Page 8: Introduction This section introduces the EyeLink II system, technical capabilities, and supporting documentation. No mirrors are used in the EyeLink II system, making it very robust and easy to set up. Two eye cameras allow binocular eye tracking or easy selection of the subject's dominant eye without the mechanical reconfiguration required by most eye trackers. Page Eyelink Ii Host Pc 1. On- line detection analysis of eye-motion events such as saccades and fixations is also performed.
Page 11 C source code, and instructions for creating experimental applications are provided in the EyeLink II Windows developer kit. Page Eyelink Ii Pci Card 1. The main secondary screens can be accessed via the navigation buttons on the left hand side of the screen. Page 18 Press to view the Help screen, in the help screen there is a brief overview of the role of this page and the key functions for it.
From this screen the eye and head tracking cameras can be set up, and their images can be thresholded. Eye s to be tracked, tracking mode and options can also be set.
Page 20 Here the Right Eye camera is selected. Image thresholds and status are indicated below each thumbnail. After setting up the eye cameras and thresholding, you need to Calibrate the system. Page 22 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 Go to the Offline screen or exit camera setup EyeLink II User Manual version 2.
Page 24 The Diameter is recorded in millimeters. Page 26 EyeLink II settings specified in the defaults. This is still saved even when the PC is turned off.
The Most Accurate, Precise and Versatile Eye Tracker
Load default configuration Default. Page Calibration Screen The eyes to be calibrated as well as the calibration type as defined in the Set Options screen or via the EyeLink API are indicated beside the camera images at the bottom of the screen. The calibration status and current calibration point being presented are indicated on the bottom right of the screen. Page 29 Auto calibration set to the pacing selected in Set Options menu. Auto trigger ON. EyeLink accepts current fixation if it is stable.
If auto trigger is not enabled, repeat this action after each target fixation. Page 31 Auto validation set to the pacing selected in Set Options menu. Page Drift Correct Screen If the drift correction error is too large, the drift correction will be performed again. If the total drift since the last calibration is too large, the drift correct will fail and you will be prompted to perform another calibration. Page Output Screen 2. Page Record Screen 2.
All status flags remain on for a minimum of msec, even if the condition that caused the warning or error to be raised lasted for less than msec. Page Mouse Simulation Mode 2. Page Analog Data Types 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. Page 41 The EyeLink II 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.
The advantage of the Display PC based control is that it allows the operator to work near the subject, or for self-setup.
Almost very 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.
EyeLink 1000 Plus
Page Figure Size And Vertical Eye Camera Adjustments Slide the camera up or down through the rod clamp gently, adjusting the vertical position of the image to keep the eye in view. Remember to re-tighten the rod clamp after the adjustment. Page Figure Horizontal Adjustments Of Eye Camera This may require some practice: try setting up the headband on yourself, while watching the display on the operator monitor.
Page Setting Pupil Threshold Eyeglasses also can show bright images of the IR markers mounted on the subject monitor. These reflections are automatically reduced as much as possible by the EyeLink II system; however not every subject with glasses will be usable. Page Calibration 3. 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. The Host PC display will also display the raw pupil position as a moving colored circle, and a thresholded eye camera image.
Page 51 The proper timing is best learned by watching the gaze cursor during validation discussed later. Page Figure Page Validation difference between target position and computed gaze position is estimated.
Note: since EyeLink II tracker version 2. Page 55 The average of this bias can be used to correct future gaze-position calculations, lowering tracking error.
By accepting the validation the system performs a gaze calculation correction similar to a drift correction using this data. Page Recording Gaze Position This serves as a reference for the gaze-position cursor displayed by EyeLink II during recording, allowing the operator to see where the subject is looking and detect problems with eye-tracking errors or of subject inattention. Page 57 Alternative, an online drift correction can be performed with the aid of a mouse click.
Before recording, add the following line to the final. Page Experiment Practice This flow allows little room for practice, and makes it important that initial setup and calibration be performed correctly and carefully validated. The EyeLink II tracker has a trial-abort menu built in, 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. Run a block of trials.
Page 61 These require high sampling rates and low delay, which the EyeLink II tracker can deliver through the link.
Page 62 The final fourth block presents a white dot, a few seconds later another white dot is shown. The original white dot then fades away.
This presentation pattern is repeated. Page Data Files 4. It is designed to be space-efficient and flexible, allowing for complete records of experimental sessions and data.
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It adapts to monocular and binocular recording, with backwards-compatibility for future enhancements. Page Recording Edf Files Special provisions must be made for display of the calibration pattern. Page Parser Limitations 4. For example, neuro-psychophysical 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. INI can be edited to change the default parameters.
Page Pursuit Thresholds This is acceptable for file data, but is expensive for real-time systems using data sent via the link. Page Other Parameters 0. 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.
Page File Data Types Samples are records of eye-position, pupil size, and button or input states. The EyeLink II tracker can record up to samples per second, from one eye monocular or both eyes binocular.
Setting up eye link 1000 file 1
Each sample is stored as a binary record in the EDF file, with simple compression used to minimize disk space.
Page Position Data Other types of sample data are discussed in greater detail below.
EyeLink II User Manual
It is then processed to compute eye rotation angles and to compensate for subject head motions. These are the most useful coordinates for most applications, but may not reflect true eye-rotation velocities due to head movements. Page Pupil Size Data 4.
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. Page Messages Each button event records a change in state pressed or released, 1 or 0 of up to 8 buttons or input port bits, monitored by the EyeLink II tracker.
For most research, only simple fixation statistics are required, such as average position and pupil size. Page 77 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 II parser computes velocity by use of a 5-sample moving filter, which is equivalent to a differentiator followed by a 2-sample moving average, or a 63 Hz single-pole filter. Similar commands exist for samples and events sent over the link for real-time applications.