Snap judgments during speed dating

Whether or not we like to admit it, we all may make snap judgments about a new face. Perhaps nowhere is this truer than in speed dating, during which people decide on someone's romantic potential in just a few seconds. How they make those decisions, however, is not well understood.

But now, researchers at the California Institute of Technology (Caltech) have found that people make such speed-dating decisions based on a combination of two different factors that are related to activity in two distinct parts of the brain.

Unsurprisingly, the first factor in determining whether someone gets a lot of date requests is physical attractiveness. The second factor, which may be less obvious, involves people's own individual preferences -- how compatible a potential partner may be, for instance.

The study, which is published in the November 7 issue of the Journal of Neuroscience, is one of the first to look at what happens in the brain when people make rapid-judgment decisions that carry real social consequences, the researchers say.

"Psychologists have known for some time that people can often make very rapid judgments about others based on limited information, such as appearance," says John O'Doherty, professor of psychology and one of the paper's coauthors. "However, very little has been known about how this might work in real social interactions with real consequences -- such as when making decisions about whether to date someone or not. And almost nothing is known about how this type of rapid judgment is made by the brain."

In the study, 39 heterosexual male and female volunteers were placed in a functional magnetic resonance imaging (fMRI) machine and then shown pictures of potential dates of the opposite sex. They were given four seconds to rate, on a scale from 1 to 4, how much they would want to date that person. After cycling through as many as 90 faces, the participants then rated the faces again -- outside the fMRI machine -- on attractiveness and likeability on a scale from 1 to 9. Later, the volunteers participated in a real speed-dating event, in which they spent five minutes talking to some of the potential dates they had rated in the fMRI machine. The participants listed those they wanted to see again; if there were any matches, each person in the pair was given the other's contact information.

Perhaps to no one's surprise, the researchers found that the people who were rated as most attractive by consensus were the ones who got the most date requests. Seeing someone who was deemed attractive (and who also ended up with more date requests) was associated with activity in a region of the rater's brain called the paracingulate cortex, a part of the dorsomedial prefrontal cortex (DMPFC), which is an important area for cognitive control and decision making. The paracingulate cortex, in particular, has been shown to be active when the brain is comparing options.

This phenomenon was fairly consistent across all participants, says Jeff Cooper, a former postdoctoral scholar in O'Doherty's lab and first author of the paper. In other words, nearly everyone considers physical attraction when judging a potential romantic partner, and that judgment is correlated with activity in the paracingulate cortex.

"But that's not the only thing that's happening," Cooper adds. When some participants saw a person they wanted to date -- but who was not rated as very desirable by everyone else -- they showed more activation in the rostromedial prefrontal cortex (RMPFC), which is also a part of the DMPFC, but sits farther in front than the paracingulate cortex. The RMPFC has been previously associated with consideration of other people's thoughts, comparisons of oneself to others, and, in particular, perceptions of similarities with others. This suggests that in addition to physical attractiveness, the researchers say, people consider individual compatibility.

While good looks remains the most important factor in determining whether a person gets a date request, a person's likeability -- as perceived by other individuals -- is also important. For example, likeability serves as a tiebreaker if two people have equal attractiveness ratings. If someone thought a potential date was more likeable than other people did, then that someone was more likely to ask for a date.

"Our work shows for the first time that activity in two parts of the DMPFC may be very important for driving the snapshot judgments that we make all the time about other people," O'Doherty says.

As for the results of the speed-dating event? A few couples were still together six weeks afterward, Cooper says, but the researchers have not followed up. The study was focused on the neural mechanisms behind snap judgments -- how those judgments relate to long-term romantic success, he says, is another question.

This research was funded by an Irish Research Council on Science, Engineering, and Technology Fellowship, the Wellcome Trust, and the Gordon and Betty Moore Foundation.