Pretty much anyone who’s seen naive or unsophisticated sex surveys knows that straight men consistently report far more sex than women, which is somewhat improbable given that it takes two people in most circumstances (and more in others, but we’ll leave those be for now). Or, as Michele G. Alexander and Terri D. Fisher put it, “Several of these well-established sex differences in sexual behavior are somewhat bewildering. Researchers have questioned the statistical improbability of men having more heterosexual intercourse partners than women, as these numbers should be equivalent for the sexes [. . .]”

They have an answer:

Men report more permissive sexual attitudes and behavior than do women. This experiment tested whether these differences might result from false accommodation to gender norms (distorted reporting consistent with gender stereotypes). Participants completed questionnaires under three conditions. Sex differences in self-reported sexual behavior were negligible in a bogus pipeline condition in which participants believed lying could be detected [meaning that “participants are attached to a non-functioning polygraph and are led to believe that dishonest answers given during an interview or on a survey can be detected by the machine” (28)], moderate in an anonymous condition [where participants don’t believe their answers will be revealed at all], and greatest in an exposure threat condition in which the experimenter could potentially view participants’ responses. This pattern was clearest for behaviors considered less acceptable for women than men (e.g., masturbation, exposure to hardcore & softcore erotica). Results suggest that some sex differences in self-reported sexual behavior reflect responses influenced by normative expectations for men and women.

The study is “Truth and Consequences: Using the Bogus Pipeline to Examine Sex Differences in Self-Reported Sexuality.”