 It is considered to be more effective to have members of each group playing complementary roles in the achievement of the goal, although the evidence to support this idea is mixed.Some also argue that with an absence of trust, the prospect of working together to achieve a mutual goal may not serve to bring groups to a superordinate identity.In some cases, when there are inequalities of power or a lack of trust among groups, the idea that they must work together and foster trust and positive interdependence may backfire and lead to more discrimination rather than less.