Hi, I'm wondering how to code general linear trends within 3dMVM (or another program if there's a better one) as a function of a quantitative variable. For example if people are looking at afraid and calm faces across a developmental population, and I want to see if the difference in activation between afraid and calm faces changes as a function of age, how would I code that? My understanding would be something like 'Emotion : 1*Afraid -1*Calm Age : ' would only look at that difference at the mean centered age, but not across age groups.

If there is another program that would be good for this too, that would be very helpful.

Thank you!
Michael