The eyetracking system in the JEL comprises two
EyeLinkII head-mounted video-based eyetrackers. The official
EyeLinkII site by SR Research is
here.
Useful information regarding the use of the system (and problems, etc.) can be obtained from the
SR Support Forum.
--
FrankKeller - 08 Nov 2005
Some tips for accurate tracking
In a scene description experiment I am currently running, I had a lot of problems with fixations always being recorded above the objects I would have expected participants to be looking at. The solution was scarily simple: for quite a while now, the screen has been tilted forward, rather than vertical. This means that the two lower head-markers are further away from the participant, which will be obvious in a non-rectangular head marker indication. Calibration values can still be fine!
So, before starting an experiment:
- check that the screen is vertical,
- check that the participant is sitting straight in front of it, roughly two arms' lengths' away,
- check that the eyetracker is staight above their nose,
- check that their gaze is roughly to the middle of the screen; otherwise adjust the height of the chair.
All of these points should lead to the IR head markers being in a close-to-perfect rectangle.
In addition, it's a good idea to
- have instruction, calibration, and drift correction screens in the same luminance as the stimulus display,
- remember to take the slack off the cord at the back of the head by pulling it through over the loop on the wooden stand.
Good luck!
--
HeleneK - 15 Oct 2007
Topic revision: r3 - 15 Oct 2007 - 12:01:25 -
HeleneK