Socially excluded people may act aggresively toward others

People who feel socially rejected are more likely to see others' actions as hostile and are more likely to behave in hurtful ways toward people they have never even met, according to a new study.

The findings may help explain why social exclusion is often linked to aggression – which sometimes boils over dramatically, as in the case of school shootings, for example.

"Prior case studies show the majority of school shooters have experienced chronic peer rejection," said the study's lead author, C. Nathan DeWall, Ph.D., from the University of Kentucky. "And while not everyone who feels rejected reacts violently, we found they tend to act out aggressively in other ways. We wanted to help explain psychologically why this happens." A full report of the study appears in the January issue of the Journal of Personality and Social Psychology, published by the American Psychological Association.

DeWall conducted four separate experiments with 190 participants, all college students.

In one experiment, 30 participants completed a personality test and were given bogus feedback about the results. A third of the participants, the excluded group, were told their personalities would mean they would probably end up alone later in life. The rest of the participants, the control group, were either told they would have many lasting and meaningful relationships or were given no feedback at all.