Hi lz,

If the events are 10s and 4s long, the GAM functions will
do a very poor job of modeling them (unless you use a
boxcar-convolved version of GAM). So your basis functions
should be either:

GAM(8.6,0.547,10) and GAM(8.6,0.547,4)
or
BLOCK(10) and BLOCK(4)

or maybe UBLOCK instead of BLOCK

or, if question and answer are never compared, it would
be fine to use BLOCK(10,1) and BLOCK(4,1).


It seems like many options, but if question and answer
are never compared, the BLOCK functions would all lead
to identical group stats, with only a different scaling
of the betas.


The I would say not to use TENT, but to replace GAM with
something more appropriate. TENT would be more work,
and would only be appropriate if you expect shape differences
across subjects or the brain (or if these basis functions should
fail to model the main response, too).

- rick