Deindividualization or deindividuation is a concept in social psychology which refers to a person’s loss of distinct awareness as well as lessened perception of responsibility when in a group.
For example, a student is in jail for shoplifting. He and his friends got so excited last night that they thought of committing a petty crime just for fun. Even if he didn’t initially want to do it, he got carried away by his peers’ influence and eventually did something that was very unlikely of his character. Deindividuation also pertains to the loss of individual identity when in a group. For instance, a person who does not normally appreciate slapstick humor is laughing when he is a part of the audience of a show involving clowns hitting each other.