Group behavior during conflict often affects the actions of an individual. The bystander effect introduced by Darley and Latane (1968) demonstrates that group behavior causes individuals to monitor whether others think it is necessary to react in a situation and thus base their behavior on this judgment. They also found that individuals are more likely to diffuse responsibility in group situations. These theories can be applied to situations of conflict and genocide in which individuals remove personal responsibility and therefore justify their behavior. Social identity theory explains that during the Holocaust of World War II political leaders used the Jews as an out-group in order to increase in-group cohesion. This allowed for the perpetrators to depersonalize from the situation and to diffuse their responsibility. The out-groups were held in separate confines and dehumanized in order to aid the in-group to disengage themselves from relating.