Two studies examined the effects of group inclusiveness and the strength of group identification on intergroup attributional bias. Thirty-seven Hakka students (Study 1) and 53 Chaoshanese students (Study 2) in China read scenarios in which members of an excessively inclusive in-group, optimally inclusive in-group, or an out-group engaged in desirable or undesirable behaviors. They then made causal attributions for each behavior. Results consistently showed that intergroup attributional bias (i.e., attributing desirable behaviors of in-group members to internal causes and undesirable behaviors to external causes; for events associated with members of out-groups, opposite directions of attributions are observed) was especially visible when the in-group size was optimally inclusive. Moreover, in-group identification with optimally inclusive in-group was stronger than that with excessively inclusive in-group. The strength of group-identification was positively correlated with the magnitude of intergroup attributional bias at the individual level. The results were interpreted from the viewpoint of Self-Categorization Theory.

Key words: causal attribution, attribution bias, group identification, self-categorization