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Dear SPM experts, Question from a newbie: I have a 2 x 2 within-subject design (task, control) x (2, 4 words), modeled in a flex factorial design using SPM5. I want to run the following contrast: (task:4 words - control:4 words) > (task:2 words - control:2 words). That is, I want to find increased task-related activity with the respective control conditions subtracted out. How would one go about this? Would I compute each individual contrast at the 2nd level, save the image files, and then use imcalc to compare them? If so, what operation should be inputted, and what p values/multiple comparison corrections for each contrast are appropriate? Many thanks, Kris