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Dear All, yes I know this topic has come up before, but as I am writing a methods section it occurs to me that I am no longer clear on the appropriate way of applying post-thresholding contrast masking. The scenario is farily strightforward: I've got 3 EVs:C1=CondA v BaselineC2=CondB v BaselineC3=C1>C2 Now, to avoid reverse activations I'd like to use contrast masking on C3. However:if I only mask it with C1 (Z>0) then I could get voxels active because they are Z=0.00001 in C1, but Z=-10 in C2, so no good.If I only mask with C2 (Z>0) then I could lose voxels that might be Z=10 in C1, but happen to be negative in C2, even by just very little, so also no good.If I mask with C1 AND C2 (both Z>0) then it means that I'm only looking at voxels which have Z>0 for BOTH conditions, so if a voxel has Z=10 in C1, but Z=-0.000001 in C2 I would lose that voxel, which is also no good! For this reason, I am having a hard time justifying any of these three approaches in my methods section. Is there a proper way to use this tool to avoid getting reverse activations without losing voxels? Cheers R