Human children 18 – 24 months of age and 3 young chimpanzees interacted in 4 cooperative activities with a human adult partner. The human children successfully participated in cooperative problem-solving activities and social games, whereas the chimpanzees were uninterested in the social games. As an experimental manipulation, in each task the adult partner stopped participating at a specific point during the activity. All children produced at least one communicative attempt to reengage him, perhaps suggesting that they were trying to reinstate a shared goal. No chimpanzee ever made any communicative attempt to reengage the partner. These results are interpreted as evidence for a uniquely human form of cooperative activity involving shared intentionality that emerges in the second year of life. From soon after birth, human infants interact with other persons dyadically in coordinated, turn-taking sequences (Trevarthen, 1979). From about 6 to 9 months of age, infants ’ social interactions become more complex, as they often incorporate outside objects and so become triadic (Tomasello, 1995). Some of these triadic interactions are relatively extended and maintain a turn-taking structure, for example, rolling a ball back and forth or taking turns beating a drum (Gustafson, Green, & West, 1979; Ratner & Bruner, 1978). Most of these early triadic interactionsFsometimes called cooperative gamesFseem to rely on adult scaffolding in fairly ritualized situations, because the introduction of novel toys or a peer partner disrupts them almost totally until 18 months of age (Hay, 1979; Ross, 1982). In a series of longitudinal studies, Eckerman and colleagues have investigated the emergence of young children’s skills in cooperative games of a less ritualized

Two experiments investigated the proclivity of 14-month-old infants (a) to altruistically help others toward individual goals, and (b) to cooperate toward a shared goal. The infants helped another person by handing over objects the other person was unsuccessfully reaching for, but did not help reliably in situations involving more complex goals. When a programmed adult partner interrupted a joint cooperative activity at specific moments, infants sometimes tried to reengage the adult, perhaps indicating that they understood the interdependency of actions toward a shared goal. However, as compared to 18- and 24-month-olds, their skills in behaviorally coordinating their actions with a social partner remained rudimentary. Results are integrated into a model of cooperative activities as they develop over the 2nd year of life. Prosocial behaviors such as helping and cooperation are interesting both cognitively and motivationally: To help someone with a problem, the helper must understand the other’s unachieved goal and possess the altruistic motivation to act on behalf of the other. Whereas in the case of helping, understanding another’s individual goal of action might be sufficient, cooperative activities are based on the formation of a shared goal. That is, two or more persons have to perform interdependent roles directed at a shared goal and possess the motivation to mutually support each other’s action to reach that goal. These kinds of prosocial behaviors are at the core of the human condition. Indeed, humans might act altruistically and cooperate in ways not found in other primates (e.g., Alexander, 1987; Richerson & Boyd, 2005), giving rise to social-cognitive skills such as complex mind reading

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Abstract Helping and cooperation are central to human social life. Here, we report two studies investigating these social behaviors in children with autism and children with developmental delay. In the first study, both groups of children helped the experimenter attain her goals. In the second study, both groups of children cooperated with an adult, but fewer children with autism performed the tasks successfully. When the adult stopped interacting at a certain moment, children with autism produced fewer attempts to re-engage her, possibly indicating that they had not formed a shared goal/shared intentions with her. These results are discussed in terms of the prerequisite cognitive and motivational skills and propensities underlying social behavior.