In jeans, she attracted little notice and no negative comments from the students, whose reactions were being secretly recorded during the encounter and after the woman left the room. But when she wore the other outfit, virtually all the students reacted with hostility.

They stared at her, looked her up and down, rolled their eyes and sometimes showed outright anger. One asked her in disgust, “What the [expletive] is that?”

Most of the aggression, though, happened after she left the room. Then the students laughed about her and impugned her motives. One student suggested that she dressed that way in order to have sex with a professor. Another said that her breasts “were about to pop out.”

The results of the experiment jibe with evidence that this “mean girl” form of indirect aggression is used more by adolescents and young women than by older women, who have less incentive to handicap rivals once they marry. Other studies have shown that the more attractive an adolescent girl or woman is, the more likely she is to become a target for indirect aggression from her female peers.