the diminished sense of responsibility often experienced by individuals in groups and social collectives. The diffusion has been proposed as a possible mediator of a number of group-level phenomena, including the bystander effect, choice shifts, deindividuation, social loafing, and reactions to social dilemmas. See also confusion of responsibility. [first described in 1970 by U.S. social psychologists John M. Darley (1938– ) and Bibb Latané (1937– )]