"We're told not to judge a book by its cover, but we do this spontaneously," explained Adams. "In fact, it's quite an effort to undo the inferences that we make."

Sometimes, in fact, those inferences are dead-on. In the 1990s, psychologists Robert Rosenthal and Nalini Ambady -- who Adams later worked with at Harvard University --conducted a study in which college students were asked to evaluate a professor's teaching ability. The students' ratings were based solely on watching a muted 10-second clip of that professor in front of a class. Remarkably, these instant ratings substantially matched those given after an entire semester.

In other cases, however, such quick decisions may be misleading. This is especially true, Adams said, when the evaluation is cross-cultural. Nonverbal cues differ from culture to culture, he explained. This is less true of basic emotions such as fear and surprise, he added, and more true of complex emotions like sarcasm and humility.

In a recent experiment, Adams and his colleagues at Kyoto University in Japan were able to show evidence that test subjects were more likely to accurately "read" complex mental states such as playfulness or skepticism in members of their own race or culture group. In other words, Adams explained, Caucasian Americans recognized the facial characteristics of a particular emotion from photos of Caucasian American faces more easily than from Japanese faces. Similarly, Japanese students, who were given photographs expressing the same emotions, better identified these emotions when they were reflected in Japanese faces.

This difficulty in translating across race and culture, Adams said, may contribute to the development of stereotypes, such as that all members of an outside group look alike. One place where such barriers may have a particularly serious impact, he suggested, is within the criminal justice system, where eyewitness testimony may be greatly affected by defective memory, especially when a victim is asked to identify a criminal of a different race.

"The question is how many innocent people have been sent to jail because of a faulty first impression," said Adams. "Clearly that's when snap judgments go completely awry."

Adams and his colleagues are now faced with a new question: Is it possible to train people to do a better job of evaluating people from outside their own group? The answer, he suggested, may have important implications for military strategy, academic exchange and even transnational business.

In general, Adams said, snap judgments are most accurate in situations where an expert is making a quick decision on a familiar topic based on past experience. Therefore, it's not surprising that college students, after developing perspective on instructors' body language through numerous classes, were able to trust their intuition to rate an unfamiliar professor. "Sometimes not thinking is important," he explained. "When your body seems to know before your mind, your mind seems to get in the way."

Source: By Tia Bochnakova, Research Penn State