Breaking the language barrier: an emergentist coalition model for the origins of word learning.

How do children learn their first words? The field of language development has been polarized by responses to this question. Explanations range from constraints/principles accounts that emphasize the importance of cognitive heuristics in language acquisition, to social-pragmatic accounts that highlight the role of parent-child interaction, to associationistic accounts that highlight the role of "dumb attentional mechanisms" in word learning. In this Monograph, an alternative to these accounts is presented: the emergentist coalition theory. A hybrid view of word learning, this theory characterizes lexical acquisition as the emergent product of multiple factors, including cognitive constraints, social-pragmatic factors, and global attentional mechanisms. The model makes three assumptions: (a) that children cull from multiple inputs available for word learning at any given time, (b) that these inputs are differentially weighted over development, and (c) that children develop emergent principles of word learning, which guide subsequent word acquisition. With few exceptions, competing accounts of the word learning process have examined children who are already veteran word learners. By focusing on the very beginnings of word learning at around 12 months of age, however, it is possible to see how social and cognitive factors are coordinated in the process of vocabulary development. After presenting a new method for investigating word learning, the development of reference is used as a test case of the theory. In 12 experiments, with children ranging in age from 12 to 25 months of age, data are described that support the emergentist coalition model. This fundamentally developmental theory posits that children construct principles of word learning. As children's word learning principles emerge and develop, the character of word learning changes over the course of the 2nd year of life.

Lexical principles may underlie the learning of verbs.

To examine whether children (mean age 34 months) can fast map and extend novel action labels to actions for which they do not already have names, the comprehension of familiar and novel verbs was tested using colored drawings of Sesame Street characters performing both familiar and unfamiliar actions. Children were asked to point to the character "verbing," from among sets of 4 drawings. With familiar words and actions, children made correct choices 97% of the time. With novel action words, children performed at levels mostly significantly above chance, selecting a previously unlabeled action or another token of a just-names action. In a second, control experiment children were asked to select an action from among the same sets of 4 drawings, but they were not given a novel action name. Here children mainly demonstrated performance at levels not significantly different from chance, showing that the results from the main experiment were attributable to the presence of a word in the request. Results of these studies are interpreted as support for the availability of principles to ease verb acquisition.

Infants' sensitivity to word boundaries in fluent speech.

Infants' sensitivity to word units in fluent speech was examined by inserting I sec pauses either at boundaries between successive words (Coincident versions) or between syllables within words (Noncoincident versions). In Experiment 1, 24 11-month-olds listened significantly longer to the Coincident versions. In Experiment 2, 24 four-and-a-half- and 24 nine-month-olds did not exhibit the preference for the Coincident versions that the 11-month-olds showed. When the stimuli were low-pass filtered in Experiment 3, 24 11-month-olds showed no preference for the Coincident versions, suggesting they rely on more than prosodic cues. New stimulus materials in Experiment 4 indicated that responses by 24 11-month-olds to the Coincident and Noncoindent versions did not depend solely on prior familiarity with the targets. Two groups of 30 11-month-olds tested in Experiment 5 were as sensitive to groups of 30 11-month-olds tested in Experiment 5 were as sensitive to boundaries for Strong/Weak words as for Weak/Strong words. Taken together, the results suggest that, by 11 months, infants are sensitive to word boundaries in fluent speech, and that this sensitivity depends on more than just prosodic information or prior knowledge of the words.

Early object labels: the case for a developmental lexical principles framework.

Universally, object names make up the largest proportion of any word type found in children's early lexicons. Here we present and critically evaluate a set of six lexical principles (some previously proposed and some new) for making object label learning a manageable task. Overall, the principles have the effect of reducing the amount of information that language-learning children must consider for what a new word might mean. These principles are constructed by children in a two-tiered developmental sequence, as a function of their sensitivity to linguistic input, contextual information, and social-interactional cues. Thus, the process of lexical acquisition changes as a result of the particular principles a given child has at his or her disposal. For children who have only the principles of the first tier (reference, extendibility, and object scope), word learning has a deliberate and laborious look. The principles of the second tier (categorical scope, novel name-nameless category' or N3C, and conventionality) enable the child to acquire many new labels rapidly. The present unified account is argued to have a number of advantages over treating such principles separately and non-developmentally. Further, the explicit recognition that the acquisition and operation of these principles is influenced by the child's interpretation of both linguistic and non-linguistic input is seen as an advance.

Perception of acoustic correlates of major phrasal units by young infants.

How might young learners parse speech into linguistically relevant units? Sensitivity to prosodic markers of these segments is one possibility. Seven experiments examined infants' sensitivity to acoustic correlates of phrasal units in English. The results suggest that: (a) 9 month olds, but not 6 month olds, are attuned to cues that differentially mark speech that is artificially segmented at linguistically COINCIDENT as opposed to NONCOINCIDENT boundaries (Experiments 1 and 2); (b) the pattern holds across both subject phrases and predicate phrases and across samples of both Child- and Adult-directed speech (Experiments 3, 4, and 7); and (c) both 9 month olds and adults show the sensitivity even when most phonetic information is removed by low-pass filtering (Experiments 5 and (6). Acoustic analyses suggest that pitch changes and in some cases durational changes are potential cues that infants might be using to make their discriminations. These findings are discussed with respect to their implications for theories of language acquisition.

Revealing hidden competencies: a new method for studying language comprehension in children with motor impairments.

Pilot work on a new method to assess language comprehension in children with motor impairments was presented. The paradigm is based on the premise that children will prefer to watch a video event that matches a linguistic stimulus rather than an event that does not match the linguistic stimulus. Two experiments, one on noun comprehension and one on verb comprehension, were conducted on young children having cerebral palsy and other neurological pathology associated with motor deficits. The potential advantages of this method over existing methods to assess language comprehension in handicapped as well as nonhandicapped populations were described.

How the prosodic cues in motherese might assist language learning.

The function of motherese has become a pivotal issue in the language-learning literature. The current research takes the approach of asking whether the prosodic characteristics that are distinctive to motherese could play a special role in facilitating the acquisition of syntax. Hirsh-Pasek, Kemler Nelson, Jusczyk, Cassidy, Druss & Kennedy (1987) showed that infants aged 0;7-0;10 are sensitive to prosodic cues that would help them segment the speech stream into perceptual units that correspond to clauses. The present study shows that infants' sensitivity to segment-marking cues in ongoing speech holds for motherese but not for adult-directed speech. The finding is that, for motherese only, infants orient longer to speech that has been interrupted at clausal boundaries than to matched speech that has been interrupted at within-clause locations. This selective preference indicates that the prosodic qualities of motherese provide infants with cues to units of speech that correspond to grammatical units of language-a potentially fundamental contribution of motherese to the learning of syntax.