Bystander reactions to a violent theft: crime in Jerusalem.

Seventy-two male Israeli students were exposed to a violent crime in the course of a bogus discussion. Their awareness of other bystanders' lack of reaction to the emergency (social influence) and others' awareness of their actions (evaluation apprehension) were crossed in a 2 X 2 factorial design. An "alone" condition in which the subject was the only bystander controlled for the effects of others' mere presence (diffusion of responsibility). Helping was reduced by diffusion of responsibility and slowed by negative social influence but was increased by evaluation apprehension. Differences traceable to social influence appeared prior to those from the other processes. Implications of these findings for the measurement of helping and the interpretation of bystander decision making are discussed.