Hi Esther A quick response to your last question: > Quickly with regard to the conditions: I want to use a factorial design, so > I believe I need to set up my conditions as indicated (6 total). > > The way I am doing this right now is as follows: I include the block onsets > together with event onsets in the same condition file, i.e., if one run has > two blocks and five events per block, the input would look like this: > > onsets: > 14 16 21 22 24 25 136 137 145 149 150 158 > duration: > 30 0 0 0 0 0 30 0 0 0 0 0 The problem with this approach is that by including both the sustained and transient activity in the same condition, you make it impossible to separate the two effects. I think what you want, as Donald suggested, is 9 conditions: block 1 (duration of 30 sec) A in block 1 (duration of 0) B in block 1 block 2 (duration of 30 sec) A in block 2 B in block 2 etc. This should let you test for all of the main effects and interactions in your design. I wouldn't think you would need to worry about different shapes of HRF. If there is indeed sustained activity during these blocks, then I would think that the standard SPM convolution with the HRF would reflect this. If you did want to use different basis sets, I don't think there is a way to do this in the GUI; you would probably have to write some code to do this. Hope this helps, Jonathan