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Non repeated randomized stimuli


#1

WIN 10
PSY 1.90.1
Standard Standalone

So I am trying to insert a loop that presents 8 stimuli (stories) that should be randomized, but however they should not be repeated and each stimuli should be presented only once. I am finding that there is no option to have the stimuli be randomized without being repeated. Looking at other fourms I did see randomization of repeated trials but I don’t think that will be useful to create non repeated randomization. Is there any way to do so on the builder or does there need to be code that has to be inserted?


#2

I am not entirely sure what exactly you’d like to achieve. You have 8 different stories the order of which you would like to randomise. In addition, you would also like to make sure that every story is presented only once. However, it seems I’m misinterpreting something as there could be no repetitions under the conditions I just described. Could you perhaps clarify?

Jan


#3

So when creating a loop and conditions file that contains the 8 stories it is possible to randomize them, but I don’t think there is an option to randomize without an repetitions. As in the same story could come up twice and that is not something I want. I was wondering if there was an option to do so or if there wasn’t an option at all.


#4

Could you perhaps clarify exactly how many different stories you have, and how many trials? Alternatively, you could upload your experiment and input files.

Jan


#5

You’d like to shuffle the stories, right? Not randomly sample from them?


#6

Hi @j3rrin, are you using Builder or Coder? If Builder, then using a loop with the “random” option is what you want.

If the loop type is sequential then, on each iteration through the Routines, the next row will be selected in the order listed in the file. Under a random order, the next row will be selected at random (without replacement); it can only be selected again after all the other rows have also been selected. nReps determines how many repeats will be performed (for all conditions). The total number of trials will be the number of conditions (= number of rows in the file, not counting the header row) times the number of repetitions, nReps. With the fullRandom option, the entire list of trials including repetitions is used in random order, allowing the same item to appear potentially many times in a row, and to repeat without necessarily having done all of the other trials

Taken from here. If you are building your experiment in Coder, then it would be good to see your code.