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Biomedical subjects

P M Greenfield

Publications and source records attributed to P M Greenfield.

At least 19 recordsLinked to original sources
PubMed1999

Strategies used to combine seriated cups by chimpanzees (Pan troglodytes), bonobos (Pan paniscus), and capuchins (Cebus apella).

The authors investigated strategies used to combine seriated cups by apes (Pan troglodytes and P. paniscus) and monkeys (Cebus apella) using a protocol reported in P. M. Greenfield, K. Nelson, and E. Saltzman's (1972) study with children. It was hypothesized that apes would exhibit more hierarchical combinations of cups than monkeys, given apes' language capacity, and that apes would seriate the cups more efficiently than monkeys. As predicted, apes made many structures with the cups using a variety of strategies, and monkeys rarely combined the cups. After a training phase to orient monkeys to the task, the 2 genera did not differ in the strategies used to combine the cups or in efficiency in seriating the cups. Success in this task suggests that sensorimotor versions of hierarchically organized combinatorial activity are well within apes' and monkeys' abilities.

Animals↗
PubMed1993

Comparing communicative competence in child and chimp: the pragmatics of repetition.

Through an analysis of chimpanzee-human discourse, we show that two Pan troglodytes chimpanzees and two Pan paniscus chimpanzees (bonobos) exposed to a humanly devised symbol system use partial or complete repetition of others' symbols, as children do: they do not produce rote imitations, but instead use repetition to fulfil a variety of pragmatic functions in discourse. These functions include agreement, request, promise, excitement, and selection from alternatives. In so doing, the chimpanzees demonstrate contingent turn-taking and the use of simple devices for lexical cohesion. In short, they demonstrate conversational competence. Because of the presence of this conversational competence in three sibling species, chimpanzees, bonobos, and humans, it is concluded that the potential to express pragmatic functions through repetition was part of the evolutionary history of human language, present in our common ancestor before the phylogenetic divergence of hominids and chimpanzees. In the context of these similarities, two interesting differences appeared: (I) Human children sometimes used repetition to stimulate more talk in their conversational partner; the chimpanzees, in contrast, use repetition exclusively to forward the non-verbal action. This difference may illuminate a unique feature of human linguistic communication, or it may simply reflect a modality difference (visual symbols used by the chimpanzees, speech used by the children) in the symbol systems considered in this research. A second difference seems likely to reflect a true species difference: utterance length. The one- and two-symbol repetitions used by the chimpanzees to fulfil a variety of pragmatic functions were less than half the maximum length found in either the visual symbol combinations addressed to them by their adult human caregivers or the oral repetitions of two-year-old children. This species difference probably reflects the evolution of increased brain size and consequent increased memory capacity that has occurred since the phylogenetic divergence of hominids and chimpanzees four to seven million years ago.

Animal Communication↗
PubMed1984

Perceived variability and symbol use: a common language-cognition interface in children and chimpanzees (Pan troglodytes).

Analysis of two chimpanzees' conversations with their teacher during a tool-use training task demonstrated that chimps use lexigrams, a humanly devised visual symbol system, selectively to encode perceived variability; that is, they generally used their symbols to differentiate alternative possibilities or to represent change or novelty in a situation. In contrast, they tended to leave unsaid what was unchanging, repetitive, or the unique possibility in a situation. Perceived variability influenced not only which symbols were selected but also utterance length: A single dimension of variability in a situation leads to single-lexigram utterances; multiple dimensions are associated with multi-lexigram utterances. This pattern of results indicates that the absence of formal grammatical structure in chimp language does not imply that utterances beyond one word in length are either rote strings or imitations. The chimps' tendency to mention the variable while leaving the constant or redundant unsaid is, moreover, strong support for the position that their use of a humanly devised symbol system is more than a series of conditioned responses.

Animals↗
PubMed1982

The role of new and old information in the verbal expression of language-disordered children.

The present study used an experimental method to investigate the marking of new and old information in the verbal expression of language-disordered children beyond the one-word stage. The results showed that language-disordered children selectively mark new information in verbal communication, just as normal children do. Language-disordered and normal children, furthermore, manifest the same developmental sequence of strategies for deemphasizing old information--children at an MLU level of 3 tend to omit it, whereas children at an MLU level of 5 tend to pronominalize it. Although both normal and language-disordered children demonstrated the same verbal strategies, a subgroup of language-disordered subjects (over half) pronominalized old information more frequently than normal subjects. These language-disordered subjects demonstrated a proportionately different combination of language features than would be expected at their MLU level.

Child↗
PubMed1978

Some psychological relations between action and language structure.

This study investigated the relationship between complex grammatical structures and complex action sequences. A developmental progression of strategies for combining seriated cups identified in an earlier study (Greenfield et al., 1972) was used to demonstrate some psychological consequences of formal parallels between language and action. The role of grammatical complexity and situational structure in language-action relations was explored. The results have implications for understanding the organization and development of complex action, its control by verbal commands, and the basic processes of speech comprehension.

Adult↗
PubMed1975

The search for structural principles in children's manipulative play: a parallel with linguistic development.

Our study investigated the role of 3 structural principles--hierarchical complexity, interruption, and role change--in the development of children's construction play. The 3 principles are formally parallel to dimensions of language structure. Children from 2 to 6 were required to use varying combinations of structural features in order to build a series of modeled constructions. Predictions about the order of difficulty of our constructions, formulated on the basis of their constituent structural features, were confirmed by the results. Hierarchical complexity and role change, features of "deep structure", added significantly to the difficulty of a construction strategy. Interruption, a "surface-structure" feature, had, in contrast, a minimal effect. The results lend further support to the notion of a cognitive organization common to language and other modes of behavior.

Age Factors↗