EyeLink 1000
SR Research has just released their newest model of EyeLink system — the EyeLink 1000.
According to the website, the sampling rate is is 1000Hz, with guaranteed timing of samples. The sampling delay — time from image being captured by the camera to eye coordinates becoming available to the computer — is 2ms, which is down from the typical 6ms figure in EyeLink 2. It’s not clear whether this is with or without filtering. This means that the bottleneck in gaze-contingent or saccade-contingent display changes studies will be the CRT’s refresh rate, rather than eye tracker delays.
It uses the dard-pupil pupil-corneal reflection (CR) method, which should tolorate certain degree of head movements.
As with previous versions of Eylink, the system has very high resolution. The figure given for EyeLink 1000 is 0.01º in pupil-CR 1000 Hz tracking mode. Accuracy, measured by repeated calibration, is around 0.25º - 0.5º, much of which is limited by our ability to control our eyes. The following figure gives a distribution of errors.
All look very exciting, except … well, it’s a "head-supported" system, not a head-mounted or a head-free system. In fact, it looks slightly intemidating:
It reminds me of the FourWard DPI trackers. The reason for the heavy machinary at the top is that they have to host a specialized 1000hz infrared camera plus all the IR illuminators, etc.
Overall, it’s an exciting new development in eye movement methodology. SR Research has, again, proven its leadership in the market for high-end video-based eye trackers for physiological and cognitive labs. But EyeLink 1000 is not for everyone, though. I don’t think it’s a replacement for my EyeLink II because its lack of portability (although participants wouldn’t complain about the red marks left by the helmet of EyeLink II).
In a way I wished SR Research had put more creative tallent on developing remote eye trackers. There are some impressive systems out there — such as the Tobii and the LC Technology’s EyeGaze systems, but there is also a lot of room for improvement. The success of Tobii testifies the market demand in this sector. IMOH SR should not become another Fourward, which cornered itself in the highend market that eventually was eroded by new technologies and small, innovative companies — such as SR Research.