Hi,

I performed first level PPI analyses for each of my participants using amygdala as seed region and conditioning effects as psychological variable (contrast: CS+ vs CS-). I then performed a group analysis and extracted a VOI in the ACC from the groupT-map, from which I created another physiological variable and performed 1st level PPI analysis in all participants with ACC as seed region. For each participant, I  created 4 PPIs (amygdala CS+, amygdala CS-, ACC CS+ and ACC CS- ) to plot the graphs showing the interaction between the physiological and psychological variables at the individual level and everything went well. 

I would now like to plot these PPI graphs at the group level, to see the interactions between these variables in the whole sample. I tried to adapt a first level batch script but I guess this is not the right way to do it as I always get the following error message:

??? Reference to non-existent field 'RT'.

Error in ==> spm_peb_ppi at 147
RT      = SPM.xY.RT;