Hello SPMers-
I'm using a self-paced event-related design where the stimulus offsets are controlled by the
subjects responses. There are differences in reaction times between different conditions which
are typically on the order of 1-2 seconds, but occasionally as large as 3 seconds. There is also
varability with a condition for the stimulus duration, typically on the order of 1 second.
My understanding is that modeling the durations models different "heights" for the hemodynamic
response. Is this correct? If so, does this work within a condition, between conditions, or both? Is
this recommended?
Also, my reading of the dispersion derivative is that this accounts for differences in the width/
length of the hemodynamic response. Is this something I should use with my reaction time
differences? or will it remove differences between conditions that might be meaningful?
Thank you in advance,
Elizabeth
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