Hello!

I am a relatively new user of afni.proc.py and have a question about what regress_basis option that I should use for my analysis.

The fMRI data that I am analyzing is an event-related design memory task, which includes three types of events (i.e., negative rating, neutral rating, binding). For each type of event (e.g., negative rating), the duration is the same across the whole task (e.g., 2.5s) and across all the participants (the stimulus onset times are different across participants). Given this design, is it correct to use the "-regress_basis 'BLOCK(duration,1)" option? Any guidance would be greatly appreciated!!

The part of my afni.proc.py script for the first-level GLM analysis (including the -regress_basis part) is detailed below:
-regress_stim_times negative_rating.txt \
neutral_rating.txt \
binding.txt \
-regress_stim_labels negative_rating \
neutral_rating \
binding \
-regress_basis 'BLOCK(2.5,1)' \
'BLOCK(2.5,1)' \
'BLOCK(3,1)' \