I have a doubt about orthogonal masking to define ROI's analysis.
We are working on a un multisensory study. The task present two unimodal
conditions, one multisensory condition and a baseline (black screen).
images are brought from FFX to RFX analysis contrasting each stimulation
condition vs. baseline.
First, we want to remove global deactivations, from those areas which
considered multisensory areas, in order to restrict the following contrasts
between multisensory modalities to multisensory ROIs, under two other
We define the ROIs with an F-contrast to which we apply an exclusive
a T-contrast at RFX level, and we were wondering if then next two contrasts
fulfill the orthogonality criteria when applying masks:
First we define an F-contrast (main effects) at the contrast manager:
1 0 0
0 1 0
0 0 1
and, second, we apply a exclusive mask to remove global deactivations
-1 -1 -1
From the resulting areas of activation we define a ROI.
We are wondering ... whether are these contrast right according to the
orthogonality criteria when applying masks?
Thanks in advance,