Dear Pascal,

I have a question regarding a conjunction analysis.
I use SPM5 and I would like to do a RFX analysis of the conjunction of 4 conditions over 20 subjects.
So I would like to do a conjunction in each subject of the 4 conditions and than use this data of each
of the 20 subjects in a RFX analysis. Do I have to use a flexible factorial design ?  Any suggestions on
how to set this up ?

I do not think you can do a (RFX) t-test on a conjunction.  This is because a conjunction is , itself a
statistical test. In other words ,you would not test a contrast conjunctions but test for a conjunction of contrasts.

I suspect the best thing to do it to create 4 contrasts for each subject and analyze these 20 x 4
contrasts with an ANOVA at the second (between-subject) level. You could then perform a conjunction
over the 4 condition-specific contrasts?

I hope this helps - Karl