Hi,
There are a couple functions you might be interested in looking up, like sepWith or randomizeNoMoreThan, but both require specific labeling.
The way I understand your case, you have one block of undifferentiated trials in which you want to inject some other trials at regular intervals. This is definitely something you can do by coding your own function, the way I did for randomizeNoMoreThan above, once you’ve determined how frequently you want the catch trials to appear, and whether you want to re-use the same catch trial each time, or pre-generate multiple catch trials
Another method would be to modify the running order. PennController uses this method in a few cases, but hopefully that shouldn’t create any conflicts
Jeremy