answering anytime in the sequence

Raph · November 2015

Hi all!
I've set up a quick protocol that relies on an optical illusion due to the flickering of several images. Participants have to judge of the presence of the illusion.
To make the stimuli flicker, I made a sequence with 8 sketchpads (250ms each) in a loop (the variables of the loop modify the sketchpad at every trial), then fixation dot (0ms) with a keyboard response, then a logger. RT are not relevant, I just need the key pressed. So here, participants have to wait the end of the loop to give the response.

I want them to be able to give the response anytime during the sequence. How should I do ?

Thanks !

Josh · November 2015

Hi Raph, you could insert an inline_script at the beginning of your experiment with a line of code to initialize the keyboard: see http://osdoc.cogsci.nl/python/keyboard/ for instructions.

After your stimulus, you could insert another inline_script where you check by means of keyboard.flush() whether a key was pressed. If so, then that key will also have been logged in a keyboard_response variable. You may want to put the keyboard.flush() command in a while loop that goes on while keyboard.flush()==False:, so that participants really have to press a key for the trial to end. The while loop should be in the run-phase of your inline_script.

Cheers,

Josh

Raph · November 2015

Hi Josh, thank you for your quick answer.

Unfortunately, I am not very good with inline_scripts. I understand the logic on the keyboard.flush() and the while loop, but can you develop a bit on the way I should construct the while loop? Also, I'm not sure to understand where you would insert this script in the sequence, since I actually have several stimuli.

here's a screenshot,

Cheers,

Raph

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