What a strange illusion it is to suppose that beauty is goodness. --Leo Tolstoy

In a society that labels its most exceptional members Beautiful People, it is disturbing--but not surprising--that there is a growing tendency for us to judge each other primarily on the basis of looks.

In virtually every social situation examined, attractive people receive preferential treatment. Numerous studies indicate that good looks can lead to everything from higher grades to a lighter jail sentence--a situation lending a new twist to Freud's "anatomy is destiny."

Or, as University of Minnesota psychology Prof. Ellen Berscheid puts it: "Beauty is much more than skin deep."

"There exists a physical-attractiveness stereotype that assumes a pleasing exterior covers an equally pleasing interior," says Berscheid, who has spent 16 years researching the social and psychological implications of attractiveness.

"Attractive individuals--whether male or female, old or young, black or white, of high or low socio-economic status--are generally believed to be more sensitive, more kind, interesting, strong, poised, sociable, outgoing and exciting."

Yet what we do regarding attractiveness, conflicts with what we say.

"We feel that physical attractiveness ought not to make a difference," says Berscheid. "The knowledge or suspicion that our physical attractiveness significantly affects both the quality and the course of our lives--through how we are treated by others--appears to cause us distress, uneasiness and embarrassment."

And when attractiveness is considered important, "it's popularly thought to be limited to women," she notes. "But its impact cuts across both sexes, and all ages. A child's physical-attractiveness level may begin to affect his or her life virtually from the time they draw their first breath. The middle-aged and the elderly are not immune."

Despite our discomfort with "attractiveness stereotypes," says Berscheid, 45, reliance on them is a growing problem in our highly-mobile, divorce-ridden society. "The importance of first impressions and one-time interactions between people," she contends, "is increasing."

Acknowledgment of this "pretty prejudice" is reflected in the growing demand for cosmetic surgery. "In 1949," she notes, "only about 15,000 cosmetic surgical operations were performed in the United States, but by 1971 this figure had swollen to nearly 1 million."

Another indication is the emergence of "personal-image consultants," who teach clients how to groom themselves for success. "Although it may be comforting to cling to the notion that substance is more important than superficial externals," says the introduction to a directory of image consultants, "that notion is rapidly becoming outmoded. Appearance and speech are increasingly recognized as important factors in determining a person's success or failure in the business and social worlds."

Over the past few years, the impact of appearance has become a popular research topic. Many of the studies illustrate a "halo effect"--when one positive aspect (attractiveness) is known about a person, other positive qualities are assumed. Among the most striking results:

* In a "blind-dating" experiment, physical attractiveness alone determined how highly an individual was regarded by his or her date. Intelligence, social skills and personality had little or no effect. Yet both men and women said they deemed physical attractiveness only moderately important.

* Personnel consultants considered attractive job applicants "more qualified," even though resume's were identical.

* Nurses caring for premature infants gave a higher intellectual prognosis to those they considered physically attractive.

* Children considered attractive by adults were more popular with their nursery-school classmates. Unattractive children tended to be seen as "scary" by other children.

* Well-groomed patients received better treatment from their doctors than less dapper peers. Physicians left the room less frequently, were more courteous and employed better interviewing skills.

* Attractive females were seen as "more feminine" and more suited for traditional female roles; attractive men as "more masculine" and more suited for traditional male roles.

* Observers think more highly of an "average-looking" person if he or she is with an attractive partner.

"The evidence suggests," says Berscheid, "that the physically attractive live in a different social world than their unattractive counterparts." One result: "Appearance may affect one's mental and spiritual health."

The assumption that beautiful people are good, and ugly people are bad, may become a self-fulfilling prophesy. As an example she cites the tale of Frankenstein, in which "the monster was not originally evil. It expressed hope 'to meet with beings who, pardoning my outward form, would love me for the excellent qualities I was capable of unfolding.'

"But the creature was shunned by everyone who came into contact with it. As a result it became a monster whose inner character was congruent with his outward appearance."

Another reason for the growing importance of appearance, says Berscheid, is the "extraordinarily high standard of physical attractiveness" displayed by television and movies.

"The mass media sets a standard against which we compare other people," concurs Arizona State University psychology professor Douglas Kendrick. In his research on this "contrast effect," he found that "average-looking" people were judged as less attractive if their photo followed that of an extremely attractive person.

And after men viewed Playboy centerfolds, they rated the photo of an "average-looking" naked female as less desirable than those men who didn't see the centerfold first.

"We kind of naturally subject ourselves to this when we see TV programs like 'Charlie's Angels,' " says Kendrick. "Most of us have a very warped view of what naked bodies look like. A lot of people who go to a nude beach for the first time are surprised at how homely most of the bodies are."

Just as Aristotle declared beauty to be "a greater recommendation than any letter of introduction," attractiveness "often opens doors in business," says American University communications Prof. James Gray, author of "The Winning Image."

"In the professional world," he says, "people form their lasting impressions of you within 30 seconds of meeting you. Attractive people, regardless of sex, achieve credibility more easily and are often sought out, particularly for positions with high public visibility."

But while attractiveness may be an advantage, stunning good looks can be a liability. "Some employers might reject someone who is a knock-out," says Gray, "for fear that person would be too distracting or cause jealousies or problems. Often it depends on the type of work. Someone who fits into an artsy office may be too flashy for a bank."

Although beauty opens some doors, it shuts others, says Pennsylvania State University psychologist Lita Schwartz, who studied 46 "attractive women achievers" with Florida psychologist Florence Kaslow.

"Some said they could disarm bosses or clients with their looks," says Schwartz, "and capitalized on the advantages of being an attractive woman. But many said they felt under constant pressure to prove that beauty and brains can go together.

"Occasionally there were problems with male co-workers who mistook friendliness as an advance, or with colleague's wives who felt threatened. And several mentioned they knew some people assumed that anyone that pretty must have slept with someone to get her job."

University of Maryland psychologist Harold Sigall contends that attractive people are not always viewed more favorably, "but what an attractive person does has much more impact than what an unattractive person does."

In one experiment, a woman criticized and praised men on their performance of a task. For half the experiment she was dressed and made up to look attractive, and for the other half she appeared plain. "She was most liked when she was attractive and gave praise," says Sigall. "She was most disliked when she was attractive and gave criticism."

When she was plain, "what she did didn't matter as much to the subjects." In another experiment, Sigall found that "people will try harder to please someone who's attractive." These results suggest, he says, "that attractive people have more social power."

The "frightening aspect" of all these findings, says University of Vermont psychologist Carol T. Miller, is that "they show how we discriminate against unattractive people." In her experiments, subjects grouped people into two categories--the "attractive" and the "average" in one and the "unattractive" in another.

"The real stereotype isn't 'What is beautiful is good,' " she says, "it's 'What is ugly is bad.' Most of us are average looking, so that leaves two minority groups--attractive people who are viewed positively and ugly people who are viewed negatively."

And unlike discrimination against other minorities, "We have no constraints," she says, "against calling unattractive people names--like 'she's a dog.' Our prejudices operate at a much more subtle level."

Although researchers concur that good looks are important for first impressions, they may, in the long run, be less significant.

Image consultant and psychologist Stanley Hyman, head of Washington's Identity Research Institute, offers this encouragement to the Un-Beautiful People of the world: "Most people would rather deal with a genuine, warm human being than with a living doll.

"You can look like a mudcake, but if you do the best with what you have--and know how to relax and smile--you can come across as attractive. Look at Lee Iacocca. He looks like he's been hit by a truck, but he's a person who can make things happen. And in the business world that's what counts."

Although psychologist Berscheid admits that "the little evidence currently available suggests that the opposite may be true," further study "may support the idea that physical attractiveness doesn't count--at least with people who do count, the individual's closest friends and associates."