Hi all, 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). Contrast 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 may be considered multisensory areas, in order to restrict the following contrasts between multisensory modalities to multisensory ROIs, under two other different conditions. We define the ROIs with an F-contrast to which we apply an exclusive mask from 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 from this T-contrast: -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, Noelia