To test this possibility, they examined whether professional football and ice hockey teams that wear black uniforms are more aggressive than those that wear nonblack uniforms. An analysis of the penalty records of the National Football League and the National Hockey League indicates that teams with black uniforms in both sports ranked near the top of their leagues in penalties throughout the period of study. On those occasions when a team switched from nonblack to black uniforms, the switch was accompanied by an immediate increase in penalties!!!

The results of two laboratory experiments indicate that this finding can be attributed to both social perception and self-perception processes—that is, to the biased judgments of referees and to the increased aggressiveness of the players themselves. This research study focuses on the theoretical implications of these data for an understanding of the variable, or “situated,” nature of the self.

You can listen to the story on NPR here…