Various duration in psychopy

I have an experimentation of n-back.

I have letter that appear for a maximum of 2.5 sec and then a fixation cross for 0.5 sec.

Right now: When the participant pressed on the keyboard, it ends the routine and go directly to the fixation cross. I have 60 letters so the experimentation would take at max 3 minutes, but it can be less if the participant pressed fast.

What I want : My experimentation should take 3 min at every time. So the fixation cross should stay for more than 0.5 sec if the participant answer fast

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Do you have an idea how to do that ?

I was thinking about creating a variable that equals 3. And then if text is 2 sec then 3-2 = 1 so fixation would be 1 sec, but I was not able to write that in my code component


1 answer

  • answered 2018-01-13 22:27 Jonas Lindeløv

    In your 'trial' routine, I would record the routine starting time. Then in the 'fixation' routine, I would wait until 3 secs have passed since that starting time.

    So in 'trial' routine --> Code Component --> 'begin trial' tab:

    trial_start = core.monotonicClock.getTime()

    Then in the 'fixation' routine --> fixation cross component --> duration, enter:

    $trial_start + 3 - core.monotonicClock.getTime()  # 3 secs later