Researchers Leonard Lee of Columbia University in New York, George Loewenstein of Carnegie Mellon University in Pittsburgh and Dan Ariely of the Massachusetts Institute of Technology worked with James Hong and Jim Young of HOTorNOT.com, a Web site that allows members to rate others on physical attractiveness.

The study, scheduled to be published in the journal Psychological Science, found people with similar levels of physical attractiveness tend to date each other, with more attractive people being more particular about the physical attractiveness of their potential dates.

In addition, the study found people prefer to date others who are moderately more attractive than they are. The researchers also found that most people agree on what is attractive, characteristics like symmetrical faces.

In a follow-up speed-dating study, Lee and colleagues found more attractive people placed more weight on physical attractiveness in selecting their dates, while less attractive people placed more weight on other qualities like a sense of humor.