EyeLink 1000/2k and EyeLink Remote Introduction and Training Session

EyeLink 1000/2k andEyeLink Remote

Introduction and Training Session

SR Research Ltd.Toronto - Ottawa, Canada

AgendaAgenda• Functional system overview

• System architecture

• Eye tracking experiment process• EyeLink recording data / Data Viewer

• Analog card

• EyeLink support

EyeLink CL OverviewEyeLink CL Overview

• Focal Imaging Technology– Large camera field of view– High resolution eye data

• EyeLink CL hardware– EyeLink CL High Speed

Infrared Camera– IR illuminator– CameraLink cable– Custom High Speed Image

Processing Board

EyeLink CL OverviewEyeLink CL Overview

• Extendable Hardware Platform– EyeLink Tower– EyeLink Desktop– EyeLink Primate– EyeLink Remote

• Complete Software Package– Host Eye Tracker Application– Application Programming Interface

EyeLink Tower and DesktopEyeLink Tower and Desktop• Fastest Sampling Rate:

– 2000 / 1000 / 500 / 250 Hz recording

• High Resolution: – 0.01 ° RMS in pupil-CR 1000 Hz tracking mode

• Accurate:– Drift free, down to 0.15° average accuracy (0.25 -

0.5° typical)

• Real-time: – Access eye position data with < 2-ms delay

• Easy: – Fast and simple setup, calibration and validation

• Comfortable: – Head-supported design

• Real-time operator feedback • Compatible:

– With EyeLink I and II display software– Works with E-Prime, Presentation, and other 3rd

party experiment software

EyeLink Tower and DesktopEyeLink Tower and Desktop




• Tower Mount:– Larger tracking range: (55 horizontal, 45 vertically

vs. 32 horizontal, 25 vertical)– Minimal adjustments

• Desktop Mount:– Supports monocular and binocular tracking– Compact, mirror-less mount and more portable– More compatible with glasses– More portable.

System System ArchitectureArchitecture

System System ArchitectureArchitectureHost Application

• Controls the eye tracker•Performs image analysis•Performs data recording •Performs eye event parsing•Configures preferences

• Provides real-time feedback•Gaze view: Gaze cursor on background image•Plot view: Eye traces over time

• Controls other optional setups•Analog output board•Gaze video overlay system

System System ArchitectureArchitectureDisplay PC Software

• Allow full experiment control•Integrates calibration and gaze position collection into one step•Sets any tracker preference•Sends commands to control tracker

• Time stamps experiment events with messages

• Real-time access to eye sample and eye event data structures

• Allows the users to focus on stimulus presentation and data analysis

Eye Tracking Eye Tracking Experiment ProcessExperiment Process

•Pre-Experiment activities•Check Tracker Settings (Set Options Screen)•Participant setup•Calibration•Validation

•Running the experiment•Blocks •Trials•Optional drift correction/drift checking

•Recording and data acquisition•Data analysis

Participant Setup Participant Setup Camera Setup ScreenCamera Setup Screen

Participant Participant SetupSetup

Mirrored Mount The participant setup becomes a smooth and fast procedure with practise. Try to follow the steps below:

1) Set the height of the monitor and height of the tower mount2) Set the eye-selection knob to track the intended eye3) Set the mirror at the intended angle 4) Adjust the chair height as well as the chinrest position5) Find the pupil by clicking on the eye image6) Focus the eye camera7) Adjust the thresholding level for pupil and CR8) Check the setup by asking the subject to look at four

corners9) Calibration, validation and recording

Participant Participant SetupSetup

Desktop Mount The participant setup becomes a smooth and fast procedure with practise. Try to follow the steps below:

1) Place the monitor at the intended distance and height2) Set up the desktop optics; check out the height of the

mount3) Adjust the chair height as well as the chinrest position4) Adjust the camera angle and position 5) Find the pupil by clicking on the eye image6) Focus the eye camera7) Adjust the thresholding level for pupil and CR8) Check the setup by asking the subject to look at four


Participant Setup Participant Setup Optimal Eye PositionOptimal Eye Position

•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 figures on the right shows that the subject is seated too high (top-right) or too low (bottom-right).

Participant Setup Participant Setup Search Limits: when to use and how to enableSearch Limits: when to use and how to enable

• The Search Limits box (red box) can be used to reduce the area of the full camera image that is searched to find the eye.

• Normally the search limits box is not needed, however with some participants glasses it can be used to exclude other regions of the camera image that may otherwise be detected as a pupil / CR reflection pattern.

• The disadvantage of the search limit 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.

Participant Setup Participant Setup Adjusting Search LimitsAdjusting Search Limits

• Press “Use Search Limits” to toggle on /off search limits.

• Use ALT and cursor keys to adjust the shape of the search limits.

• Use SHIFT and cursor keys to adjust the position of the search limits.

Participant Setup Participant Setup Centroid Vs. Ellipse Centroid Vs. Ellipse

Pupil Tracking ModesPupil Tracking Modes

• The Centroid mode tracks the centre of the thresholded pupil using a centre of mass algorithm.

• This modes advantage is that it has very low noise.

• The disadvantage of this mode is eye position can drift if there is significant occlusion of the pupil (for example by eyelids).

• The Ellipse mode determines the centre of the pupil by fitting an ellipse to the thresholded pupil mass.

• The advantage of this mode is decreased drift potential. It can cope well with pupil occlusion.

• The disadvantage is that it has a higher noise level.

Participant Setup Participant Setup Focusing the Eye CameraFocusing the Eye Camera

Focusing Arm Focused Not Focused

Participant Setup Participant Setup

The pupil threshold can be adjusted automatically, through the Auto-threshold command, or manually, through the up/down arrow. A threshold too low will result in shadows (figure.1), while a threshold too high will result in a noisy signal (figure. 2).

Setting Pupil ThresholdSetting Pupil Threshold

Figure 1

Figure 2


Pupil clipped and lost Good Corner Shadow captures Pupil clipped and lost Good Corner Shadow captures pupil pupil

Symptoms of Poor Pupil ThresholdSymptoms of Poor Pupil Threshold


Good Corneal Reflection Poor Corneal ReflectionGood Corneal Reflection Poor Corneal Reflection

Setting Corneal Reflection (CR)Setting Corneal Reflection (CR)

Binocular vs. Monocular MountBinocular vs. Monocular Mount


Participant SetupParticipant SetupSubjects wearing glasses

Good mirror angle Poor mirror angleGood mirror angle Poor mirror angle

Participant Setup Participant Setup Binocular Setup Binocular Setup

Participants with glasses Participants with glasses


Status PanelStatus PanelMonitor the status of camera image of the tracked eye throughout setup, calibration, validation and recording phases. Pupil

OK (green): Pupil present and can be tracked at selected

sample rateSIZE (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

trackedMISSING (red): Corneal reflection is not present

CalibrationCalibrationMapping raw eye data to either gaze position or HREF coordinate

CalibrationCalibration

Always checks for the calibration grid at the end of calibration.

Good Calibration Poor Calibration


Improving calibration accuracy:

• Always ask the subject to look at the four corners of the display after performing the camera setup. Watch for the pupil or CR warning signals on the tracker screen due to pupil occlusion or improper thresholding.

•Ensure that the threshold pupil area be inside the pupil box when the subject is looking at any area of the display.

•The corneal reflection should never be lost or misidentified when the subject looks around the calibrated area.


Improving calibration accuracy (continued):• Encourage the subjects to sit still!

• Subjects who have never been calibrated before require some practice in stably fixating the calibration targets. Try to perform at least two calibrations per subject before beginning to collect data.

• Try to match the background color of the screen during calibration and validation to that of the test displays. Changes in pupil size caused by large brightness differences will reduce recording accuracy.

ValidationValidationChecking gaze accuracy of the calibration

ValidationValidation

Validation 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 tracking.

In general, ensure that the average gaze error is within 0.5 and maximum error within 1.0

RecordingRecordingGaze View

RecordingRecordingPlot View

EyeLink RemoteEyeLink Remote

• Accurate: – 0.5° average accuracy

• Fastest Remote Sampling Rate: – 500 Hz monocular eye tracking

• Real-time: – Access eye position data with 3.0 msec delay

• Head Free: – 22 x 18 x 20 cm (horizontal x vertical x depth)

allowable head movement at a 60 cm camera distance

EyeLink RemoteEyeLink Remote• Reliable Head Distance Tracking:

– Maximum head movement speed of 100 cm / second, even during blinks

• Robust Blink Recovery: – Recovery time of 2 msec

• Online Saccade Detection: – Reliably monitor both fixation and saccade events

of as low as one degree

• Dual Purpose Eye Tracker: – Quickly switch between the EyeLink Desktop and

EyeLink Remote systems.




The participant setup becomes a smooth and fast procedure with practise. Try to follow the steps below:

1) Use proper lens; set the ELCL configuration to “Remote (Level)”;

2) Set the height of the monitor; eye-screen distance at about 70 cm

3) Place the camera right in front of the monitor4) Raised the desktop mount to maximize tracking range.5) Seat the subject and place the target sticker6) Find the pupil by clicking on the eye image7) Adjust the thresholding bias for pupil and CR8) Check the setup by asking the subject to look at four



•Place the target sticker on the subject’s forehead, just above the eyebrow of the tracked eye

•The eye and the sticker stay within the camera image when the subject’s head moves

•An ideal target-camera distance should be about 550 mm to 600 mm

EyeLink RemoteEyeLink Remote Target is too close to the eye vertically Target has a large angle


Pupil threshold bias adjusted by UP or DOWN cursor keys (1.08 typical)CR threshold bias adjusted by – or + keys (1.00 typical) .


• Monitor the thumbnail camera images at the lower left corner of the tracker screen

• The two dots in the middle panel reflect the target and eye position in the global camera image

• For reliable tracking, both dots should stay within the red box.


PupilOK: Pupil present and can be tracked at selected sample rateSIZE: Occurs when the pupil size is larger than the maximum allowed pupil

size or smaller than the required size (e.g., too bright or small pupil)MISSING: Pupil not present

Status PanelCorneal OK: Corneal reflection is present and can be trackedMISSING: Corneal reflection is not present

TargetOK: Target is present and can be trackedMISSING: Target is not present.EYEDIST: Target is placed too close to the eye on the vertical dimension.ANGLE: Target has too large an angle to be recognized properly.

TrackerTracker SettingsSettings

Link/Analog Filter

•EDF File (binary File)•Use EDF2ASC converter to get ASC files•Use EyeLink Data Viewer for direct analysis

•What’s recorded? •Samples•Events

•Saccades•Fixations•Blinks•Messages•Buttons

(Please read Chapter 4 of EyeLink 1000 User Manual)

EyeLink Recording DataEyeLink Recording Data

•Samples • System time, x, y and pupil size• With optional velocity, resolution, and CR status6079861 503.7 680.3 972.0 .....6079862 503.7 680.1 972.0 .....6079863 503.8 680.1 972.0 .....6079864 503.8 680.2 972.0 .....6079865 503.9 680.2 971.0 .....6079866 503.7 680.1 971.0 .....6079867 503.7 680.1 971.0 .....6079868 503.6 680.0 970.0 .....6079869 503.6 680.1 970.0 .....6079870 503.7 680.2 970.0 .....



•Saccades • SSACC: eye, start time• ESACC: eye, start time, end time, duration, start x/y, end x/y, amplitude, peak velocity.

SSACC L 6079955ESACC L 6079955 6079962 8 507.5 682.5 511.9 682.0 0.20 38…SSACC L 6080723ESACC L 6080723 6080763 41 513.8 679.7 633.5 550.5 7.94 285



•Fixations • SFIX: eye, start time• EFIX: eye, start time, end time, duration, average x/y, pupil size, and additionally, resolution.

SFIX L 1454748EFIX L 1454748 1454907 160 510.3 4.1 1187 28.45 27.50...SFIX L 1454919EFIX L 1454919 1455873 955 514.0 0.3 1361 28.40 27.50



EyeLink Data ViewerEyeLink Data Viewer

EyeLink Data ViewerEyeLink Data Viewer

•Excellent Data Visualization•Spatial Overlay, Temporal Graph, and Playback Views

•Flexible Event Filtering•Fixations, Saccades, Blinks, Interest Areas, etc.

•Reaction Time Definition, Interest Period Definitions

•Detailed Output Reports•Fixation, Saccade, Interest Area, Trial, Message, or Sample Reports

•Full Experiment Integration by Messages•Images, Interest Areas, and Trial Condition Variables

EyeLink Data ViewerEyeLink Data ViewerGenerates detailed Fixation, Saccade, Interest Area and Trial reports

Analog CardAnalog Card



• Real-time analog output of x, y position and pupil size data

• Supports analog output and digital input and output

- Digital inputs can be configured to record external synchronization messages to the eye tracker- Digital outputs can be set up to send synchronization signal to external systems

• Ideal in providing real-time data access to any third-party analysis systems that cannot run Experiment Builder and other EyeLink programming API

• Documents•EyeLink 1000 User Manual•EyeLink 1000 Installation Guide•SR Research Experiment Builder•Windows Programmers Guide •EyeLink Data Viewer

• Contact Information•E-mail: [email protected]•Phone: 1-613-826-2958/ 1-866-821-0731•Web: http://www.sr-support.com

EyeLink SupportEyeLink Support

EyeLinkEyeLink SupportSupport

We will take a short break. Then it’s your turn to get

eyetracking!