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Something wrong with output RT's

Hi, I used open sesame to design my modified GO /No GO experiment for master thesis. It seemed to work but the out put RT's for most participants on certain trials seem absurd. I have attached a screen shot of the Excel form,RT's on Go condition are highlighted. As none of my lab members have worked with open sesame , I'm relying on the forum for some clues to fix this problem.

RT.PNG 38.7K

Comments

  • lvanderlindenlvanderlinden Posts: 292
    edited March 15

    Hi,

    The RTs of 1600 ms are from the trials on which the participant did not respond at all (see column CB in your output file) and therefore a timeout (that you probably set to 1600 ms in the keyboard_response item) occurred.

    The extremely fast RTs might arrive because you did not set the duration of the preceding sketchpad item to 0.

    Is this the case?

    Just let us know if this helped!

    Good luck!!

    Lotje

    Lotje van der Linden - http://www.cogsci.nl
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  • @Ivan I did set the sketch pad set to zero. But accidentally I kept the flush pending keypresses option off, do you think that could be reason for lot of zero RTs? I don't understand why though. Now I ran it again with flush pending keypresses option on, it doesn't give zero RTS but out of 700 trials there are four or five short RTs (less than 20) is it coz they are pressing the key in anticipation?

    P.S the trial structure of the experiment is there are s words appearing one after the other in different colors. Stimulus presentation is 400 ms and ISI is strictly 1600 ms. There are go and no conditions .

  • eduardeduard Posts: 815

    I kept the flush pending keypresses option off, do you think that could be reason for lot of zero RTs?

    That's exactly it. key presses that were pending from earlier, were triggering a response instantly when the experiment reached the keyboard_response item.

    700 trials there are four or five short RTs (less than 20) is it coz they are pressing the key in anticipation?

    Probably.

    Thanked by 1rampriya darshini
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