Science + Technology

Sexual Orientation Revealed by Body Type and Motion, Study Suggests


An individual's body motion and body type can offer subtlecues about their sexual orientation, but casual observers seem better able toread those cues in gay men than in lesbians, according to a new study in theSeptember issue of the Journal of Personality and SocialPsychology.

"We already know that men and women are built differentlyand walk differently from each other and that casual observers use thisinformation as clues in making a range of social judgments," said lead authorKerri Johnson, UCLA assistant professor of communication studies. "Now we'vefound that casual observers can use gait and body shape to judge whether astranger is gay or straight with a small but perceptible amount of accuracy."

Johnson and colleagues at New York Universityand Texas A&M measured the hips, waists andshoulders of eight male and eight female volunteers, half of whom were gay andhalf straight. The volunteers then walked on a treadmill for two minutes as athree-dimensional motion-capture system similar to those used by the movieindustry to create animated figures from living models made measurements of thetheir motions, allowing researchers to track the precise amount of shoulderswagger and hip sway in their gaits.

Based on these measurements, the researchers determined thatthe gay subjects tended to have more gender-incongruent body types than theirstraight counterparts (hourglass figures for men, tubular bodies for women) andbody motions (hip-swaying for men, shoulder-swaggering for women) than theirstraight counterparts.

In addition, 112 undergraduate observers were shown videosof the backsides of the volunteers as they walked at various speeds on thetreadmill. The observers were able to determine the volunteers' sexualorientation with an overall rate of accuracy that exceeded chance, even thoughthey could not see the volunteers' faces or the details of their clothing.Interestingly, the casual observers were much more accurate in judging theorientation of males than females; they correctly categorized the sexualorientation of men with more than 60 percent accuracy, but their categorizationof women did not exceeded chance.

The findings build on recent research that shows that casualobservers can often correctly identify sexual orientation with very limitedinformation. A 1999 Harvard study, for example, found that just by looking atthe photographs of seated strangers, college undergraduates were able to judgesexual orientation accurately 55 percent of the time.

"Studies like ours are raising questions about the value ofthe military's 'don't ask, don't tell' policy," Johnson said. "If casualobservers can determine sexual orientation with minimal information, then thevalue in concealing this information certainly appears questionable. Given thatwe all appear to be able to deduce this information to some degree with just aglance, more comprehensive policies may be required to protect gays againstdiscrimination based on their sexual orientation."

The findings also are part of mounting evidence suggestingthat sexual orientation may actually be what social scientists call a "masterstatus category," or a defining characteristic thatobservers cannot help but notice and which has been scientifically shown tocolor all subsequent social dealings with others.

"Once you know a person's sexual orientation, the fact hasconsequences for all subsequent interactions, and our findings suggest thatthis category of information can be deduced from subtle clues in bodymovement," Johnson said.



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