Secret to friendship: Children make inferences about friendship based on secret sharing.

= 452), we examined the developmental trajectory of reasoning about secret sharing as an indication of third-party friendship. By age 6, but not before, children expected that a person would be friends with someone that she told a secret. We replicated this main finding across four studies by comparing secret sharing to other cues of affiliation. Children treated sharing a secret as a stronger cue to friendship than sharing a physical object (Study 1), sharing a fact (Studies 2-4), or sharing membership on the same sports team (Study 3). Although younger children did not understand that secret sharing indicated friendship, they did expect people to be more likely to disclose their secrets to friends than to nonfriends (Study 5). Taken together, our results indicate that children understand the social significance of sharing secrets and use secret sharing to make important predictions about the social world. Specifically, children infer social relationships based on which people know each other's secrets and expect others to share secrets selectivity with friends. (PsycINFO Database Record (c) 2018 APA, all rights reserved).