The study explored how the meaning of prosocial behavior changes over toddlerhood. Sixty-five 18-and 30-month-olds could help an adult in 3 contexts: instrumental (action based), empathic (emotion based), and altruistic (costly). Children at both ages helped readily in instrumental tasks. For 18-month-olds, empathic helping was significantly more difficult than instrumental helping and required greater communication from the adult about her needs. Altruistic helping, which involved giving up an object of the child's own, was the most difficult for children at both ages. Findings suggest that over the 2nd year of life, prosocial behavior develops from relying on action understanding and explicit communications to understanding others' emotions from subtle cues. Developmental trajectories of social-cognitive and motivational components of early helping are discussed.

The ontogeny of human empathy is better understood with reference to the evolutionary history of the social brain. Empathy has deep evolutionary, biochemical, and neurological underpinnings. Even the most advanced forms of empathy in humans are built on more basic forms and remain connected to core mechanisms associated with affective communication, social attachment, and parental care. In this paper, we argue that it is essential to consider empathy within a neurodevelopmental framework that recognizes both the continuities and changes in socioemotional understanding from infancy to adulthood. We bring together neuroevolutionary and developmental perspectives on the information processing and neural mechanisms underlying empathy and caring, and show that they are grounded in multiple interacting systems and processes. Moreover, empathy in humans is assisted by other abstract and domain-general high-level cognitive abilities such as executive functions, mentalizing and language, as well as the ability to differentiate another's mental states from one's own, which expand the range of behaviors that can be driven by empathy.

The developmental origins of sharing remain little understood. Using procedures adapted from research on prosocial behavior in chimpanzees, we presented 18- and 25-month-old children with a sharing task in which they could choose to deliver food to themselves only, or to both themselves and another person, thereby making it possible for them to share without personal sacrifice. The potential recipient, a friendly adult, was either silent about her needs and wants or made them explicit. Both younger and older toddlers chose randomly when the recipient was silent. However, when the recipient vocalized her desires 25-month-olds shared whereas younger children did not. Thus, we demonstrate that children voluntarily share valued resources with others by the end of the second year of life, but that this depends on explicit communicative cues about another’s need or desire.

What role does socialization play in the origins of prosocial behavior? We examined one potential socialization mechanism, parents’ discourse about others’ emotions with very young children in whom prosocial behavior is still nascent. Two studies are reported, one of sharing in 18- and 24-month-olds (n = 29), and one of instrumental and empathy-based helping in 18- and 30-month-olds (n = 62). In both studies, parents read age-appropriate picture books to their children and the content and structure of their emotion-related and internal state discourse were coded. Results showed that children who helped and shared more quickly and more often, especially in tasks that required more complex emotion understanding, had parents who more often asked them to label and explain the emotions depicted in the books. Moreover, it was parents’ elicitation of children’s talk about emotions rather than parents’ own production of emotion labels and explanations that explained children’s prosocial behavior, even after controlling for age. Thus, it is the quality, not the quantity, of parents’ talk about emotions with their toddlers that matters for early prosocial behavior.

a b s t r a c tRecent research on distributive justice suggests that young children prefer equal distributions. But sometimes unequal distributions are justified, such as when some individuals deserve more than others based on merit, need, or agreed-upon rules. When and how do children start incorporating such factors in their distributive decisions? Three-, 5-, and 8-year-old children (N = 72) had the opportunity to allocate several items to two individuals. One individual was neutral and the other provided a reason why she should be favored. Three of these reasons were legitimate (based on merit, need, or agreed-upon rules) whereas a fourth was idiosyncratic ("I just want more."). We found that with age, children's equality preference diminished and their acceptance of various reasons for privileged treatment increased. It was not until 8 years, however, that they differentiated between legitimate and idiosyncratic reasons for inequality. These findings suggest that children's sense of distributive justice develops from an early equality preference to a more flexible understanding of the basic normative reasons that inequality may, in some cases, be just.