Dear Ben > Dear SPMers, > I want to extract data which reflects the mean level of activity in > a predefined > ROI. The aim is to correlate the individual mean activity during an > fMRI memory > paradigm with other subject characteristics. I have computed the individual > first level contrasts (active – rest / block design). > My question: which images should be used for extracting the average activity > in the ROIs? cons, betas or spmTmaps? this is reflected in your beta images (this is the 'activity' of each regressor) - the con images are simply the linear combination of the betas so if what you want is the 'activity' from a contrast you can either read the con images or combine results from the betas :-) .. as for how to extract data may I suggest EasyROI from my own website .. Best Cyril http://www.sbirc.ed.ac.uk/cyril -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.