randomize items in a stim list?

SuperLab SuperLab 4 Support
1

I just figured out how to use stim list (awesome feature!). Is there a way to randomized items within a stim list?

2

Technically, no, but this is really a multi-part answer.

  1. Currently, stimulus list items cannot be randomized. This is only relevant if you are using more than one stimulus list in a given trial. If you are using multiple lists, the first item in list A will always be paired with the first item in list B. If you have lists of different sizes, it will look like this:

A1 - B1
A2 - B2
A3 - B3
A4 - B1
A5 - B2

given that list A has five items and list B has three.

  1. You can simulate the appearance of randomized stimulus lists simply by randomizing trials within a block. For each trial with an event using a stimulus list, a new trial is created at runtime with one stimulus from that list. After these trials are created, they can be randomized within the block. Therefore, if you have multiple trials in one block using multiple stimulus lists, and then you randomize the trials, you will see the various trials randomized within each other, as they are randomized after they are created.

I hope this helps!

3

Thanks for the reply but it does not really help. When I want an experiment that presents a list of items I usually have it randomize the order. The stim list allows me to make a one trial experiment but now randomizing is gone so I must go back to one trial per item, defeating the purpose of the stim list. In the future a random option for a stim list would be VERY helpful.

4

I think you may have missed the importance of item no. 2 above. If you randomize trials in the block, you are effectively randomizing your stimulus list items. The only way this doesn’t help is if you are using more than one stimulus list within a single trial, which is what item no. 1 discussed.

We do have upgrades in mind for stimulus lists, though, and your input is appreciated.

5

Maybe I’m confused but if I randomize the events in a trial it also randomizes the events before and after the stimulus list, not just the list. Thus, a fixation cue will sometimes come before the stimulus and sometimes after, which is no good.

6

yes, I was confused. I was trying to randomized the events not the trials. It works fine with random trials. :slight_smile: