Irene,

If 'Corr' is a within-subject quantitative variable, consider

-ranEff '~1+Corr' \

> If I understand correctly the glt4 contrast compares the beta-covariate correlation between groups.

More accurately, GLT #4 looks for the difference of association between beta and 'Corr' between the two group when Category is fixed at 'iaps'.

> When I pulled the betas from the significant cluster and run the correlation analysis in SPSS there
> were no significant correlations for either groups. Could you help me understand why?

I'm not familiar with SPSS. If 'Corr' is a within-subject quantitative variable, how do you handle it in SPSS? You may try to extract one voxel, and try it in SPSS and see if you can duplicate the result from 3dLME.

For your 3dMVM script: change

-num_glt 3 \

to

-num_glt 1 \

Gang