Here’s a hint: the title of the new study by the National Campaign to Prevent Teen and Unplanned Pregnancy is How Misperceptions, Magical Thinking, and Ambivalence Put Young Adults at Risk for Unplanned Pregnancy.

The study [PDF] surveyed American singles ages 18–29 about their perceptions about and use of contraception. Twenty-eight percent of young men think that wearing two condoms at a time is more effective than just one. Twenty-five percent think that women can prevent pregnancy by douching after sex. Eighteen percent believe that they can reduce the chance of pregnancy by doing it standing up.

A staggering 42% of men and 40% of women believe that the chance of getting pregnant within a year while using the birth control pill is 50% or greater (despite research suggesting that the pill is typically 92% effective).

And many unmarried young adults believe they are infertile. Although available data suggest that about 8.4% of women 15–29 have impaired fecundity (measured as an inability to conceive or carry a baby to term): 59% of women and 47% of men say it is at least slightly likely they are infertile (19% of women and 14% of men describe it as quite or extremely likely.

In a very good short essay about the study at The Sexist, Amanda Hess links men’s lack of knowledge about contraception to their lack of knowledge about menstruation and physiology more generally, and illustrates with some telling anecdotes. There are a few more examples in the video at right, in which Amanda corners several men and asks them to explain how hormonal birth control works.

It all seems quite shocking, until one remembers that abstinence-only sex education that includes lessons about the ineffectiveness of condoms and other contraceptives has been standard in the U.S. since 1996. (See here for U.S. Government definitional criteria for abstinence-only sex education. At present, 22 states have opted out of receiving federal funding, so that they may provide accurate and comprehensive sex education.)