HI Rick,

Thanks so much for your reply. My stimulus events lasts about 1.5s.

I was silly to think of using too many regressors. In my current model, there are 42 regressors (6 motion stimuli files are included). But now I meet a trouble, and can not find the way to correct it. It is very strange. I do not find any problem (script, also the time stimuli files), but the script can not go!

** ERROR: '-stim_base 13' illegal with '-stim_times'
** ERROR: '-stim_base 14' illegal with '-stim_times'
** ERROR: '-stim_base 15' illegal with '-stim_times'
** ERROR: '-stim_base 16' illegal with '-stim_times'
** ERROR: '-stim_base 17' illegal with '-stim_times'
** ERROR: '-stim_base 18' illegal with '-stim_times'
** FATAL ERROR: Can't continue after above problems!
** Program compile date = Aug 13 2014

Again, thank you very much. Rick