Dear SPM experts,
I am a beginner in SPM. I analyzed my dataset using full factorial design (2X2 between subjects). For the final step "Results", after selecting the SPM.mat file, the system automatically generates 8 contrasts as following:
001{F}: Average effect of condition
002{F}:Main effect of A
003{F}:Main effect of B
004{F}:Interaction: A×B
005{T}: Positive effect of condition_1
006{T}: Positive effect of A_1
007{T}: Positive effect of B_1
008{T}: Positive Interaction: A×B_1
I compared the F contrasts and the T contrasts through xjview, and found there are some differences. For example, I can see a few activated regions in 008{T}: Positive Interaction: A×B_1, but none in 004{F}:Interaction: A×B. My question is how to interpret the results? Which, {F} or {T}, should I report? In addition, I couldn't understand what is the average/positive effect of condition as I saw the whole brain activated for both 001{F} and 005{T}. I'm very confused at this point and any reply will be greatly appreciated!
Thanks a lot for your help in advance.
Regards,
Shuran
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