[visionlist] New eye-tracker and monitor advice

[Arash Fazl (BU)]

We use an Eyelink II from SR research. It has temporal resolutions of 
250 or 500Hz. It tracks both eyes, and has an accuracy of 0.5 degrees 
(the precision is much better). If you have psychtoolbox 3, you already 
have Eyelink toolbox installed on your Mac (in psychhardware directory). 
They claim that their a scene camera corrects for head movement and you 
don't need to restrain the head. Don't believe it, you should use 
head/chin rest or a biteboard if you need high accuracies.  The head 
band weighs 420 grams.  Their newer systems are advertised to have 1k 
and 2k Hz sampling frequency. Downside: not cheap, our system was $30K. 
Make sure you really need that high frequency, since your stimuli on a 
CRT cannot be faster than 170-200 Hz.
Best,
Arash



vincent ferrera wrote:
> I have several ISCAN trackers that are extremely reliable, but not 
> cheap (~14K/ea).  They have analog outputs for horizontal and vertical 
> eye position, and pupil diameter.  And they support a variety of 
> temporal resolutions (60, 120, 240 Hz), although you trade-off some 
> spatial resolution.  Some of my colleagues use ASL, which has 
> comparable functionality and reliability.
>
> I have built an eye-tracker for under $2000 based on a system 
> developed in Charles Gilbert's lab, but you'd have to contact him for 
> details.
>
> One thing to keep in mind with all eye trackers is that they work best 
> when they have a direct view of the eye and the head is immobile.  We 
> use an IR "hot" mirror to image the eye and a bite bar (UHCO 
> "Headspot") to stabilize the head.  Some systems advertise the ability 
> to compensate for head motion, but this works mainly in demos and not 
> so well in the lab.
>
> In terms of monitors, what's the latest on DLP technology?  I know 
> there was a color-separation issue.  Was that solved by the 3-chip 
> systems?  Are there other issues?
>
> On Sep 5, 2007, at 12:40 PM, Louise Whiteley wrote:
>
>> New eye-tracker and monitor advice
>> ---------------------------------------
>>
>> We are about to purchase a new set-up for visual psychophysics 
>> experiments, and
>> are looking for advice from anyone who is up to date on the relevant 
>> technology
>> - we want both a new monitor, and an eye tracking device.
>>
>> In terms of the monitor we need precise timing, a high refresh rate 
>> and small
>> phosphor decay time, and ideally known calibration properties. In 
>> terms of the
>> eye-tracker, it must be integrable with Psychtoolbox on MacOSX, and 
>> maximum
>> comfort for subjects is desirable for our rather long experiments!
>>
>> Thanks,
>>
>> Louise Whiteley (Gatsby Unit, UCL).
>>
>> -- 
>> Ms Louise Whiteley
>> Wellcome Trust 4yr Neuroscience PhD Student
>> Gatsby Computational Neuroscience Unit, UCL
>> email: louisew at gatsby.ucl.ac.uk
>> tel: +44 207 679 1172
>> fax: +44 207 679 1173
>> address: Alexandra House, 17 Queen Square, London WC1N 3AR
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