Dear all
I have just tried to incorporate a parametric modulator (pmod) in my
model. Our task is repeated over several sessions and hence, to bring
results to the second level I normally collapse conditions (Con# ) over
sessions (S#) by creating a contrast like this:
S1 S2
Con1 pmod Con2 Con1 pmod Con2
1 0 0 1 0 0
So I have tried the same thing for parametric modulators, but SPM tells
me that the contrast is invalid.
S1 S2
Con1 pmod Con2 Con1 pmod Con2
0 1 0 0 1 0
I am sure there is a reason, can anyone explain it?
And what would be the proper approach to analyse the parametric
modulators over sessions?
Many thanks in advance
Cheers
Christoph
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