Thanks for the quick response, this is really helpful. If I understand correctly, you’re suggesting to specify both sessions for every participant, resulting in one design matrix. I could then specify the interaction contrast on the first level for every person, and test the interaction on the 2nd lvl with a one-sample t-test (e.g. 1 or -1) and include the covariate.
I do have one very basic question about the syntax for the contrast though, namely: in my example, which syntax do I use to set up an interaction term on the first level? In my understanding, -.5 5 -.5 5 would give me the main effect of condition, but I wouldn’t know how to specify the interaction term. In the past I have used paired samples t-test to circumvent exactly this issue.
Ing. Stijn Michielse MScRes
School for Mental Health and Neuroscience – Division Mental Health
Department of Psychiatry & Neuropsychology
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