Hi Rick or Gang,

I couldn't find an answer to this specific question in the archives. I have gone through all the RSFgen steps and found the optimal sequence timing for my study. My issue is that the optimal sequences contain a few ISIs upwards of 30 seconds. This is presumably because there are only a few, long stimuli per run (20 seconds each). Thus, RSFgen ends up having large clumps of jitter especially if it puts some trials back-to-back.

Decreasing the *total* amount of jitter produces less optimal sequences (less power). The question I have is whether really long ISIs (longer than a return to baseline would take) make any psychological sense. Is there a reason why these long ISI's are, in fact, related optimally to power? The only thing I can think of is that sticking a couple of long ones in a run decreases expectancy effects and thus expectancy-related noise. Is RSFgen designed with such cognitive processes in mind? If BOLD is roughly constant after 20 seconds post stimulus, can I just shorten the long ISI's to that amount?

From previous (year old) posts it appears I can't specify a maximum ISI in RSFgen-- still true?

Thanks!
Thalia