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Can I get both key release AND key press times for an event?

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  • Can I get both key release AND key press times for an event?

    Hello group. I've noticed that there are some threads that discuss using both key release and key presses. I didn't find anything that answered my question directly though. I want to present a series of events as follows:

    Evt1 - Press & hold HOME key --> wait for home key depression
    Evt2 - Fixation cross (variable interval, no response, subject still holding down home key)
    Evt3 - Cue (fixed duration, no response, S still holding down home key)
    Evt4 - Fixation cross (fixed duration, no response, S still holding down home key)
    Evt5 - Target (on until response OR some duration)

    I would like to:

    1) Ensure that the home key is held down during events 2-4
    2) Get the time from the onset of event 5 to RELEASE of the home key
    3) Get the time from the release of the home key to depression of the target key

    For point 3, the time from the onset of event 5 to depression of the target key would also work.

    From some of the other threads I read, I wonder if I have to create Evt5a and Evt5b (with identical displays), and take the key release time from 5a and the key press time from 5b. Any pointers would be appreciated.

    By the way, the point of this is to decompose overall response time into decision time and movement time.

    Thanks,
    Bruce

  • #2
    Hi Bruce,

    1) Ensure that the home key is held down during events 2-4
    2) Get the time from the onset of event 5 to RELEASE of the home key
    3) Get the time from the release of the home key to depression of the target key
    For 1), you can do it by having the events end on a correct response or time limit, with the correct response being set to None, the participant must not respond. This is set in the Event Editor's Correct Response tab. If they do release the key, you can then provide a feedback that reminds them that they shouldn't, and then repeat the trial.

    For 2), this is easily accomplished in the Event Editor's Input tab. For event 5, turn On the Reset RT Timer checkbox.

    For 3), you're onto something with your idea about creating Evt5a and Evt5b, except that it's a little simpler: Evt5b does not have to be a second display. Simply make it an event of type Text that doesn't actually display anything, and then set it up so that it doesn't erase the screen.

    I hope this helps,

    Hisham.

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    • #3
      For 3), you're onto something with your idea about creating Evt5a and Evt5b, except that it's a little simpler: Evt5b does not have to be a second display. Simply make it an event of type Text that doesn't actually display anything, and then set it up so that it doesn't erase the screen.
      Nice one--I'd not thought of that. Thanks Hisham. I don't have time to work on that project right now, but will give this a try when I do go back to it.

      Cheers,
      Bruce

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