Thanks, Rick. That makes sense, b/c my stimulus "on" period is > 1 TR, so there would be summation in the gamma wave output.

Now, here's my "real" question. I have used waver to create gamma waves for my different conditions, and then used these as the "stim_file"s for 3dDeconvolve. As part of pre-processing, the time series have been converted to % signal change, before performing 3dDeconvolve. I want my coefficient values to be "meaningful" (i.e. in terms of % signal change), so, isn't it necesarry for the stim_file to go from 0 to 1, in order for the coefficient to be in terms of % signal change?
If I am thinking of this correctly, I realize that I could just convert the stimulus coefficients (by dividing by the peak value that waver actually produces) post-hoc, but I just want to be sure that I am thinking about this correctly.

Thanks,
Liz