Dear experts, dear community,

I was wondering what the general opinion is about modelling the durations of your conditions in an event-related experimental design.

From my understanding, you would – traditionally – not model the durations and use stick functions, at least that is what most tutorials/guides say that I found.

But I’ve seen it done differently a couple of times now, and it also seems sensible: you just give the model more information to work with by also modelling the durations.

I haven’t dug into the spm code yet, but I assume the functions used for modelling are the same no matter which duration is given as input, or does spm indeed do something categorically different in the case of a duration of 0?

My results vary considerably depending on whether I modelled the duration.

My experiment has events that are 1-3s long, with a SOA of 1-5s, I worked with SPM for the GLM.

Thanks a lot in advance!