The tendency for awareness of one's individual identity to decline when they are in a group setting is called

The correct answer is deindividuation

Deindividuation refers to the phenomenon in social psychology, in which individual's lose their sense of individual and personal identity when they are part of a group. In a deindividuated state, individuals additionally feel less responsible for their actions. Deindividuation can be an explanation for unified mob mentality, crowd behavior and riots.