- Turn on floor lamp – top lamp on maximum brightness (three clicks). Don't use overhead lights; they suck.
EyeLink 1000 Eyetracker
- Plug in the power supply to the eye tracker
- Remove the lenscap
- Turn on Tracker PC
- Choose “Eyelink” from the startup menu
- (From the DOS prompt, you can type elcl)
- Turn on ; open experiment (and enter relevant subject information, this is just like in the 4th floor lab except there are additional parameters like whether the subject wears contact lenses, eye-glasses, eye-makeup). Note The subject codes must be less than 6 characters.
- Sit the participant 50-60 cm from the eyetracker
- If the participant wears glasses, clean them with a lenscloth. Dirty glasses = no track
- Place the sticker about an inch above the participant’s right eyebrow (see pp 58-59 of the manual for example)
- When the eyetracker program comes on, adjust the participant/camera to make it look like the pictures in the manual: (e.g., p. 56 – note that the example is for left eye; we’re tracking the right eye).
- Make sure participant’s right side is showing up as the right side in the camera image (if it’s flipped, restart program)
- Make sure eye tracked is set to "Right"
- Focus the camera (p. 54)
- Adjust pupil (up-down arrows) and corneal reflection (CR) (+/-) thresholds until the eye is stable (see pp. 68-70)
- Make sure the status panel displays everything in solid green (e.g., p. 58-top)
- Ask subject to look at the four corners of the monitor, in turn, and make sure the pupil fix is not being lost at any point.
- The pupil and forehead sticker should have crosshairs on them at all times. During calibration and data acquisition, you should see a yellow circle (pupil) and a bullseye (sticker) indicating that both are being tracked (p. 61)
The only times the pupil should be lost is when subject blinks.
Calibration and Validation
- Press C to start calibration.
- Tell participant to look at each dot that comes on, without moving his/her eyes.
- Press “enter” to accept each fixation point
- The calibration routine will only accept a point when the pupil is stable.
- If the pupil status keeps showing up as red (moving), readjust the pupil and/or CR threshold –you can do this by using the up/down and +/- keys without existing out of the calibration
- To redo a calibration point, press Backspace
- When calibration is done, the +’s should form a square or rectangle (see p. 74). If they are messy, redo calibration
- After calibration, validate the fix.
- Validation points should be within 1-2 degrees.
- After passing validation, click accept
#To start experiment, click Output/Record
During the study
- Monitor the subject’s eyes during the study.
- Recalibrate anytime drift-correction is off or if the track gets messy (going off the sides of the screen, etc.) ( press “C” on the laptop to re-calibrate)
- Go back to the “camera setup” screen and repeat the calibration/validation sequence.
- When done recalibrating, press “output/record” to continue. Make a note of which trial this was done.
- Cover lens with lenscap.
- Exit out of the eyetracking program
- Turn off tracking computer
- Unplug power supply from eyetracker
- Don’t forget to remove the sticker from the participant’s forehead!
- If the subject is wearing glasses, reflections from the glasses may interfere with the pupil lock. You may need to adjust the position of the tracker angle (probably move it a bit closer and tilt it up). Also, make sure the subject’s eyeglasses are clean!
- If tracking computer hangs, press the small button below the bigger (power) button on it to reboot. It should never hang… it might look like it’s frozen. In this case, click ‘abort trial’ and then restart the experiment. When the experiment restarts, tracker will reconnect.
- If testing computer (laptop) hangs, try Ctrl-C. If the keyboard doesn’t respond, hold the power button for ~5 secs until computer turns off; then press it again to turn it back on
- If you bump the surge protector and everything shuts off, don’t panic.
- Just flip the switch on the surge protector to off (so you don’t zap anything)
- unplug the power supply to the eyetracking computer (I usually unplug the part that plugs into the physical computer, not the surge protector), and plug back in
- unplug the power supply to the eyetracker itself ,and plug back in
- Turn the eyetracking computer back on just as you would if you were starting the study again/re-setup. It should be fine =)
Pictures coming soon!
--Ala 18:10, 20 October 2011 (CDT)