Sorry, I mean age as a quantitative variable. Really this question is about quantitative variables in general. If this were in R, I would would look for the interaction effects Age : Emotion using lmer so see how a unit increase in age predicts the DV on an emotional face relative to a baseline face.
In afni I know how to find an interaction of emotional face type by age as a quantitative variable but I cannot find the direction of magnitude of that change based.
Does that clarify the question?
Thank you
