Men worry far more than women about penis size, according to Veale and his colleagues. One study, published in April in the journal Proceedings of the National Academy of Sciences, found that women preferred larger penises only up to a point (anything bigger than a flaccid length of 2.99 inches (7.59 centimeters) did not additionally impress women), and preferences also varied based on a guy’s height. A 2012 study published in the Journal of Sexual Medicine found similarly ambivalent female preferences. In that study, women who experienced frequent vaginal orgasms were much more likely than other women to express an interest in better-endowed guys. For women who didn’t prefer vaginal orgasms, penis size was a far less pressing matter.

Nevertheless, men continue to fret over the size of their penises, listing it among their top body concerns along with height and weight, according to a 2008 study in the Journal of Health Psychology. Veale and his colleagues wanted to quantify that anxiety — an important step toward being able to evaluate psychological treatments designed to boost guys’ self-image.