▪ Abstract This chapter reviews the extensive literature on bias in favor of in-groups at the expense of out-groups. We focus on five issues and identify areas for future research: (a) measurement and conceptual issues (especially in-group favoritism vs. out-group derogation, and explicit vs. implicit measures of bias); (b) modern theories of bias highlighting motivational explanations (social identity, optimal distinctiveness, uncertainty reduction, social dominance, terror management); (c) key moderators of bias, especially those that exacerbate bias (identification, group size, status and power, threat, positive-negative asymmetry, personality and individual differences); (d) reduction of bias (individual vs. intergroup approaches, especially models of social categorization); and (e) the link between intergroup bias and more corrosive forms of social hostility.

Contact researchers have largely overlooked the potential for negative intergroup contact to increase prejudice. In Study 1, we tested the interaction between contact quantity and valence on prejudice toward Black Australians ( n = 1,476), Muslim Australians ( n = 173), and asylum seekers ( n = 293). In all cases, the association between contact quantity and prejudice was moderated by its valence, with negative contact emerging as a stronger and more consistent predictor than positive contact. In Study 2, White Americans ( n = 441) indicated how much positive and negative contact they had with Black Americans on separate measures. Although both quantity of positive and negative contact predicted racism and avoidance, negative contact was the stronger predictor. Furthermore, negative (but not positive) contact independently predicted suspicion about Barack Obama’s birthplace. These results extend the contact hypothesis by issuing an important caveat: Negative contact may be more strongly associated with increased racism and discrimination than positive contact is with its reduction.

Distinctions are made between global and specific, personal and social, and trait and state self-esteem, and these are used to structure a review of over 40 studies concerning social identity theory's hypothesis that (a) intergroup discrimination elevates self-esteem and (b) low self-esteem motivates discrimination. It is observed that researchers have tended to employ measures of global personal trait self-esteem in their investigations of this self-esteem hypothesis, and it is argued that measures of specific social state self-esteem are more consistent with social identity theory's assumptions. Although no convincing evidence is found for the self-esteem hypothesis in its full and unqualified form, it is argued that this is due to a lack of specificity in its formulation and it is suggested that a more qualified and specific version of the hypothesis may be more appropriate.

Drawing from the intergroup contact model and self-categorization theory, the authors advanced the novel hypothesis of a valence-salience effect, whereby negative contact causes higher category salience than positive contact. As predicted, in a laboratory experiment of interethnic contact, White Australians (N = 49) made more frequent and earlier reference to ethnicity when describing their ethnic contact partner if she had displayed negative (vs. positive, neutral) nonverbal behavior. In a two-wave experimental study of retrieved intergenerational contact, American young adults (N = 240) reported age to be more salient during negative (vs. positive) contact and negative contact predicted increased episodic and chronic category salience over time. Some evidence for the reverse salience-valence effect was also found. Because category salience facilitates contact generalization, these results suggest that intergroup contact is potentially biased toward worsening intergroup relations; further implications for theory and policy making are discussed.