When it comes to assessing the romantic playing field -- who might be interested in whom -- men and women were shown to be equally good at gauging men's interest during an Indiana University study involving speed dating -- and equally bad at judging women's interest. 

Researchers expected women to have a leg up in judging romantic interest, because theoretically they have more to lose from a bad relationship, but no such edge was found. 

Place's study, published in the January issue of the journal Psychological Science, focused on the ability of observers to judge romantic interest between others because this ability has evolutionary benefits when it comes to finding a mate. Decisions that other people around us make, said Place, can influence or inform our own choices. 

"The hardest-to-read women were being misperceived at a much higher rate than the hardest-to-read men. Those women were being flirtatious, but it turned out they weren't interested at all," said lead author Skyler Place, a doctoral student in IU's Department of Psychological and Brain Sciences working with cognitive science Professor Peter Todd. "Nobody could really read what these deceptive females were doing, including other women." 

Want to try it for yourself?  Readers can see how successful they are at judging romantic interest by participating in a new online study that contains the same task as the one described here. It takes 20-minutes and you can find it  here. 

"So, if you walk into a room and there's 20 people you've never met before, being able to know which individuals might be available and which are clearly smitten by others can make you more efficient in finding your own romantic interest to pursue," he said. 

For the study, 28 women and 26 men of college age watched video clips of couples interacting on speed dates. Speed dating is a popular commercial method for singles to meet a large number of individuals in one evening of successive brief one-on-one conversations. Each participant observed 24 videos, all with different men and women, and after each rated whether the man seemed interested in the woman and the woman in the man. 

The speed dating sessions were all conducted in Germany while the observer ratings were all made by students in Indiana. Despite the language difference, observers were still able to judge men's romantic interest accurately using body language, tone of voice, eye contact, how often each dater spoke and other non-verbal cues. 

"How people talk might convey more than what they say," Place said. 

Observers did not have to see much of this non-verbal behavior. They were just as good at predicting the speed-dating couple's interest if they saw only 10 seconds of the date as they were if they saw 30 seconds. The researchers say this showed that observers, even with limited information, could make quick, accurate inferences using "thin slices" of behavior. 

There was, however, great variability in how well observers could predict the interest of any particular speed-dater, ranging from 90 percent accuracy down to 10 percent. In five of the videos, 80 percent of the observers thought the women shown were interested when in fact they were not -- they were acting friendly even though they had no interest in the men. 

Evolutionary theory, said Place, predicts a certain level of coyness or even deceptiveness in women because if a relationship is abandoned they may face greater costs, including pregnancy and child rearing. When choosing a mate, it is in a woman's best interest to get men to open up and talk honestly to give her a better idea of whether they would be good long-term partners. 

"In a speed dating environment, you would expect to see these effects dramatically, with the women trying to get the men to be more straightforward, while they themselves remain more coy," Place said. "Though the pace is faster than a typical first date, the strategy remains the same." 

Co-authors include Peter M. Todd, Cognitive Science Program, in the College of Arts and Sciences at IU Bloomington; Lars Penke, University of Edinburgh in Scotland; and Jens B. Asendorpf, Humboldt University of Berlin. 

Article: Place, S. S., Todd, P. M., Penke, L.,&Asendorpf, J. B. (2009). "The ability to judge the romantic interest of others." Psychological Science, 20(1), 22-26.