Oxytocin reduces the willingness to sacrifice in-group targets to save a larger collective but not the readiness to sacrifice out-group targets. Results range from 0 to 5 (displayed ± SE). (A) Results for experiment 4 with Arabs as out-group. (B) Results for experiment 5 with Germans as out-group. From De Dreu, CK. Greer LL. Van Kleff GA. et al. Oxytocin promotes human ethnocentrism.   PNAS   2011:108 (4); 1264.
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