Introduction People derive their sense of dignity or self-esteem not just from their own personal characteristics and achievements but also from their membership of a particular group. Such groups can be defined by nationality, ethnicity or gender or on the basis of a particular profession, club affiliation or school. The relationships between groups are not like those between individuals. One important difference is that intergroup competitiveness, rivalry or even hostility can be far more intense and extreme than its interpersonal equivalent. Researchers have dubbed this the ‘discontinuity effect’ (Insko et al., 1998; Wildschut & Insko, 2007).