Hi Olga,
This design matrix may misbehave as it is rank-deficient: the sum of columns 2-4 is equivalent to column 1, and therefore there are an infinite number of solutions for the beta values. While the GLM code is designed to still work in such circumstances, and due to the nature of your intended contrasts it shouldn’t actually have an effect on your t-values, it’s nevertheless avoided as best practise.
You could simply omit the first column entirely:
1 0 0
1 0 0
0 1 0
0 1 0
0 0 1
0 0 1
(for two subjects in each group)
Moreover, while you have three groups in your experiment, none of your hypotheses actually require all three groups to be present in the model at the same time; and fixelcfestats can’t (currently) test more than one hypothesis at a time. So you could simply construct two separate design matrices: One for comparing T and D, one for comparing T and Dr; then run fixelcfestats separately for each.
Rob