Toddlers prefer to help familiar people.

Young children's willingness to spontaneously help others is the subject of a large body of research investigating the ontogeny of moral behavior and thought. A developing debate centers around the extent to which social factors influence the desire to help. Familiarity with the person needing help is one such factor that varies across many studies but has not been systematically investigated. In Experiment 1, we show that toddlers were significantly more likely to assist a person on an out-of-reach clothespin task when they had previously become familiar with that person. Moreover, and in contrast to previous work, we found that becoming familiar with a person increases helpfulness only toward that person and does not transfer to an unknown person. We further demonstrate, in Experiment 2A, that children were equally likely to approach and take a sticker from an experimenter with whom they were familiar or unfamiliar-thereby ruling out wariness of strangers as the key driver for familiarity effects in Experiment 1. Moreover, in Experiment 2B, we show that children were more likely to help the previously unfamiliar partner (from Experiment 2A) after the partner gave the child the sticker. We conclude that familiarity is an ecologically important social influencer of toddler helping behavior.