Why don't bystanders help? Because of ambiguity?

Two experiments investigated the effects of ambiguity of an emergency situation on helping behavior. In Experiment I, 70 male undergraduates waiting either alone, with a stranger, or with a friend heard a maintenance man fall and cry out in agony. Half of the two-person groups were naive; the other half included a confederate who was instructed to react as passively as possible. In contrast to the finding of Latane and Rodin's lady in distress...