The Bystander Effect

Confederates are people in research experiments who seem to be regular participants, but are actually part of the experiment. And being with a confederate changes their behaviour from what they would do when they're alone. For every extra individual that is present, the amount of helping goes up by a factor of one point one. The mon explanation for the bystander effect is there's a lot of hand ringing about the dissolution of society and something called diffusion of responsibility.