Hi Mark,

The "-iresp k prefix" options are requesting IRF datasets.

If you open those datasets in afni, and look at them with
graph windows (to see the 15 values in the case of the
HowTo, for lags 0-14), paying particular attention to
voxels with significant activation (you could overlay an
F-statistic in color, as a guide), it will give you a good
idea of what the response was for each voxel, and for
each particular condition.

The mean signal change is just those numbers averaged
(but not over all 15 lags).

This is explained and illustrated in the HowTo by Peggy,
in section H of AFNI_howto_subject, at
[afni.nimh.nih.gov] .

Please let us know if that description is not clear enough.

- rick