From empathy and sexuality to science inclination and extroversion, statistical analysis of 122 different characteristics involving 13,301 individuals shows that men and women, by and large, do not fall into different groups. In other words, no matter how strange and inscrutable your partner may seem, their gender is probably only a small part of the problem.
"People think about the sexes as distinct categories," says Harry Reis, professor of psychology at the University of Rochester and a co-author on the study to be published in the February issue of the Journal of Personality and Social Psychology. "´Boy or girl?´ is the first question parents are asked about their newborn, and sex persists through life as the most pervasive characteristic used to distinguish categories among humans."
The authors reached that conclusion by reanalyzing data from 13 studies that had shown significant, and often large, sex differences. Reis and Carothers also collected their own data on a range of psychological indicators. They revisited surveys on relationship interdependence, intimacy, and sexuality. They reopened studies of the "big five" personality traits: extroversion, openness, agreeableness, emotional stability, and conscientiousness. They even crunched the numbers on such highly charged and seemingly defining gender characteristics as femininity and masculinity. Using three separate statistical procedures, the authors searched for evidence of attributes that could reliably categorize a person as male or female.
Statistically, men and women definitely fall into distinct groups, or taxons, based on anthropometric measurements such as height, shoulder breadth, arm circumference, and waist-to-hip ratio. And gender can be a reliable predictor for interest in very stereotypic activities, such as scrapbooking and cosmetics (women) and boxing and watching pornography (men).
But for the vast majority of psychological traits, including the fear of success, mate selection criteria, and empathy, men and women are definitely from the same planet. Instead of scores clustering at either end of the spectrum—the way they do with, say, height or physical strength—psychological indicators fall along a linear gradation for both genders. With very few exceptions, variability within each sex and overlap between the sexes is so extensive that the authors conclude it would be inaccurate to use personality types, attitudes, and psychological indicators as a vehicle for sorting men and women.
Average differences do exist, write the authors. "The traditional and easiest way to think of gender differences is in terms of a mean difference," Carothers and Reis write. But such differences "are not consistent or big enough to accurately diagnose group membership" and should not be misconstrued as evidence for consistent and inflexible gender categories, they conclude.
The best evidence we have that the so-called Mars/Venus gender division is not the true source of friction within relationships, says Reis, is that "gay and lesbian couples have much the same problems relating to each other that heterosexual couples do. Clearly, it´s not so much sex, but human character that causes difficulties."
The findings support the "gender similarities hypothesis" put forth by University of Wisconsin psychologist Janet Hyde. Using different methods, Hyde has challenged "overinflated claims of gender differences" with meta-analyses of psychology studies, demonstrating that males and females are similar on most, though not all, psychological variables.
The authors acknowledge that the study is based largely on questionnaires and may not fully capture real life actions. "Methods that more pointedly measure interpersonal behaviors (how many birthday cards have they sent this year, how many times a month do they call a friend just to see how he or she is, etc.) may more readily reveal a gender taxon," they write.
By the same token, however, as gender roles are liberalized, the authors speculate that new studies may show even less divergence between men and women in the United States. The opposite may be the case in cultures that are far more prescriptive of male and female roles, such as Saudi Arabia, Reis and Carothers predict.