Hi Rick,
Thank you for your answer; it was helpful. It sounds like unless I have hypotheses that the duration of my stimuli would impact the amplitude of the BOLD response, it may be better to remove duration from the model, as the deconvolution TENT functions will account for narrower/wider HRF functions by nature of being data-driven (as opposed to a convolution, where I might want to include the duration even if I don't expect it to modulate amplitude).
Regarding the first 20 beta weights (0 - 19 in the initial question), can you please confirm that the unmodulated response is the overall response (aka the contribution from the modulators is included)? Or does the unmodulated response subtract the contributions from the modulators and provide the remaining mean response?
Many thanks.