This street-bystander scenario illustrates which phenomenon: people assume others will help and thus no one does?

• A. Diffusion of responsibility
• B. Bystander effect
• C. Social facilitation
• D. Social loafing

Answer: (A)

Diffusion of responsibility occurs when people in a group feel less personal obligation to act because others are present. In a street-bystander scenario, each person may assume that someone else will step in, so their own sense of responsibility to intervene diminishes and no one ends up helping. This mechanism explains why help is often delayed or absent even when it’s needed. This idea sits behind the broader bystander effect, which notes that the presence of more bystanders tends to reduce the likelihood of helping, but the key driver in this situation is the diffusion of responsibility. It’s not about performance changes in the presence of others or about people putting in less effort; it’s about who feels obligated to act.