The Out-Group Homogeneity Effect Across Development: A Cross-Cultural Investigation.

The present studies investigated the out-group homogeneity effect in 5- and 8-year-old Israeli and German children (n = 150) and adults (n = 96). Participants were asked to infer whether a given property (either biological or psychological) was true of an entire group-either the participants' in-group ("Jews" or "Germans") or their out-group ("Arabs" or "Turks"). To that end, participants had to select either a homogenous or a heterogeneous sample of group members. It was found that across ages and countries, participants selected heterogeneous samples less often when inferring the biological properties of out-compared to in-group members. No effect was found regarding psychological properties. These findings have important implications for our understanding of the origins of intergroup bias.