Dear SPMers

We are running an experiment that requires subjects to verbally report at the end of a session, rather than use a button-press.

We have three conditions: Task A (A), Task B (B), and rest (R).

The experiment is organised in six sessions, e.g,

R A; R B; R A; R B; R A; R B. (randomized across subjects)

I appreciate that it would have been better to have all conditions in each session,

but this would not allow us to properly address our specific aims.

I don't think we can contrast the main effects of interest at the first level, so

to examine the A v B conditions, would it be better to do this at the second level, i.e.,

using the A v R and B v R contrasts?

Regards - MFG