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Trouble Recording Reaction Times

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  • Trouble Recording Reaction Times

    I am trying to put together a vigilance task where pictures flash rapidly on screen and participants have to press the space bar every time a target picture comes up. Ideally I want their reaction time for pressing the space bar after the target stimulus was presented so I can say that some pictures were identified faster than others.

    I have it set up okay as far as timing (I have the pictures and ISI's coming up as quickly as I'd like), but the reaction time data is always recorded as 0 on the results. I have all of my events set to record reaction time and I established that pressing the space bar is the correct response.

    Does anyone have any suggestions?

  • #2
    What input device are you using, e.g. keyboard or response pad?

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    • #3
      I'm having them use the keyboard (press space bar when the target appears).

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      • #4
        To elaborate a little bit more, every picture is displayed for 350ms followed by a 350 ms inter-stimulus interval. I have it set up so that every trial (in other words, the things in the trial column) is a picture followed by an ISI (so it is connected to 2 events). I am wondering if this is affecting my reaction time not being recorded since every time a new picture is displayed a new trial is beginning and Superlab automatically resets the reaction time at the start of a new trial.

        I am sometimes able to get it to record my reaction time if I am quick enough (if I press the space bar within the 350ms that the picture is displayed), but usually I (and I imagine most participants) end up pressing it during the ISI that immediately follows. Superlab does not seem to record my reaction time during the ISI no matter what I do (I tell it to record responses and reaction time; I tell it that pressing the space bar during the ISI constitiutes a correct response). The results acknowledge that I pressed the space bar during the presentation, but it always gives me a reaction time of 0.

        Any help is much appreciated.

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        • #5
          RTs will not be recorded during an ISI, but will be recorded during the event's time limit. It might be simpler to use an event of type Text and use that event's time limit as your ISI.

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