Dear Oliver,
> > I suspect that you have modeled a constant term at the second level (which
> > should be omitted).
>
> I am afraid I did not understand your answer exactly. I repeated the
> analysis with 22 contrast images representing two simple main effects
> (-1 1 0 0 and 0 0 -1 1) in 11 subjects and omitted all that I could
> (incl. global normalisation etc.). I entered two covariates, one for
> each main effect, i.e.
>
> 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 and
>
> 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1.
>
> Still, it was impossible to enter a contrast like [1 0]. Where went I
> wrong? Or: how can I omit the possibly automatic (?) modelling of an
> additional constant term (I could not find anything in the defaults
> section)?
Your approach is absolutely right but I am not not sure if you have
modelled the constant or not (your design matrix at the second level
should have just 2 columns). I would use basic designs to specify you
simple model.
All the best - Karl
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