We investigated whether 1-year-old infants use their shared experience with an adult to determine the meaning of a pointing gesture. In the first study, after two adults had each shared a different activity with the infant, one of the adults pointed to a target object. Eighteen- but not 14-month-olds responded appropriately to the pointing gesture based on the particular activity they had previously shared with that particular adult. In the second study, 14-month-olds were successful in a simpler procedure in which the pointing adult either had or had not shared a relevant activity with the infant prior to the pointing. Infants just beginning to learn language thus already show a complex understanding of the pragmatics of cooperative communication in which shared experience with particular individuals plays a crucial role.

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.

The prototypical word learning situation in western, middle-class cultures is dyadic: an adult addresses a child directly, ideally in a manner sensitive to their current focus of attention. But young children also seem to learn many of their words in polyadic situations through overhearing. Extending the previous work of Akhtar and colleagues, in the current two studies we gave 18-month-old infants opportunities to acquire novel words through overhearing in situations that were a bit more complex: they did not socially interact with the adult who used the new word before the word learning situation began, and the way the adult used the new word was less transparent in that it was neither a naming nor a directive speech act. In both studies, infants learned words equally well (and above chance) whether they were directly addressed or had to eavesdrop on two adults. Almost from the beginning, young children employ diverse learning strategies for acquiring new words.

Human social interaction depends on individuals identifying the common ground they have with others, based both on personally shared experiences and on cultural common ground that all members of the group share. We introduced 3- and 5-year-old children to a culturally well-known object and a novel object. An experimenter then entered and asked, 'What is that?', either as a request for information or in a recognitory way. When she was requesting information, both 3- and 5-year-olds assumed she was asking about the novel object. When she seemed to recognize an object, 5-year-olds assumed she was referring to the culturally well-known object. Thus, by 3 years of age, children are beginning to understand that they share cultural common ground with other members of their group.