Randomize stimulus lists without replacement?


Many thanks for all your help with my tasks!

Is there a way to tell Superlab to randomly pick from a stimulus list, but not to pick the same picture more than once during an experiment run? there is an option like this for

My task repeats the same trial several times, and is built off the backend you showed me for this task: http://community.cedrus.com/showthread.php?t=2045

Instead of letters, each trial is associated with an event that has a unique stimulus list (~20 pictures of a particular kind of animal). Each time the trial is presented, I would like Superlab to show a picture that it has not shown already this experiment run.

Thanks in advance!

This is easily done in the Trial Editor’s When to Run tab, like this:

Translated into English, SuperLab will only present a trial that has not been presented yet.

Thanks for the reply. Our task repeats each individual trial several times (it is based on the one you created that randomly selects a subset of trials for each ‘round’).

By necessity, the same trial will be repeated many times. Each trial has a unique stimulus list associated with it. For example, Trial 1 is linked to an event with a stimulus list containing a bunch of pictures of lions. Trial 2 presents a picture of a walrus from a stimulus list of several walrus pictures, etc. I am looking for a way to make sure that once each picture is presented, it is not presented again.


It would help if I can see the experiment. If you can, please post along with a note on which specific trial I should be looking at.

Apologies for the delay … I usually get an email when a new reply is posted but didn’t this time.

The experiment is attached. It’s based on the other task you helped me build. In this task, Superlab presents between 3 and 6 animal pictures per trial that the subject. the subject clicks a button on screen to ID the name of the animal (e.g., lion, walrus). Then, the subject sees a sentence and clicks a button to say whether the sentence is true or false. After 3-6 animals/sentences, it asks the subject to recall all of the animals they saw that trial.

The sentences pull from a stimulus list, and I can’t figure out how to tell Superlab not to repeat the same sentence after it’s been seen by the subject.

The animals also pull from stimulus lists (1 list per animal type), and again I don’t see how to keep Superlab from presenting a picture file that has been shown earlier in the task.


Animal Span.zip (83.8 MB)

I looked at the experiment but it is too large to figure things out by myself. Call me when you get a chance.