Another study at Western Illinois University of paired college students who agreed to complete five dates revealed, contrary to expectation, that as the number of dates increased, attractiveness became a more important factor in determining if the partner was liked.

Young adults asked to describe the personalities of people depicted in head-and-shoulder photographs said that those who were physically attractive would be ''more sensitive, kind, interesting, strong, poised, modest, sociable, outgoing, exciting and sexually warm and responsive persons,'' according to Dr. Dion, who is now at the University of Toronto. The attractive people were also thought to ''capture better jobs, have more successful marriages and experience happier and more fulfilling lives'' than the less attractive. On only one measure, being a better parent, were the attractive not rated as superior.

In a study at the University of Minnesota, men and women whose telephone conversations were recorded were informed that they were talking either to a physically attractive person or to someone who was not attractive. The taped conversations were later evaluated by judges who were unaware of the setup.

''A woman who was talking to a man who believed that she was physically attractive was judged, on the basis of her verbal behavior alone, to be more poised, more sociable, more vivacious, than was a woman who was talking to a man who believed her to be physically unattractive,'' Dr. Berscheid reported. And the men who thought they were talking to a physically attractive woman were judged by outside observers, again on the basis of their conversations only, to be more sociable, sexually warm, interesting, independent, bold, outgoing, humorous and socially adept.

As women become more independent socially and economically, Dr. Berscheid sees them placing a greater emphasis on the attractiveness of men, ''who are now in the 'meat market' just like women have always been.'' She cited the recent advent of male centerfolds and male nude dancers as examples of women's interests in how men look.

Another factor has been the importance women today place on love as a criterion for choosing a mate. In 1967 only 24 percent of women questioned said they would marry only if they were in love, but a decade later 80 percent said ''being in love'' was a necessary condition for marriage.

''When romantic love becomes an important factor in social choice, physical attractiveness becomes important also,'' Dr. Berscheid told a symposium on the psychological aspects of facial form last year. The symposium brought together plastic surgeons, dentists and others who produce facial changes that often affect patients more powerfully than the functional defects they correct.