The most glaringly obvious problem with this study is of course its cross-sectional methodology. It’s just as likely that men with less grey matter in their striatum are more attracted to porn, as opposed to porn causing that brain profile. The researchers know this. “It’s not clear … whether watching porn leads to brain changes or whether people born with certain brain types watch more porn,” Kühn told The Daily Telegraph (and yet that paper still ran the headline: “Watching pornography damages men’s brains”).

A further problem with correlational studies is not just that the causal direction can run either way, but that an unknown or uncontrolled third factor (and others) could be causally involved. In the case of this study, the elephant in the room is personality. Unsurprisingly, personality is linked with media use (including porn consumption) and with brain characteristics. Asking men how much porn they watch is a crude indicator of their extraversion, (lower) conscientiousness and desire for sensation seeking. For instance, men who watch porn in work hours tend to be less conscientious and more impulsive. Last year, a study reported: “Neuroticism, agreeableness, conscientiousness, and obsessional checking all significantly correlated with a latent measure of compulsive behavior upon which use of Internet pornography use also loaded.”