The phenomenon and its discovery
According to social identity theory, people tend to rate the ingroup more favorably than outgroups. Yet Marques and colleagues (1988) asked Belgian students to rate likable and unlikable behavior by students from their own and another university and found that an unlikable ingroup member was rated worse than an outgroup member who behaved the same way. A likable ingroup member, meanwhile, was rated highest. The effect was stronger among people who identified strongly with the group. They called it the black sheep effect, after the animal that stands out from the flock.
Explanation: subjective group dynamics
Marques and Paez (1994) explained that a deviant ingroup member threatens the group's positive image, so people derogate and effectively push the deviant out to protect that image. Marques and colleagues (1998) developed this into subjective group dynamics, arguing that people manage not only comparisons between groups but also conformity to norms within the group. Abrams and colleagues (2000) showed that anti-norm deviants are rejected while pro-norm deviants, who follow norms even more strongly, are judged leniently. Eidelman and Biernat (2003) suggested that derogation may also serve individual self-protection, distancing oneself from the deviant.
Development and conditions
Abrams and colleagues (2003) found that children begin to dislike ingroup peers who break norms from around age seven, with such judgments becoming more refined with age. Pinto and colleagues (2010) showed that the effect is strong for deviant full members but weak for newcomers not yet fully included and for members about to leave. The effect helps explain strong hostility toward traitors and misfits in organizations, sports fandoms and political parties, as well as social exclusion. Research continues on when and how it coexists with ingroup favoritism.
FAQ
- What is the black sheep effect in simple terms?
- When someone on your own side does something wrong, you tend to criticize them more harshly than someone from the other side who did the same thing.
- Why are people harsher on their own side?
- A misbehaving ingroup member can spoil the whole group's good image, so people derogate that member to protect the group's image.
Sources reviewed: 2026-10-26
References
- Marques, J. M., Yzerbyt, V. Y., & Leyens, J.-P. (1988). The "black sheep effect": Extremity of judgments towards ingroup members as a function of group identification. European Journal of Social Psychology, 18(1), 1–16. The founding report of the black sheep effect.
- Marques, J. M., & Paez, D. (1994). The 'black sheep effect': Social categorization, rejection of ingroup deviates, and perception of group variability. European Review of Social Psychology, 5(1), 37–68. A review grounding the effect in social identity processes.
- Marques, J. M., Abrams, D., Paez, D., & Martinez-Taboada, C. (1998). The role of categorization and in-group norms in judgments of groups and their members. Journal of Personality and Social Psychology, 75(4), 976–988. Links the effect to protection of ingroup norms.
- Abrams, D., Marques, J. M., Bown, N., & Henson, M. (2000). Pro-norm and anti-norm deviance within and between groups. Journal of Personality and Social Psychology, 78(5), 906–912. Compares pro-norm and anti-norm deviance.
- Eidelman, S., & Biernat, M. (2003). Derogating black sheep: Individual or group protection? Journal of Experimental Social Psychology, 39(6), 602–609. Tests whether derogation protects the individual or the group.
- Abrams, D., Rutland, A., & Cameron, L. (2003). The development of subjective group dynamics: Children's judgments of normative and deviant in-group and out-group individuals. Child Development, 74(6), 1840–1856. Traces the development of the effect in children.
- Pinto, I. R., Marques, J. M., Levine, J. M., & Abrams, D. (2010). Membership status and subjective group dynamics: Who triggers the black sheep effect? Journal of Personality and Social Psychology, 99(1), 107–119. Membership status moderates the black sheep effect.