Who’s in the in-crowd?

Being in with the in-crowd is the result of a couple of simple and well-established psychological principles that govern how we form allies and enemies, according to researchers at Yale and the University of North Carolina. We like people who are nice to us. And we like friends of our friends—and dislike our friends’ enemies. The researchers used a computer model—with just 80 lines of code—to show that these two ingredients form the recipe for “us versus them,” and published their findings in the journal Psychological Science. David Rand, Ph.D., assistant professor of psychology, economics and management, was a co-lead author of the study.