Behavioral Contagion

Behavioral contagion is the spread of a behavior through a group as people copy the actions of others around them or others they have been exposed to. Gustave Le Bon coined the term in his 1895 book The Crowd: A Study of the Popular Mind to describe how undesirable behavior could spread through a crowd. Later researchers developed theoretical accounts of the mechanism: Fritz Redl proposed in 1949 that behavioral contagion works through a reduction of restraints, an account Ladd Wheeler analyzed further in 1966, and a 1979 definition by Ogunlade described it as spontaneous, unsolicited and uncritical imitation, more likely when the observer and the model are in a similar situation, when the model's behavior signals that acting the same way is acceptable, when imitating reduces conflict, and when the model is viewed positively. The concept is related to research on deindividuation by Festinger, Pepitone and Newcomb in 1952 and to later work by Freedman and colleagues in 1980 examining how factors such as group size and density affect the spread of behavior, and it has since been extended to describe the spread of behavior and information online.