I’ve been looking at the ideal functions resulting from 3dDeconolve, and was quite puzzled at the length of each trial.
Here is an example:
3dDeconvolve -nodata 195 2.0 -num_stimts 1 -polort 3 -x1D example-X.xmat.1D
-stim_times 1 ‘1D:112 168 322’ ‘BLOCK(14)’
Now, the TR here is 2. Since the X.xmat.1D files are in TR’s, I expected to see a convolved response function with length of 8 to maybe 9 TR’s. But in my X.xmat.1D file, I noticed the 1st trial is roughly 15 TR’s long. Equating to about 30 seconds. Practically double the stimulus duration.
What is the case?
Any help would greatly be appreciated.