We examined how the number of groups in a categorization task influences how White Americans categorize ambiguous faces. We investigated the strength of identity-driven ingroup overexclusion-wherein highly identified perceivers overexclude ambiguous members from the ingroup-proposing that, compared with dichotomous tasks (with only the ingroup and one outgroup), tasks with more outgroups attenuate identity-driven ingroup overexclusion (a dilution effect). Fourteen studies (n = 4,001) measured White Americans' racial identification and their categorizations of ambiguous faces and manipulated the categorization task to have two groups, three groups, or an unspecified number of groups (open-ended). In all three conditions, participants overexcluded faces from the White category on average. There was limited support for the dilution effect: identity-driven ingroup overexclusion was absent in the three-group task and only weakly supported in the open-ended task. The presence of multiple outgroups may dampen the impact of racial identity on race perceptions among White Americans.
Keywords: categorization; ingroup overexclusion; racial ambiguity; racial identity.