MWorks behavior when eyetracking is lost

Darren Seibert's Avatar

Darren Seibert

15 Oct, 2015 01:35 PM

Hi Chris,

Is there a way to prevent mworks from issuing rewards when eyetracking has been lost? What seems to happen is that when the monkey turns his head and eyelink no longer has a signal, the fixation location is placed somewhere near the center of the screen--sometimes this falls within the fixation window which means that rewards will be issued even when there is no fixation.

Is there a way to prevent this from happening or to change where the eye coordinates are placed when eyetracking is lost?

Thanks,
Darren

  1. Support Staff 1 Posted by Christopher Sta... on 15 Oct, 2015 03:46 PM

    Christopher Stawarz's Avatar

    Hi Darren,

    What seems to happen is that when the monkey turns his head and eyelink no longer has a signal, the fixation location is placed somewhere near the center of the screen

    I don't know why this is happening. If any data is missing in a message received from the EyeLink, then MWorks sets the corresponding variables to -32768, so that's what you should see in your "raw" x/y eye positions. Instead, it sounds like the raw positions are being set to zero, which leads to the calibrated position lying near the center of the screen.

    Can you check whether that's correct (either by looking at the raw positions in your event file, or by watching on the EyeLink computer to see what happens when the monkey turns his head)? If it's true that the EyeLink sends zeros when the monkey is looking away, then you could use that fact to prevent rewards from being issued in that case. For example, you could attach an action to your raw y position variable that checks if x and y are both exactly zero. If they are, you could set a "no rewards" variable to one, and then check that before dispensing a reward.

    Chris

  2. Support Staff 2 Posted by Christopher Sta... on 01 Dec, 2015 01:31 PM

    Christopher Stawarz's Avatar

    Hi Darren,

    Just following up on this issue. Were you able to resolve the problem, or do you need more assistance?

    Thanks,
    Chris

  3. 3 Posted by Darren Seibert on 01 Dec, 2015 07:06 PM

    Darren Seibert's Avatar

    Hi Chris,

    Thanks for following up. The issue basically went away on its own so I
    never got around to implementing your suggestions. (We've moved the
    eyetracker and adjusted various other settings for unrelated reasons and
    the default location it places the fixation point now when tracking is lost
    is no longer near the center of the screen)

  4. Christopher Stawarz closed this discussion on 01 Dec, 2015 08:22 PM.

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