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Dear SPMers, I am confused with the function of the exclusive masking. I have 3 fmri sessions. Each has 3 conditions. Session A: Rest A1 A2 Session B: Rest B1 B2 Session C: Rest C1 C2 They are put into the same design matrix as A1 A2 B1 B2 C1 C2 for 1st level analysis. The rest conditions for all 3 sessions are left out. Basically A1 and A2 are the same visual stimuli and the only difference is the stimulus for A1 is moving to the right and for A2 is moving to the left. It is the same for sessions B and C. A B and C are different visual stimuli. The contrasts are definded as follows: 1 1 0 0 0 0 to look at A 0 0 1 1 0 0 to look at B 0 0 0 0 1 1 to look at C I would like to find the common and different areas that all 3 sessions are activated. I use the aal toolbox. For the common areas: I use the function conjunction. And so far so good. BUT,....For the different areas: When I look at all sessions separately, ie comparing the activation areas manually, table by table, it is different from if I mask them with exclusively as A exl (B and C). eg. It reported the areas that are commonly activated in A B and C also. I am not cleared that should I use exclusive masking or should I just compare tables? Any comment would be appreciated. Thanks in advance. best regards caroline