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Dear users,

I have an fMRI event-related design with 6 conditions = 5 conditions of
interest + a baseline condition and an interstimulus interval, varied from
0.5 sec. to 1.5 sec. I want to model my design using the HRF.

My question is: what are the differences in case I model the baseline
condition in my design, and if I don't model the baseline condition in my
design?

As I understood,
1) if I do model my baseline condition, then my contrast will be (for
example condition1>baseline) defined in spm as [1 -1]. In this case the
baseline is different from zero.
2) if I do not model the baseline condition in the design, then this is set
to zero and my contrast should be (e.g. condition1) [1 0].

As I saw, the results of the main effect of condition1 do not differ between
the two designs. Is all this correct? Should I see/expect differences, and
if yes, why?

Thank you!

Best,
Ramona