Question about recording timing of keypresses

Darvas Máté · February 2018

Dear all,

I’ve been using Opensesame for some months now and I really like it. I have tried to create an experiment with it it and it worked pretty well, but I found a problem that I can’t solve.

In my experiment I would like to use stimuli (sentences) to which the participants can decide whether those are correct or incorrect by pressing different keys (e.g. "y", "n") . When these keys are pressed, the participant will get the next stimulus. However, I also would like that the program accepts a third keypress (e.g. "t") and measures its timing but I don’t want the program to present the next stimulus when this third key is pressed.

As far as I understand now if I don’t make “t” to be a possible response, than the program will not record the press of the “t” key. But if "t" is a possible response key, the program will automatically present the next stimulus when the key is pressed.
So my question is the following: how can I make the program record the “t” key without it presenting the next stimulus while other keys ("y","n") remain "regular" response keys?

Thanks in advance for the help!

eduard · February 2018

Hi Darvas,

You have two options here.

1) Set the run_if field of the next stimulus to [response] != 't'
However, this only works if the next stimulus that you refer to, is not the next trial, but just another stimulus in the current trial_sequence.

2) Use inline_scripting

kb = keyboard(keylist = ['y','n','t'])
key, time = kb.get_key()
if key in ['y','n']:
    # do stuff to present next stimulus

Hope this helps.

Eduard

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