Dear SPMers,

I have ran an fMRI experiment that consisted in a 2 (Factor 1= conditions F1A & F1B) by 2 (Factor 2 = conditions F2A & F2B) by 2 (Factor 3 = conditions F3A & F3B) factorial design. Data were acquired in two runs (run 1 and run 2).

For Factor 1 and Factor 2, conditions were equally distributed in the two runs (50% of conditions F1A, F1B, F2A and F2B in run 1 and the other 50% in run 2). However, for Factor 3, all the stimuli for one condition were gathered in one unique run (e.g. 100% of condition F3A in run 1) and all the stimuli of the other condition were gathered in the other run (e.g. 100% of condition F3B in run 2).

I have not managed to specify this factorial design in SPM8. It seems that SPM8 always assumes that all conditions are distributed in all the runs and as a consequence I could not manage to specify Factor 3.

Does anyone have an idea of how to do it, if it is possible?

Thanks in advance,

Gaya