I’m sure many of you will have, at some point in your lives, been admonished “not to judge a book by its cover.”This old idiom advises us that we shouldn’t judge or treat others differently based on their appearance alone. Coupled with that other saying—“beauty is but skin deep”—age-old wisdom would seem to suggest that a person’s physical appearance is rather trivial and doesn’t reflect their real, inner qualities.What about you? Have you ever judged a book by its cover?Let me put the question to you a little differently: Do you think you make different judgments about attractive and less attractive people? Chances are, you probably do, even if you wouldn’t want to admit it! Decades of psychological research have shown that a person’s physical appearance can have a huge impact on how they’re perceived and treated by others.QUIZ: How Satisfied Are You With Your Face?“What is Beautiful is Good”Consider this classic study by Elaine Walster and her colleagues. College students were invited to a dance and, when they arrived to pick up their tickets, the researchers secretly rated each participant’s attractiveness. The students then completed a survey about their personality, intelligence, and personal information, and were later randomly paired up with another participant, who would be their date for the dance. Halfway through the dance, the students completed another survey about their dates and how interested they were in a second date.So, what do you think affected the romantic attraction these participants felt toward their date? Their date’s intelligence or personality? Or the degree to which the pairs shared common interests? It turns out, the only predictor of romantic interest was how attractive the date was, regardless of participants’ own attractiveness. Participants who’d been paired up with attractive dates were more likely to show an interest in their partner, want to go on a second date, and even more likely to actually ask their date out.This classic study shows just how important physical attractiveness can be in our everyday lives. In fact, many studies have shown that we make judgments about others based solely on their appearance.We judge books by their covers.In another classic study, Ellen Berscheid and her colleagues asked participants to view photos of a physically attractive person and a physically unattractive person. The participants then rated the people they saw in the photos along a number of different dimensions.What the researchers found was that participants made all kinds of positive attributions of the attractive person, based solely on the photographs they saw. For example, they judged the attractive person as being more interesting and having more a desirable personality. They even judged the attractive person as being more likely to get a prestigious job, to have a happier marriage, and to lead a happier life in general.This study is often said to demonstrate a ‘what is beautiful is good’ bias. In our perceptions of other people, we tend to think that attractive people are ‘good’ along all kinds of dimensions. In fact, other studies have suggested that we judge attractive people as being more honest, less maladjusted, more sociable and popular, and generally better at everything they do!So much for beauty being skin deep. Whether we do it consciously or not, the evidence suggests that we assume a person’s physical attractiveness reflects their inner qualities.MORE: Is Your Mate Hotter Than You?Ugly StereotypesThis bias is even reflected in popular media. In mainstream films, for example, physically attractive characters are much more likely to play the lead and play ‘good’ rather than ‘bad’ characters. Consider, for example, the difference between the two versions of Monica in the hit sitcom “Friends.” In her younger and less attractive version, Monica was depicted as being lazy, greedy, lacking self-control and unpopular. In her older and more attractive version, she’s none of those things.The million-dollar question, of course, is how accurate these stereotypes are. In might turn out to be that attractive people really are more popular or happier, in which case it might make sense to judge a book by its cover. It turns out there might be a kernel of truth in this assumption. Recent work by Judith Langlois and her colleagues has suggested that, compared to less attractive individuals, attractive adults are in fact more popular and experienced daters.It’s quite possible that differential judgment and treatment of attractive individuals lead them to internalize those judgments. In time, they might come to develop behaviors and self-perceptions that are consistent with those stereotypes. For example, if I’m constantly treated as though I were popular, in time I might come to believe that I really am more popular than most people and alter my behaviors to suit (say, by being more affable in my social interactions).RESEARCH: Friends Hotter Than StrangersDo You Judge?It’s important to note, however, that while attractive people may really be more popular and experienced daters, there isn’t much evidence to suggest actual difference along other dimensions. For example, some scholars have suggested that differences between attractive and less attractive people tend to be trivial, with very few (if any) differences in the real world. In other words, stereotypes we have about attractive individuals are really just that—stereotypes.The other question you might ask is, “So what?” So what that we judge people differently based on their appearance? In a sense, I suppose, it doesn’t really matter whether we judge a book by its cover or not. The real problem is what happens when we treat people differently based on their appearance.As I’ll show you in my next column, there’s a lot of evidence to suggest that being attractive has its premiums. Until next time, though, have a think about how often you judge others based on their appearance.