This target article presents a theory of human cultural learning. Cultural learning is identified with those instances of social learning in which intersubjectivity or perspective-taking plays a vital role, both in the original learning process and in the resulting cognitive product. Cultural learning manifests itself in three forms during human ontogeny: imitative learning, instructed learning, and collaborative learning – in that order. Evidence is provided that this progression arises from the developmental ordering of the underlying social-cognitive concepts and processes involved. Imitative learning relies on a concept of intentional agent and involves simple perspective-taking. Instructed learning relies on a concept of mental agent and involves alternating/coordinated perspective-taking (intersubjectivity). Collaborative learning relies on a concept of reflective agent and involves integrated perspective-taking (reflective intersubjectivity). A comparison of normal children, autistic children and wild and enculturated chimpanzees provides further evidence for these correlations between social cognition and cultural learning. Cultural learning is a uniquely human form of social learning that allows for a fidelity of transmission of behaviors and information among conspecifics not possible in other forms of social learning, thereby providing the psychological basis for cultural evolution.

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Two studies of verb learning are reported. The focus of both studies was on children in their second year of life learning verbs in various pragmatic contexts. Of particular interest was the comparison of ostensive contexts -in which word and referent were simultaneously present in the child's perceptual field -to non-ostensive contexts. In a naturalistic study of 24 children at i;3 and i;o,, it was found that mothers modelled verbs for their children most often BEFORE the referent action actually occurred. Over 60 % of maternal verbs were used to refer to actions that mothers wished children to perform or that they were anticipating their performing (IMPENDING actions). Some verbs were also used to refer to current actions (ONGOING actions) or actions that had just been completed (COMPLETED actions). Children responded with comprehension most often to impending models. Impending and completed models, but not ongoing models, were correlated with children's verb vocabularies at 1 ;g. The second study was a lexical training study of 48 two-year-olds. Children learned to produce a novel verb best when it was modelled in the impending condition. They learned to comprehend it equally well in the impending and completed conditions. Children showed no signs of superior learning in the ostensive (ongoing) learning context. Results of the two studies are discussed in terms of the different learning processes involved in acquiring nouns and verbs, and, more broadly, in terms of a social-pragmatic view of language acquisition in which the ostensive teaching paradigm is but one of many contexts in which children learn to establish a joint attentional focus with mature language users.

In this study we compared the abilities of chimpanzees and human children to imitatively learn novel actions on objects. Of particular interest were possible differences between chimpanzees raised mostly with conspecifics (mother-reared) and chimpanzees raised in a human-like cultural environment (enculturated). Subjects were thus 3 enculturated and 3 mother-reared chimpanzees, along with 8 18-month-old and 8 30-month-old human children. Each subject was tested over a 2-day period with 16 novel objects. The introduction of each object was preceded by a baseline period in which the subject's natural proclivities toward the object were determined. For 12 objects, a human experimenter demonstrated first a simple and then a complex novel action, instructing the subject in each case to "Do what I do" (chimpanzees were prepared for the task behaviorally as well). For the other 4 objects, demonstration of a single action took place on the first day and the subject's opportunity to imitate was delayed until the second day, 48 hours later. Actions that a subject produced in baseline were excluded from further analysis. For each analyzed action, the subject's behavior was scored as to whether it successfully reproduced (1) the end result of the demonstrated action, and (2) the behavioral means used by the demonstrator. Results showed that in immediate imitation the mother-reared chimpanzees were much poorer imitators than the enculturated chimpanzees and the human children, who did not differ from one another. Surprisingly, on the delay trials, the enculturated chimpanzees significantly outperformed the other 3 groups. We conclude from these results that a human-like sociocultural environment is an essential component in the development of human-like social-cognitive and imitative learning skills for chimpanzees, and perhaps for human beings as well.

that has not been studied extensively, but which might be expected to differ significantly from previously studied environments, is the linguistic environment of language-learning twins. In particular, differences might be expected to derive from the fact that twins' linguistic interactions with adults are almost always in the presence of a same-age sibling.Twins learn their early language at a slower rate than singleton children (Davis, 1937;Day, 1932; see Savic, 1980, for a review). This difference may be due in part to the different prenatal environments experienced by singletons and twins: twins must share space and nutrition in utero. That this has an effect is evidenced by their lower than average weight at birth (McKeown & Record, 1952). Nevertheless, two recent studies have concluded that the language development of twins is influenced to an even greater extent by their postnatal language learning environments-which they also must share. Conway, Lytton, and Pysh (1980) reported that for their sample of 12 twin dyads maternal speech measures accounted for twice as much of the variance in twin speech complexity as did perinatal status factors such as birthweight and duration of gestation. The mothers in their study produced speech that was less complex, shorter in length, and less frequent in occurrence than that of singleton mothers. Similarly, Lytton, Conway, and Suave (1977) found that, compared to singletons, their 46 twin dyads experienced fewer verbal exchanges of any kind with their parents. Both of these studies concluded that the smaller quantity of speech directed to the twin child was the primary factor contributing to the twins' slower rate of early language development. (See also Bornstein & Ruddy, 1984, for similar results.) Both of these studies of the language learning environment of twins used subjects in their third year of life who were already producing multiword utterances. Recent research on individual differences in early language (reviewed by Nelson, 1981), however, has shown that by the end of the second year of life very important 169 This document is copyrighted by the American Psychological Association or one of its allied publishers.This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.