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Measuring pupil size during n back task

KerenKeren Posts: 5

Hey,
I am quite new to Open Sesame and to Pyton and to eye tracking, so sorry if my question is basic. I created the experiment based on a PyGaze template. I use eye tribe. The pygaze_start_recording collect all the information from the eye tribe, including the pupil size or do I need to specify exactly what I want ? In case I need to specify, could you guide me how to do it ?
Thanks a lot for your patience,
Keren

Comments

  • eduardeduard Posts: 764

    Hi Keren,

    As far as I know, pupil data is logged by default. Once you have a log file, you can check this post by Edwin. There he explains what a eyetribe logfile contains.

    Good luck,

    Eduard

  • KerenKeren Posts: 5

    Hey Eduard,
    Thanks for your quick answer. Another question if you don't mind:
    I noticed that there is drift correction at the beginning of each trial, I assume it is necessary (sorry, first time using eye tracker), during which a fixation cross is presented. My question is whether I can use this drift correction fixation cross as pre-target fixation and assign to is different durations (ranging from 900-1800 ms) ? I hope it makes sense.
    Thanks a lot ! Keren

  • eduardeduard Posts: 764

    Hi Keren,

    The drift correct is there to ensure that the eye tracker calibration is still sufficient. It is always good to have to have an indication of whether something bad happened (big movement, etc..). Having it for every trial is probably a little overkill, at least if you have short trials and short blocks.

    My question is whether I can use this drift correction fixation cross as pre-target fixation and assign to is different durations

    As far as I know, this is not possible. For one, there is no option, so you would have to write your own function and hack into underlying pygaze software to make it happen. Second, and more importantly, a drift correct is either triggered by fixation , or by keypress. Having a time limited drift correct defeats its purpose. What happens after the timeout? Is the fixation accepted or not?
    Therefore, I'd suggest you add another pre-target fixation instead of hijacking the drift-correct. If this makes your trial sequence too long/slow. Take out the drift correct and make it only in the beginning of every block, or during another break.

    Does this make sense?

    Eduard

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