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Dear SPMers, I have a naive question that I wanna clarify. Suppose I have a fMRI experiment with 3 different conditions, conditions A, B, & C. Conditions A, B were our main interest but condition C act as a loose baseline. In SPM results, if I define a t-contrast (A - B), is it the same as [(A - C) - (B - C)]? Mathematically these two looks the same, but is it true, and why? If I really wanna do [(A - C) - (B - C)], shall I use an F-contrast, or is it unnecessary? Looking forward to your valuable advices. Regards, Kenneth Yuen University of Hong Kong