randomization of pairing with stimulus list


I have an experiment with pairings of two pictures and the pictures are in several stimulus list. I use two stimulus lists per trial to do my pairing, with the exact same number of pictures in each list.

I have several different trial, so I checked “Randomize the trials in the block” to randomize my trials, but i want my pairing be randomized too, and I need this randomization different for each participant. Now, Superlab just does A1-B1, A2-B2, … each time.

I have about 1000 pairings to present for each participant, so I can’t do it manually. I would really appreciate if someone has a simple or even a complex solution to do this randomization of pairing…


There isn’t a simple way to do this, but depending on your requirements, there may be a complex way to do it.

Please describe the pairings that you need. Are you wanting to pair a single item from A with a single item from B such that those two items will never show up again, or are you wanting to pair every item from A with every item from B?

I want to create pairings such as an item from A paired with an item from B, without consideration as to which items have already been presented. So the items can be repeated.
However I do not want every item from A to be paired with every item from B. For that, I thought of using the “expression editor” and telling superlab to present the trial for example 50 times.

Hank, is there a way do to the randomization with this sort of pairings ?

SuperLab doesn’t have a an automatic feature to do this, but you can pull it off by taking advantage of features not intended for this. The specific feature is “Expand Events that Use Lists.”

Basically, you’ll set up your experiment as you would normally set up an experiment using stimulus lists, and you’ll set up your two events. The one exception here is that only one of the two will use a stimulus list (say, stim list A). At this point you’ll “Expand Events That Use Lists.” This will open a new copy of your experiment with all items of “stim list A” expanded into multiple events. The other event that should use “stim list B” will should now be set to actually use the stimulus list.

At this point, every item within “stim list A” will be paired independently with each item in “stim list B.”

To limit this to a random subset, go into the block editor and tell it to randomize trials within the block. Also, in the “When to Run” tab, you should configure it to Present the Trials in this block while the expression is true, evaluated after each trial is presented, with the expression being “Number of Trials Presented in This Block Is Less Than 50 trials.”

That’s the quick overview. If you need more detail or if any of that didn’t make sense, let my know.

determin different responses for an event

Thanks for your answer.
I now have a problem determining the correct response for my pairings, because each stimulus list is used for several trials and for certains trials the correct response is “yes” and for others it’s “no”.
I organized my trials according to the correct response of the pairing. Therefore, if i was able to use the code values in trials to select the correct response, I would not have any problem.
However I understand SuperLab is only able to determine the correct response based on an event’s code value, and not based on a trial.
Is there a solution for this?