Do Infants Expect Reciprocity Between Strangers?

Abstract

Social scientists from different disciplines have long argued that direct reciprocity plays an important role in regulating social interactions between unrelated individuals. Here we examined whether 15-month-old infants (N = 160) would expect direct positive and negative reciprocity between strangers. In violation-of-expectation experiments, infants watched successive interactions between two strangers, agent1 and agent2. After agent1 acted positively toward agent2, infants were surprised if agent2 acted negatively toward agent1 in a new context. Similarly, after agent1 acted negatively toward agent2, infants were surprised if agent2 acted positively toward agent1 in a new context. Both responses were eliminated when agent2’s actions were not knowingly directed at agent1. Additional results indicated that infants viewed it as acceptable for agent2 to either respond in kind to agent1 or not engage with her further. By 15 months of age, infants thus already expect a modicum of reciprocity between strangers: Initial positive or negative actions are expected to set broad limits on reciprocal actions. This research adds weight to long-standing claims that direct reciprocity helps regulate interactions between unrelated individuals and, as such, is likely to depend on psychological systems that have evolved to support reciprocal reasoning and behavior.