Development of the positive-negative asymmetry effect: In-group exclusion norm as a mediator of children’s evaluations on negative attributes.

Two studies were conducted that go beyond previous research by examining when and why children might show intergroup bias in the attribution of positive, but not negative traits (PNAE: the positive-negative asymmetry effect, Mummendey & Otten, 1998). In Study 1 (n = 107) children completed a ‘mixed’ trait attribution task in a dichotomous group context. As predicted there was a developmental trend between 7 and 12 years of age in the PNAE. The seven year olds were the only age group not to show the effect. Study 1 also found a quadratic developmental trend in children’s national intergroup bias. Study 2 (n = 62) replicated the developmental path of the PNAE found in Study 1 using a wider age range of 6 to 16 years. This study used a ‘mixed’ list of traits which weren’t only antonyms and a procedure that made the positive and negative trait dimensions explicitly independent. Significantly, Study 2 found ingroup exclusion norm partially mediated the development of the PNAE. These findings support an account of the positive-negative asymmetry effect based upon normative processes.