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n-back and wrong keyboard response collection after changing OS


I have created a n-back test and I am pretty sure that collecting keyboard responses worked properly on OS 3.2.7 (Python 2.7). Now I am using OS 3.2.7 (Python 3.6) and something is wrong during response collection.

Usually you press a button (e.g. space), when there is a hit. When there is no hit, it is a correct response when you don't push a button (None).

Looking at my excel file, it seems like OS only counts "None" as a response (and/or space doesn't work). When I press space, although there was no hit (=wrong answer), it is still logged as a correct answer and when there is a hit and I do press space (=correct answer), it is logged as a wrong answer.

Does anyone have an idea?




  • Hey,

    I have found out that the error was due to my blankscreen, which was presented before the keyboard response and which had a duration of 1245 ms - during that time no keyboard responses could be collected.

    So for now, I have changed my blankscreen to 0 ms, so that the participant can still see the blankscreen, but OS already shifts to the keyboard_response (2500 ms). But now, Ihave the problem that when participants press the space bar (which is clearly below the timeout duration of 2500 ms), OS immediately continues with the next item.

    I mean this is correct by default, but is there a way to specifiy within the keyboard_response, that even when participants press a key, the program waits until the time is over?

    Best, Mad

  • Is it possible to put the keyboard_response at the beginning of the sequence? I have added an inline script like this

    but the output file contains only undefined answers, I guess somewhere I need to specify that the program uses the correct_response variable?

  • Hi,

    you can add an inline-Script (or an advanced delay) after the keyboard item, that waits for 2500 ms - response time (the variable is probably var.resp_time()), but you can check your logfile to be sure.

    Does that make sense?


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