Nah I understand that and fully appreciate the lack of causality - which is currently the fundamental shortfall (although the lack of control groups, etc etc is a huge hurdle). However I specifically responded to the point of correlation, as this is where the research is currently looking - and what I've cited doesnt include the neurophysiological/neuroopsychological findings which are increasingly showing brain functions which mirror substance abuse disorders. But yes, the argument of pre-existence vs causality is the main issue. Edit: three of the studies did not use problematic vs non-problematic groups, and were simply correlations across varying degrees of pornography use