[1][2] The term was coined by Jacques-Philippe Leyens and colleagues in the early 2000s to distinguish what they argue to be an everyday phenomenon from dehumanisation (denial of humanness) associated with extreme intergroup violence such as genocide.
Researchers have typically investigated infrahumanisation by looking at the types of emotions people believe ingroup and outgroup members possess.
In a series of studies, Leyens and colleagues have widely replicated the finding that people attribute uniquely human emotions to the ingroup, but not the outgroup.
In a series of studies, Jeroen Vaes and his colleagues investigated people's reactions to outgroup members who attempt to "humanise" themselves through the use of uniquely human emotions.
[4][clarification needed] In an American context, Cuddy and colleagues[5] have investigated the influence of infrahumanisation on intergroup helping behaviour.