Bystander anonymity and reactions to emergencies.

The impact of anonymity on bystander reactions to emergencies and on the timing of bystander decision-making was investigated in two laboratory experiments. The experiments differed in the nature of the emergency developed from relative ambiguity to unequivocal clarity concerning the victim's need for help. In both experiments, an additional bystander's awareness of the emergency and the subject's anonymity were crossed in a 2 X 2 factorial design. Anonymity vis-à-vis the victim had no effects on helping. Anonymity vis-à-vis the other bystander did affect helping, apparently by reducing evaluation apprehension. Whether evaluation apprehension enhances or inhibits helping depends on the expectations attributed to other bystanders. Anonymity may also inhibit helping by reducing involvement. The timing of effects suggests that when emergencies are ambiguous, anonymity (through reduced involvement) delays making the decision regarding whether help is appropriate. Once emergencies are clear, anonymity (through evaluation apprehension) influences the decision regarding one's own obligation to intervene.