How do I get coder to show participants a random subset of all stimuli?

Coding
1

Hi all,
I have150 stims but want to show a given participant a random 75. How would I do this? The study is a simple stimulus rating task, I use a conditions csv file to store trial names and use trial handler to show participants the stimuli.
Thanks,
Richie

2

Depends what the stimuli are, words, pictures, shapes? For now, if you have a list of words e.g. words=[“duck”, “tree”, … “rock”, “cloud” ] you would just call numpy.random.shuffle(words) which shuffles the order 'in ‘place’ and then pick off the first 75 for a subject. When it is run for the next subject, a different ordering would occur. If you don’t want to disturb the words list, make a list of integers from 0 to 149, then shuffle this list and pull the items from the word list according to the first 75 numbers in the list of integers.

3

If using Builder, the easiest solution is simply to choose a loop type of random and then terminate the loop after 75 trials. This gives you your random subset of 75 conditions.

Insert a code component from the “custom” component panel, and in its “End routine” tab, put something like this:

if your_loop_name.thisN == 74: # the 75th trial counting from 0
    your_loop_name.finished = True