Eyetracking- eye L not found

Anupama

Hi all,

Since I'm a beginner, I had some very basic questions. I apologize if they're answered already but here goes:

I need to do some eyetracking analysis for my experiment. I'm using opensesame to run my experiment and logging my events through the pygaze plug-in. I managed to extract some EDF files and I'm now trying to run these files through another file that reads the EDF data. However, I encounter an error which says 'requested eye L not found in block 0'. Maybe this error is specific to my experiment but does this mean it's not tracking the left eye? If yes, how can I make it do so? Through my code in OpenSesame or the file that reads the EDF data? Or something else altogether?

Thanks in advance!

Anupama

Daniel

Hi Anapuma,
The format or syntax of the EDF file that comes out of OpenSesame is standard. There's not much that OpenSesame can change about this, except maybe for the content of messages. I think there are two possibilities here:

1. The left eye did not get registered correctly altogether by the eye tracker. Make sure it is configured correctly; for instance make sure it is not the right eye which is being tracked, or make sure the camera image on the EL computer shows a robust pupil detection.
2. There is an error in your analysis script. It may be that it is old and the EDF syntax has changed in the mean time (though unlikely) or it contains other types of errors.

In these cases it's always best to ask for help to people who have experience in doing eyelink studies in your surroundings. They might have bumped into this problem too and quickly know how to solve it.
Good luck!

Anupama

Hi Daniel,

Thank you for your reply!
Yes, maybe it's better to approach someone experienced to help me with the problem.
But I was also wondering how I can ensure that the correct eye is being tracked by the eyetracker? I'm guessing this is not something I can adjust through my code? (Seems unlikely) But I just wanted to confirm, for future reference.

In any case, I will ask for help from someone doing eyelink studies too!

Thanks again!
Anupama

sebastiaan

Hi @Anupama,

It sounds like you're using a custom analysis script to read the data file, right? In that case, the script probably just assumes particular settings, such as that the left eye is tracked.

But I was also wondering how I can ensure that the correct eye is being tracked by the eyetracker? I'm guessing this is not something I can adjust through my code? (Seems unlikely)

You actually can: pylink has functions to toggle between binocular and monocular recording, etc. You can change pretty much all settings programmatically through pylink. If you want to do that, you'll want to grab the pylink manual from the SR Research forum:

• https://www.sr-support.com/

But, if I remember correctly, you can also just enable binocular recording through the EyeLink setup screen. That's probably easier.

Cheers,
Sebastiaan

Anupama

Hi Sebastiaan,

Thank you for your reply! I did consult with my supervisor about the issue and turns out the custom analysis script had to be tweaked a little to read the output.
But this information is also handy, since I would continue working with EyeLink in the future. So, thank you for the reference!

Regards,
Anupama