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Control duration of sketchpad

Hi all. I am doing a simple priming experiment in Open Sesame in which individuals are responding to a word following the prime given with the response time being recorded. As I went through my first round of data I saw some participants had response times of 0. Through some trials I believe that individuals are responding when shown the prime so the data I'm getting is showing that participants responded immediately.

Is there a way that I can control the duration of the sketchpad or ensure that data will not be logged if participants response time is zero?

Thanks in advance!


  • Hi,

    I think the problem is that you have set a duration for your sketchpad. If you want to measure response times from stimulus presentation, you have to set it to 0 and instead set the timeout value in the keyboard response item that follows to the duration you want to sketchpad to be on the screen.

    Does this make sense?


  • Hi,

    This does make sense, and I have done something very similar so I don't believe it will solve the problem. I believe participants are repeatedly clicking the mouse so fast (in hopes of getting through the study faster) that the program sees this as instantaneously answering when shown the target word. Is it possible to create something that would not allow a response if it is less than a certain amount of time?, For instance, >3 ms before a response is allowed which in turn would stop the hasty participants? Or is something like this impossible to fix? I have done something similar for when participants are responding too slow (they must respond within 800ms or feedback is given telling them they are too slow) but I'm not sure if this is possible to do if they are too fast.

    Thank you.

  • Well, the same logic can work in your advantage. If you set the duration of the sketchpad to some low value (say 20-30 ms) that this will be the quickest participant can get through the experiment. When then computing the response times, you shouldn't forget to add those 20-30 ms in the end.


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