Dear SPM experts,
Suppose I have 3 trial types. That is, in shape (S) trials, subjects have to answer the shape of the stimulus object; in number (N) trials, subjects have to answer the number of the stimulus object; in control (C) trials, subjects just have to do a press response when they see the stimulus object. Considering fMRI data analysis, where we will analyze contrasts of "S>C," "N>C," and "S>N," is it a must that all the three trial types should have the same number of repetitions? Is it ok if I have 40 repetitions for S, 40 repetitions for N, but only 20 repetitions for C? Thanks. Mike
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