Something happens to individuals when they are in a group. They think and act differently than they would on their own. Most people, if they observe some disaster or danger on their own—a woman being stabbed, a pedestrian slammed by a hit-and-run driver—will at least call for help; many will even risk their own safety to intervene. But if they are in a group observing the same danger, they hold back. The reason has more to do with the nature of groups than the nature of individuals.
In one experiment in behavioral psychology, students were seated in a room, either alone or in groups of three, as a staged emergency occurred: Smoke began pouring through the vents. Students who were on their own usually hesitated a minute, got up, checked the vents and then went out to report what certainly seemed like a fire. But the students who were sitting in groups of three did not move. They sat there for six minutes, with smoke so thick they could barely see, rubbing their eyes and coughing.
In another experiment, psychologists staged a situation in which people overheard a loud crash, a scream and a woman in pain, moaning that her ankle was broken. Seventy percent of those who were alone when the “accident” occurred went to her aid, compared with only 40 percent of those who heard her in the presence of another person.
Psychologists call this “diffusion of responsibility” or “social loafing.” The more people in a group, the lazier each individual in it becomes. Often, observers think nothing needs to be done because someone else has already taken care of it, and the more observers there are, the less likely any one person is to call for help.