eyelink - pupil size

1
We're running an experiment where we would like to have access to pupil size measurements online. I have a couple of questions about the eyelink2 and extracting this data.

(1) I've looked into the structure returned from:
evt = Eyelink('NewestFloatSample')
and can't seem to find a pupil size reference or size data there. It may be that I'm being dense, but where/how can I extract the pupil size measurement from the eyelink online?

(2) The pupil size measurement is a relative value in some arbitrary units. If we wish to convert this value to an absolute estimate of the size of the pupil, we need to calibrate the system. We have observers on bite bars, with the head (and eye) fixed in a known location. The camera is mounted in front of them. So, the distance from the camera to the eye is a known amount. If anyone has any experience/suggestions to convert the eyelink value to a metric estimate of pupil size I would love to hear from you.

Thanks a lot.

Kevin MacKenzie
Bangor University
2
thanks for the info!

Kevin


--- In psychtoolbox@yahoogroups.com, "e_flister" <e_flister@...> wrote:
>
> > (1) I've looked into the structure returned from:
> > evt = Eyelink('NewestFloatSample')
> > and can't seem to find a pupil size reference or size data there. It may be that I'm being dense, but where/how can I extract the pupil size measurement from the eyelink online?
>
> the normal eyelink data doesn't include pupil size, but frans and mario added this feature back in 10/2006.
>
> here's the message where i requested the feature and explain how to configure the eyelink to send you the extended data:
> http://tech.groups.yahoo.com/group/psychtoolbox/message/5156
>
> here's the message where they released the new feature:
> http://tech.groups.yahoo.com/group/psychtoolbox/message/5336
>
> i'll use this opportunity to ask another favor of mario -- i was holding off cuz i owe him some audio demos. they are almost ready to go and just need comments -- i'll submit them this week! but it turns out that the above fix only gives us the extended data for the *most recent* eyelink sample, and we would like to be able to get the extended data for all the samples that have queued up since the last query. this requires a 'GetFloatDataRaw' function -- i've written all the code and have submitted it to the files section as an svn patch ('eyelinkPatch.patch'). i was hoping mario wouldn't mind adding it to the build? i didn't want to attempt my own build -- don't have visual studio, etc. i couldn't test without building, but the additions are very straightforward, and i'm happy to volunteer to test the next release... frans might want to take a quick look and see if he approves too?
>
> -e
>
3
> if you tell me how to apply the patch, i.e., in
> which directory do i have to 'cd' and what exact
> patch command to use (sorry, i'm too lazy to
> look this up myself), i'll apply the patch, give
> it a quick sanity check and build it for you
> when i find the time.

thanks a ton! i was down with a cold, but am back in the game so i'll finish up the audio demos tonight.

the directory is the top-level osxptb directory, but it looks like svn can't read/merge from unified-diff files, even though it can produce them using svn diff. i thought patches were an svn concept, but it turns out they are a tortoise concept. according to the part of the tortoise manual that describes the underlying svn commands:

http://tortoisesvn.net/docs/release/TortoiseSVN_en/tsvn-cli-main.html#tsvn-cli-applypatch

"Applying patches is a tricky business unless the patch and working copy are at the same revision. Luckily for you, you can use TortoiseMerge, which has no direct equivalent in Subversion."

so, if you don't mind using windows and installing tortoise (which i think is really useful anyway), i think this is the easiest option. you can right click the patch file, click 'tortoiseSVN > apply patch...', select the top level osxptb directory, then right click in the little 'patches' window and say 'patch all'.

here's the link to tortoise:
http://tortoisesvn.net/downloads

alternatively, on unix, i think the following will work from the top level osxptb directory:
$ patch < patchfile
or maybe
$ patch -p0 < patchfile

see: http://en.wikipedia.org/wiki/Patch_(Unix)
and: http://svnbook.red-bean.com/en/1.5/svn-book.html#svn.branchemerge.basicmerging.stayinsync
i haven't verified this works -- i'll check on my osx box at home.

if neither of these is acceptable, i think i'll have to send you individual files.

> Which is the preferred test OS? I'd first only
> recompile one variant for testing.

windows. (sorry).

> Btw. Frans Cornelissen is the designated creator and
> master for all eyelink toolbox issues.

i figured he'd see the posts and chime in, but since he didn't i'll email him to see if he has any input... like i said, i'm happy to do the testing...

thanks again! we really appreciate the help. let me know if applying the patch continues to be a problem...
-e
4
> or maybe
> $ patch -p0 < patchfile

ok, this works for me on osx. -p0 is necessary.
-e