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Recording RT from button release?

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  • Recording RT from button release?

    Is it possible to record reaction time from the release of a button to the depression of another button in SuperLab? Seems like it is capable of a response consisting of being released, but I can't seem to get it to work.

  • #2
    Button press/release elapsed time across trials

    I'm not sure exactly where in this process you actually begin to encounter difficulty or confusion.

    It looks like you found the option for whether or not to record key release. That will be crucial.

    Just in case you did not find it, that is here:

    http://i53.tinypic.com/1zbywxu.png

    After double-checking the "Options" tab on that RB input settings window (the window shown in the link), then also go to the "Data to save" tab (right next to the Options tab), and make sure that you save "Whether the key was pressed or released."

    After that, the output data should naturally look something like what is shown here:

    http://i52.tinypic.com/212wwfc.png

    The output shown in that link clearly recorded multiple key press and key release actions during one single SuperLab event.

    The reaction time column is showing the running milliseconds-elapsed count since the start of the trial. Therefore, by taking the millisecond value at the *release* action and subtracting the millisecond value at the immediately preceding *press* action for that button, you can calculate the milliseconds that passed between the press and the release.

    The same could be done for calculating the time between a release and a subsequent press.

    Ahhh...... ah ha!

    It just occurred to me that getting the time ACROSS TRIALS is probably the sticking point.

    If that is true, then you will most likely want to do the following:

    http://screencast.com/t/uhwWI8iOZk

    Experiment >> Options >> Columns to save >> Cumulative Time

    After that, there is a column in the output named "Cumulative Time". You can see (from the link below) that the Reaction Time column will not be helpful for calculating the lapse between button actions ACROSS trials, because the reaction time is a reaction time _within_ an event, and is reset to 0 when the new trial starts. However, the "Cumulative Time" column will allow you to do the same subtraction calculation that I mentioned earlier:

    http://i53.tinypic.com/a2b1mo.png

    You might notice in that screenshot that "Cumulative Time" is running 95 milliseconds ahead of (further in the future than) the reaction time column. That is because the experiment was apparently loading for 95 milliseconds before the start of the first event of the very first trial. But other than that, you can see that Cumulative Time and Reaction Time are marking the same time -- with the principal difference being that Reaction Time is getting reset at the start of each new trial, whereas Cumulative Time is never reset.

    Did that help? Hoping so!

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    • #3
      Thanks for that! That was very detailed and I really appreciate it. I did have all those options checked though, so I'm not sure what is wrong. I am about to create a very simple experiment from scratch to test this again.

      I found an old thread that looks like the person was trying to do the same experiment than me. The only difference is that I do not require Evt3 and Evt 4. Is there an easier way of dealing with the problem posed by bweaver in this thread? Thanks again

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      • #4
        Sorry - the thread is

        http://community.cedrus.com/archive/...php/t-419.html

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        • #5
          Problem solved for now in terms of the key release not working! Thanks so much.

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