Dear Alfonso and CONN community,

I have what may be a basic mathematical question. If I use a weighted GLM, how do I interpret the different FC results I get if I specify task conditions separately in the Setup tab compared to combining their onset times into one task condition?

For example, I have 3 conditions: Task 1, Task 2, and Fixation (i.e. an explicit baseline). On one hand I can set Tasks 1 and 2 their own separate condition, run CONN through Denoising, First-Level, then at the Second-Level I specify a contrast of Task 1 & Task 2 vs. Fixation [0.5 0.5 -1] to calculate the connectivity. On the other hand, I can choose to combine Task 1 and 2 for one TASK condition in the Setup tab, run the Denoising and First-Level, then at the Second-Level I specify a contrast of TASK vs. Fixation [1 -1].

The differences are subtle, but there nonetheless. I am not sure how to interpret it.

Best,
Lillian