Sex at Dawn

Exploring the evolutionary origins of modern sexuality.

Christopher Ryan, Ph.D. is co-author of Sex at Dawn: The Prehistoric Origins of Modern Sexuality (HarperCollins 2010). See full bio

April 29, 2009, Sex

Mysteries of Masturbation

When it comes to sex, careful how you ask.

This post is a response to How Common Is Masturbation, Really? by Michael Castleman

Fellow PT blogger Michael Castleman recently raised the question of how common masturbation really is. He cited a study that seems to show it's less prevalent than conventionally thought. In the study, people were asked, in person, about their auto-erotic habits. Castleman acknowledges that this might be a bit awkward, writing, "It's possible that the face-to-face format suppressed response. Some people might not have admitted masturbating to an interviewer. But even allowing for this possibility, it seems clear that masturbation is by no means as prevalent … as many people believe."

There's good reason to believe Castleman may well be underestimating the importance of this very weak point in the study he cites.

One of the long-standing mysteries of human sexuality has been that heterosexual men tend to report having more sexual encounters and partners than heterosexual women – a mathematical impossibility. This was chalked up to men’s tendency to exaggerate upward and women’s to exaggerate downward in recalling such information. Psychologists Terri Fisher and Michele Alexander decided to take a closer look at people’s claims regarding age of first sexual experience, number of partners, and frequency of sexual encounters. Fisher and Alexander set up three different testing conditions:

1.    Where subjects were led to believe their answers might be seen by the researchers, who waited just outside the room;
2.    Where the subjects could answer the questions privately and anonymously;
3.    Where the subjects had electrodes placed on their hand, arm, and neck – believing themselves (falsely) to be hooked up to a polygraph that would detect lies.

Women who thought their answers might be seen reported an average of 2.6 sexual partners (all the subjects were college students younger than 25). Those who thought their answers were anonymous reported 3.4 partners, while those who thought their lies would be detected reported an average of 4.4 partners. While the women admitted to 70% more sexual partners when they thought they couldn’t fib, the men’s answers showed almost no variation.

Sex researchers, physicians, psychologists (and parents) must never forget that the answers you’re likely to get from women may depend very much on when, where, and how the question is asked, and who’s asking.