Study Design - Multiple conditions


I have a question regarding a study design. I would like to study inter-limb coordination using time-frequency plots in two different groups. My task would ideally consist of 9 different inter-limb movements (e.g., left hand, right hand = condition 1, left hand, right hand, left leg = condition 2,…). My goal is to assess if inter-limb coordination differs in both groups, and if this difference is more distinct in more difficult tasks. However, in a video of the new ANTS series, it is briefly mentioned that a study task of approximatly 7 tasks should ideally be avoided. The reason for this is not adressed. Could somebody explain why this is the case?

Moreover, if it were to be a problem, I could easily decrease the amount of conditions thar are present by only leaving one condition per limb condition in the design (e.g., only having one three limb condition instead of having all possible three limb conditions). However, I feel like this would make the task to easy and subjects would be able to ‘learn’ what set of conditions to expect.

Thanks in advance
Have a nice day

Hi Sybren. Can you tell me where I say that a design with ~7 tasks should be avoided? Perhaps I misspoke or perhaps there is some broader context there.

There’s nothing wrong with a richer experiment design. The typical permutation testing framework is designed for 2 conditions, so perhaps that’s what I was referring to. In your case, it sounds like the best approach will be to define time-frequency regions and then extract the data to run ANOVAs.

It is, of course, really good to think about how you will run the stats before collecting the data. But I don’t think you should simplify your experiment design simply to have 2 conditions for map-wise permutation testing.