Dear SPMers,

I initially modeled a full factorial ANOVA and created a t-contrast that examined brain regions that had negative BOLD activity associated with all of the 6 events  in the design matrix. I simply entered a value of -1 for each of the 6 events. This worked fine.

I have since discovered that because I have a within-subject design, I should have used a flexible factorial ANOVA with the subject factor modeled as a main effect. However I have been unable to create the same contrast. I tried to follow the Glascher & Gitelman tutorial and used the following contrast to test for 6 single regressors (subjs N= 18);  ones (1,18)*[6/18] -1 -1 -1 -1 -1 -1

I also tried zeros(1,18) -1 -1 -1 -1 -1 -1   But for both of these I got an error saying invalid contrast.

I assume I should be able to create the same contrast in the flexible factorial model if it worked for the full factorial.

Many thanks for your advice,

Nicky Kochan

PhD student

School of Psychiatry, University of New South Wales