Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
Eye Link II System Eye Link II System Introduction and Basic Introduction and Basic
Training SessionTraining Session
SR Research Ltd.
Mississauga - Ottawa, Canada
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining SessionAgendaAgenda
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
EyeLink IITraining Session
•Binocular / Monocular•250 / 500Hz•Corneal Reflection vs. Pupil Only•Head tracking / Head-free Recording•Real-time Data Access•Windows API and Experiment Builder
Functional System overview
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
EyeLink IIEyeLink IIHigh Speed Eye Tracking High Speed Eye Tracking
SystemSystemEyeLink 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 IITraining Session
System System architecture Host PC Data flow / integration Display PC
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining SessionHost ApplicationHost Application
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
Allows preference selection, camera setup, calibration, and recording functions
Facilitates for the selection of 5 different calibration types (3pt - 13pt)
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining SessionDisplay APIDisplay API
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
EyeLink IITraining Session
•Pre-Experiment activities•Participant setup•Calibration•Validation
•Running the experiment•Drift correction•Trials•Blocks
•Recording and Data Acquisition•Data analysis
Eye Tracking experiment process
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
Pre-Experimental Pre-Experimental ActivitiesActivities
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
EyeLink IITraining Session
Pre-Experimental Pre-Experimental ActivitiesActivities
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
Participant Setup Participant Setup - Headband- 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 IITraining Session
Participant SetupParticipant Setup- Eye Cameras- Eye Cameras
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EyeLink IITraining Session
Participant Setup Participant Setup - Head Camera- Head Camera
Please, adjust the monitor or participants height till you reach this result
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
Optimal
Too Far Too Close
Camera too High Camera too Low
Pupil too High Pupil too Low
Participant Setup Participant Setup - Optimal Eye View- Optimal Eye View
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
Participant Setup Participant Setup - Eye in Focus- Eye in Focus
Not focused Focused
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
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).
Fig. 1
Fig. 2
Participant Setup Participant Setup - Eye Threshold- Eye Threshold
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
Calibration
Experiment Setup
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
Experiment Setup
Calibration
Good
poor
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
Experiment Setup
Validation
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
Experiment Setup
Validation
Good Poor
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining 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
Running Experiment
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
Running Experiment
Drift correction
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
Running Experiment
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 IITraining Session
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 IITraining Session
MSG 62792716 TRIALID PIX1 Normal
START 62797388 RIGHT EVENTS
PUPIL AREA
EVENTS GAZE RIGHT TRACKING P FILTER 2
SFIX R 62797396
MSG 62797517 3 DISPLAY ON
MSG 62797517 SYNCTIME 3
BUTTON 62797525 5 0
EFIX R 62797392 62797858 470 510.5 382.8 1813
SSACC R 62797860
ESACC R 62797860 62797914 58 503.6 385.5 429.2 128.3 7.97 194.9
SFIX R 62817356
MSG 62817515 TIMEOUT
EFIX R 62817356 62817614 262 760.0 19.1 1465
END 62817622 EVENT RES 35.57 36.17
MSG 62817636 TRIAL_RESULT 0
MSG 62817636 TRIAL OK
EyeLink Recording DataASC File structure
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
EyeLink Recording Data
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)
Samples:
•System time, x, y and pupil size
•With additional velocity, resolution, and CR status
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
EyeLink Recording Data
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 IITraining Session
EyeLink Recording Data
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
EyeLink IITraining SessionData ViewerData Viewer
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining SessionData ViewerData Viewer
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
EyeLink IITraining SessionData ViewerData Viewer
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining SessionData ViewerData Viewer
Generate detailed Fixation, Saccade, Interest Area and Trial reports for further analysis
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining SessionData ViewerData Viewer
Create ‘Interest Periods’ to analyze data within a specified period of time
Define ‘Reaction Time Definitions’ for automatic trial by trial reaction time calculation
Monitoring eye data over time
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
For more detailed information on our products and services, visit our website onwww.sr-research.com
orwww.sr-support.com
Send us an email [email protected]
or call toll free1-866-821-0731(North America Only)
EyeLink Support
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining SessionEyeLink Support
Copyright of SR Research Ltd., 2001 - 2002
EyeLink IITraining Session
We will take a We will take a short break. short break.
Then it’s your Then it’s your turn to get turn to get
eyetracking!eyetracking!