files 2005 2009 SR Research Ltd resolution of 4 2 1 or 0 5 millisecond Note Availability of some sampling rates and options depends on the system model For each data sample the parser computes instantaneous velocity and acceleration and compares these to the velocity and acceleration thresholds
183. xample E2A BAT will make the use of the translator easier The following table lists commonly used options l or nr outputs left eye data only if binocular data file r or nl outputs right eye data only if binocular data file Sp outputs sample raw pupil position if present sh outputs sample HREF angle data if present Sg outputs sample GAZE data if present default res outputs resolution data if present vel outputs velocity data in samples if possible s Or ne outputs sample data only Or ns outputs event data only nse blocks output of start events nmsg blocks message event output neye outputs only non eye events for sample only files miss string replaces missing data in ASC file with lt string gt setres xr uses a fixed lt xr gt lt yr gt resolution always yr defres xr uses a default lt xr gt lt yr gt resolution if none in lt yr gt file 4 9 The ASC File Format The ASC file format is defined by the type of data lines that appear in it the format of these lines and the order in which these lines occur Data lines consist of several types e Blank or comment lines which are ignored The first non blank character on a comment line is one of or 3 e File preamble or file description lines These begin with Usually these lines are ignored when processing the ASC file e Sample data lines Each line begins with a number representing the time of the sample e Ev
184. y after each calibration the accuracy of the system in predicting gaze position from pupil position is scored If performance is poor the calibration should be immediately repeated In a validation targets are presented on the subject display in a random order similar to the calibration procedure When the subject fixates these the calibration is used to estimate the gaze position of the subject and the error difference between target position and computed gaze position is estimated Note a scaling factor is built in for automatically generated validation points to pull in the corner positions see the validation corner scaling command setting in the CALIBR INI file This is used to limit validation to the useful part of the display The gaze position error comes largely from errors in fixation data gathered during the calibration which come from two sources the eye tracking system and physiological eye movement control The EyeLink system has extremely low pupil position noise and very high resolution These common sources of error in the eye tracking system are virtually eliminated One physiological source of calibration inaccuracy is the natural variability in fixation position on targets Vergence eye movements also contribute For calibrations with 9 targets it is highly likely that one or more targets will be fixated with an error of 1 or greater Poor eye camera setup can cause a highly distorted calibration pattern Some subj

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