INTERPERSONAL RELATIONS AND GROUP PROCESSES Intergroup Aggression: Its Predictors and Distinctness From In-Group Bias Naomi Struch and Shalom H. Schwartz Hebrew University Jerusalem, Israel Investigated predictors of intergroup aggression and its relations to in-group bias. In a questionnaire, 156 Israeli adults reported perceptions of their own religious group and of the ultraorthodox Jewish out-group and expressed aggression toward the ultraorthodox (opposing institutions that serve their needs, supporting acts harmful to them, and opposing interaction with them). Respondents showed in-group favoritism in trait evaluations, but this bias was unrelated to aggression. Perceived inter- group conflict of interests, the postulated motivator of aggression, predicted it strongly. The effects of conflict on aggression were partially mediated by 2 indexes of dehumanizing the out-group (per- ceived value dissimilarity and trait inhumanity) and by 1 index of probable empathy with it (per- ceived in-group-out-group boundary permeability). These variables related to aggression more strongly among persons who identified highly with their in-group. The variables also mediated the effects of religious group affiliation on aggression. The value dissimilarity finding supports deriva- tions from belief congruence theory. One of the most reliable and widely observed phenomena in research on intergroup behavior is the occurrence of intergroup bias. This bias typically takes the form of in-group favoritism, a preference for one's in-group over the out-group, expressed in evaluation, liking, or allocation of resources (Brewer, 1979; Brewer & Kramer, 1985; Tajfel, 1982; Wilder, 1986). The evi- dence, it should be noted, is not that individuals necessarily feel negatively toward members of the out-group (Turner, 1978). In- deed, in-group favoritism is sometimes even accompanied by out-group favoritism on dimensions of lesser importance to the in-group (Mummendy & Schreiber, 1983, 1984). Is in-group favoritism related to a more socially disruptive form of intergroup bias, aggressive behavior toward the out- group? Turner (1978) suggested it might not be. The current research addresses this question directly. We also examine the role that perceptions of the out-group play in the processes lead- ing to intergroup aggression. Do perceptions of the out-group as inhumane, as dissimilar to the in-group in its basic values, and as sharply separated from the in-group mediate the impact of perceived conflict on intergroup aggression? Do these same processes also lead to in-group favoritism? This research was supported in part by grants to Shalom H. Schwartz from the Office of Science and Development of the National Council for Research and Development (Israel) and the Israel Foundations Trustees and to Naomi Struch from the Marshall Fund. We thank Israela Silberman and Einat Peleg for their aid in gathering the data and several anonymous reviewers for their helpful comments. Correspondence concerning this article should be addressed to Sha- lom H. Schwartz, Department of Psychology, Hebrew University, Mount Scopus, Jerusalem, Israel 91905. Adapting R. A. Baron's (1977) definition of aggression, we define intergroup aggression as any behavior intended to harm another person because he or she is a member of an out-group, the behavior being viewed by its target as undesirable. The con- text of this study is aggression expressed toward the ultraortho- dox Jewish subgroup in Israel by Israeli Jews. Many Israelis see this subgroup as threatening to their way of life.' Background The major theoretical approaches that have stimulated the study of intergroup behavior and the finding of in-group favorit- ism are belief congruence (Rokeach, 1960) and social identity (Tajfel, 1978, 1981,1982). Do the basic assertions of these theo- ries apply to intergroup aggression? Belief congruence theory concerns itself with the degree of similarity in beliefs, attitudes, and values perceived to exist between individuals. It asserts that dissimilarity increases negative orientations toward others. We extend this analysis to perceived similarity between the beliefs of an in-group with which one identifies and the beliefs of an out-group. Rokeach's claim (1968, 1980), that perceived dis- similarity of beliefs has more impact on racial discrimination than race itself, suggests that belief congruence theory can be applied to aggression. Social identity theory holds that individuals are motivated to 1 Israeli Jews usually classify themselves on a continuum of religious ritual observance ordered secular, traditional, orthodox, and ultraor- thodox. This order is the reverse of their proportions in the population. The ultraorthodox are perceived by the others as trying to impose their life-style on all. Journal of Personally and Social Psychology. 1989, Vol. 56. No. 3. 364-373 Copyrighl 1989 by the American Psychological Association. Inc. 0022-3514/89/$00.75 364