afni.nimh.nih.gov

Ekarin,

Since all the three predictors are between-subject quantitative variables, I suggest that you do the following:

1) center each of the three variables properly (e.g., around their mean)

2) create four new variables - one for each interaction - and label them

3) perform a multiple regression analysis on the seven variables with, for example, 3dttest++ or 3dMEMA

Gang