EyeLink II
Training Session
Eye Link II System Introduction
and Basic Training Session
SR Research Ltd.
Mississauga - Ottawa, Canada
Copyright of SR Research Ltd., 2001 - 2002
Agenda
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EyeLink II
Training Session
Functional System Overview
System Architecture
Eye Tracking Experiment Process
Software Architecture
EyeLink EDF Data/Data Viewer
EyeLink Gaze Overlay
EyeLink Support
Copyright of SR Research Ltd., 2001 - 2002
Functional System
overview
EyeLink II
Training Session
•Binocular / Monocular
•250 / 500Hz
•Corneal Reflection vs. Pupil Only
•Head tracking / Head-free Recording
•Real-time Data Access
•Windows API and Experiment
Builder
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
High Speed Eye Tracking System
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EyeLink II Key Features
High Speed – Binocular Recording at sampling rate of
250 or 500Hz.
Exceptional Resolution <0.01°, and low noise <0.01°
RMS.
Accurate - Average gaze position error <0.5°.
2 Modes of Operation - Pupil-Only or Pupil-Corneal.
Headband assembly is lightweight robust and
ergonomic.
Compatible with most eyeglasses and contact lenses.
Easy Set-up, Calibration, and Validation.
Real-time operator feedback.
Online analysis of data into saccades, fixations, and
blinks.
Powerful Application Programming Interface (API).
Compatible with EyeLink I applications.
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
System architecture
EyeLink II
Training Session
Host PC  Data flow / integration  Display PC
Copyright of SR Research Ltd., 2001 - 2002
Host Application
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EyeLink II
Training Session
Runs on ROM DOS environment
Performs image analysis, eye event parsing, and data
recording functions
Allows the system operator to view real-time gaze
position overlaid on a static display representation while
data recording is being performed
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Allows preference selection, camera setup, calibration,
and recording functions
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Facilitates for the selection of 5 different calibration
types (3pt - 13pt)
Copyright of SR Research Ltd., 2001 - 2002
Display API
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EyeLink II
Training Session
Integrates calibration, gaze position collection, head position
compensation, and saccade and fixation analysis into one step
Gaze position is overlaid on experiment graphics in real time,
allowing validation of calibration accuracy before recording and
monitoring of data quality during data collection
Perform drift correction at any time
Time stamped experiment event messaging; Dedicated Ethernet
connection between Host and Display so no data is lost
Allows the user to focus on stimulus presentation and data analysis
Copyright of SR Research Ltd., 2001 - 2002
Eye Tracking
experiment process
•Pre-Experiment activities
•Participant setup
•Calibration
•Validation
•Running the experiment
•Drift correction
•Trials
•Blocks
•Recording and Data Acquisition
•Data analysis
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
Pre-Experimental
Activities
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EyeLink II
Training Session
EyeLink II is provided with several system
configuration (.ini) files, which are designed to help
the Experimenter control the tracker.
Before starting recording eye movements, it is critical
to properly set-up the eyes and head cameras, and to
calibrated/validate the subject.
A poor system set-up will result in a low data
accuracy.
One of the most useful screens is called Set Options.
Often it is overlooked.
Copyright of SR Research Ltd., 2001 - 2002
Pre-Experimental
Activities
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
EyeLink II
Training Session
Copyright of SR Research Ltd., 2001 - 2002
Participant Setup
- Headband
The Headband placement
becomes a smooth and fast
procedure with practise: learn
on yourself and test on
colleagues before running an
experiment. It should take less
than 2 days of practise.
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
Participant Setup
- Eye Cameras
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
Participant Setup
- Head Camera
EyeLink II
Training Session
Please, adjust the monitor or participants
height till you reach this result
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
Participant Setup
- Optimal Eye View
Too Far
Too Close
Camera too High
Camera too Low
Optimal
Pupil too High
Pupil too Low
Copyright of SR Research Ltd., 2001 - 2002
Participant Setup
- Eye in Focus
Not focused
EyeLink II
Training Session
Focused
Copyright of SR Research Ltd., 2001 - 2002
Participant Setup
- Eye Threshold
EyeLink II
Training Session
Fig. 1
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 (fig.1), while a
threshold too high will result in a noisy
signal (fig. 2).
Copyright of SR Research Ltd., 2001 - 2002
Fig. 2
Experiment Setup
Calibration
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
EyeLink II
Training Session
Experiment Setup
Calibration
Good
poor
Copyright of SR Research Ltd., 2001 - 2002
Experiment Setup
Validation
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
Experiment Setup
Validation
Good
Poor
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
Running Experiment
EyeLink II
Training Session
Trials:
•Smallest unit or presentation of a display
•Try to perform a drift correction for each trial
Blocks:
•Many trials make up a block.
•Try to arrange a short break between blocks and
check whether re-calibration is necessary.
Data Recording
Data Analysis – Selective filtering based on application
Copyright of SR Research Ltd., 2001 - 2002
Running Experiment
Drift correction
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
Running Experiment
EyeLink II
Training Session
Avoiding Large Drifts
•Headband slippage
•Make sure that headband is not placed too far forward
•Suspend the cable from above the subject or clip it to
the back of the subject's collar
•Head or Body Movements
•Sit still and avoid major head/body movements
•Use chin-rest
•Supply a comfortable, stable chair
•Pupil Occlusion
•Check the positions and alignments of the camera and
subjects' eye positions
Copyright of SR Research Ltd., 2001 - 2002
EyeLink Recording Data
•EDF File
•Use EDF2ASC converter to get ASC file
•Use EyeLink Data Viewer for analysis
•What’s recorded?
•Samples
•Events
•Messages
•Buttons
•Saccades
•Fixations
•Blinks
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
EyeLink Recording Data
EyeLink II
Training Session
ASC File structure
MSG
62792716 TRIALID PIX1 Normal
START
62797388
PUPIL
AREA
EVENTS
GAZE
RIGHT
EVENTS
RIGHT
TRACKING P
FILTER
2
SFIX R 62797396
MSG
62797517 3 DISPLAY ON
MSG
62797517 SYNCTIME 3
BUTTON
62797525
EFIX R 62797392
5
0
62797858
470
62797914
58
510.5
382.8
1813
385.5
429.2
128.3
1465
SSACC R 62797860
ESACC R 62797860
503.6
SFIX R 62817356
MSG
62817515 TIMEOUT
EFIX R 62817356
62817614
262
760.0
19.1
END
62817622
EVENT
RES
35.57
36.17
MSG
62817636 TRIAL_RESULT 0
MSG
62817636 TRIAL OK
Copyright of SR Research Ltd., 2001 - 2002
7.97
194.9
EyeLink Recording Data
EyeLink II
Training Session
Samples:
•System time, x, y and pupil size
•With additional velocity, resolution, and CR status
63636348
511.1
383.3
1215.0
513.4
385.9
1622.0
.....
63636352
510.8
382.6
1216.0
513.4
385.9
1623.0
.....
63636356
510.0
382.5
1218.0
513.5
386.1
1624.0
.....
63636360
510.0
382.3
1219.0
513.4
386.3
1625.0
.....
63636364
510.1
382.1
1220.0
513.4
385.8
1626.0
.....
63636368
510.3
382.3
1220.0
513.4
385.8
1627.0
.....
63636372
510.4
382.4
1221.0
513.5
385.9
1631.0
.....
63636376
510.6
382.6
1221.0
513.8
386.2
1630.0
.....
63636380
510.9
382.6
1221.0
514.0
386.2
1629.0
.....
(Please read chapter 4 of the user manual)
Copyright of SR Research Ltd., 2001 - 2002
EyeLink Recording Data
EyeLink II
Training Session
Saccades:
•SSACC: eye, start time
•ESACC: eye, start and end times, duration, start x/y, end
x/y, saccade size, and additionally peak velocity,
resolution
SSACC L 63644396
SSACC R 63644396
ESACC L 63644396
63644424 32 646.9 219.5 853.9
194.8
6.16
394.8
ESACC R 63644396
63644424 32 659.3 212.7 859.6
191.9
5.96
385.6
(Please read chapter 4 of the user manual)
Copyright of SR Research Ltd., 2001 - 2002
EyeLink Recording Data
EyeLink II
Training Session
Fixations:
•SFIX: eye, start time
•EFIX: eye, start and end times, duration, average x/y, pupil
size, and additionally, resolution
SFIX L
63644800
SFIX R
63644800
EFIX R
63644800
63645136
340
150.7
277.4
1853
EFIX L
63644800
63645136
340
134.3
277.7
1518
(Please read chapter 4 of the user manual)
Copyright of SR Research Ltd., 2001 - 2002
Data Viewer
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
Data Viewer
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EyeLink II
Training Session
Three different viewing modes
 Spatial, Temporal and Gaze Cursor Playback
Output detailed reports
 Fixation, Saccade, Interest Area, or Trial
Export Data Views as JPG images
Import multiple recording files into one viewing
session
Supports EyeLink I, II, 1000/2k, and Remote EDF files
Fully integrated with API
Copyright of SR Research Ltd., 2001 - 2002
Data Viewer
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
Data Viewer
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EyeLink II
Training Session
Generate detailed Fixation, Saccade, Interest Area and Trial reports
for further analysis
Copyright of SR Research Ltd., 2001 - 2002
Data Viewer
EyeLink II
Training Session
Monitoring eye data over time
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Create ‘Interest Periods’ to analyze data within
a specified period of time
Define ‘Reaction Time Definitions’ for
automatic trial by trial reaction time calculation
Copyright of SR Research Ltd., 2001 - 2002
EyeLink Support
For more detailed information on our products
and services, visit our website on
www.sr-research.com
or
www.sr-support.com
Send us an email
support@sr-research.com
or call toll free
1-866-821-0731(North America Only)
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
EyeLink Support
Copyright of SR Research Ltd., 2001 - 2002
EyeLink II
Training Session
EyeLink II
Training Session
We will take a
short break.
Then it’s your
turn to get
eyetracking!
Copyright of SR Research Ltd., 2001 - 2002