Psychology professor Dr. Norman Brown said while some people might conclude this happens because "men are pigs," there is in fact, important information to be gathered from his survey of approximately 1,100 Albertans, who were asked to recall how many sexual partners they had had during their lives.
"Some would say men overestimate the number of partners they have had because they are pigs and like to boast and brag about their conquests," Brown said.
"From my research over the last 20 years, I know there is much more to it than this," he said. Brown works in the area of cognitive psychology and is interested in how people acquire, organize, and utilize real-world knowledge (i.e., facts about the world learned through experience).
In 1999, together with research partner Dr. Robert Sinclair, Brown surveyed University of Alberta students on the same question about numbers of sexual partners and came up with similar results. In this more recent survey, conducted with the help of the U of A Population Research Laboratory, a cross section of heterosexual men and women throughout Alberta were asked how many sexual partners they've had in their lives. After they answered this question, they were asked how they came up the number they gave.
When asked the question, 'how many partners have you had in your lifetime?', two-thirds of women said they knew precisely and reported an average of 6.2. Men on the other hand were twice as likely to say they had no idea and on average guessed 11.9.
Brown said this result was most interesting.
"Every time a man has sex with a woman, a woman has to have sex with a man. So either there are some very lucky joes out there or someone is not getting their numbers right," Brown said.
By asking respondents how they came up with their number, Brown was able to work out what methods men and women were more likely to use when calculating the number of sexual partners.
He found that men were twice as likely as women to use a rough approximation method, while women were more likely to think about individual incidents and calculate the number this way. People who had had few sexual partners were the most likely to use the reasoning "I just know."
It remains, however, unclear as to how male overestimation could result in such a wide disparity in the reported number of lifetime sexual partners. Brown has three theories, none of which are very flattering to men. One is that men cannot be bothered to remember individual lovers. The next is that men are lazy and have not got the patience to think seriously when answering a telephone poll, and the third one is his 'Don Juan' theory that there might in fact be a number of men in Alberta who have been, in Brown's words, "lucky joes."
Brown said his findings have applicability in a number of areas, including strategies for dealing with people who engage in high-risk sexual behaviour.