> after I add the demeaned data into the table, I don't need to use the qVarCenters option, right?
Right. Or you could simply set it as 'qVarCenters 0'.
> Should I be interested in comparing A1vsB2 and B1vsA2, how should I proceed?
If those contrast make sense to you, do it with 3dttest++ as a two-sample t-test (the covariate can be added too).
> I am interested also in the conjunctions of the different conditions. In this case, how should I proceed?
> I guess I first need to get 4 contrasts between each condition and baseline (how?) and then perform
> the conjunction with the step function? Is that correct?
The conjunction among those 4 conditions? If so, what you're describing is the conventional approach, but personally I'm not a fan of dichotomization.
Gang
