The bystander effect describes the reduced likelihood of an individual offering aid during an emergency when others are present. This phenomenon stems from the assumption that another person will step in or a diffusion of responsibility within a group. Consequently, an increase in the number of bystanders correlates with a decrease in the probability of any single individual providing assistance.
- Option (B), "People conform to group norms under social pressure," describes social conformity, which is distinct from the bystander effect.
- Option (C), "Individuals mimic the behavior of others in ambiguous situations," refers to social imitation or social proof, not the bystander effect.
- Option (D), "Social loafing increases in larger groups," denotes the reduction of individual effort in a group setting, a phenomenon separate from the bystander effect.
Therefore, the correct answer is (A), which posits that individuals are more inclined to assist when alone compared to when in the presence of others.