Dear SPMers,
I'm analyzing a blocked design fMRI task with three conditions (a, b, c). The blocks are seperated by a fixation cross which serves as a low-level baseline (bl).
My question:
Is there a difference in the analysis on the first level when I model the low-level baseline explicitely as a regressor?
That means: do the following contrasts differ?
a) explicit modelling of the baseline
regressors:
bl a b c
contrast: a > bl
-1 1 0 0
b) "implicit" baseline
regressors:
a b c
contrast a > implicit baseline
1 0 0
Thanks in advance & best regards,
Ben
|