Simplest code to select random rows of two alternating excel files (avoiding delays along the experiment)

It does help a lot!

The cat and sel trials are very similar and I can use a single routine and loop for both.
So I am going to try and use your first approach, either using @wakecarter interleaved lists method, or another way to randomize lists and zip them in an alternating manner.

At this point, I wonder whether these methods can be applied in the second part of my experiment. The structure is the same (alternating 2 types of trials) but, instead of running all trials from the conditions file in a row, I need to run 8 intermixed trials of types A (cat) and B (sel), then 8 intermixed trials of types C (testcat) and D (testsel), then go back again to A and B…, and so on.

That is, I wonder whether I can “pause” the random presentation of conditions after 8 trials, and continue with the random list in the following 8-trials repetitions.

In case it helps, the following figure represents what I want to do in the whole experiment

Do you think that would be possible with either method?

Thanks again!

Paula.