Dear Dr. Zalesky,

sorry my question was not really clear.
My doubts are more related to the difference between contrasts:

[0 0 0 1] vs [0 0 0 -1]

Since I'm testing for the interaction between treatment (placebo/drug) and condition (A/B) using t-test, depending from the contrast I will address only one-sided alternative hypothesis, likewise for the main effect.

So I was wondering what are the differences between the two contrasts, for the interaction? I mean by looking at my design matrix:


I would say that the first contrast (0 0 0 1) will test whether connectivity is increased in the placebo_A and drug_B conditions, while the negative contrast (0 0 0 -1) will test for an increase in connectivity for placebo_B and drug_A condition. Is this correct?

Sincerly,

Davide