Abstract not found

Abstract not found

This paper views lexical acquisition OS a problem of induction: Children must figure out the meaning of a given term, given the large number of possible mean-ings any term could have. If children had to consider, evaluate, and rule out an unlimited number of hypotheses obout each word in order to figure out its mean-ing, learning word meanings would be hopeless. Children must, therefore, be limited in the kinds of hypotheses they consider as possible word meanings. This paper considers three possible constraints on word meanings: (1) The whole object assumption which leads children to interpret navel terms as labels for objects-not parts, substances, or other properties of objects: (2) The taxonomic assumption which leads children to consider labels as referring to objects of like kind, rather than to objects that are thematically related: and (3) The mutual exclusivity assumption which leads children to expect each object to hove only one label. Some of the evidence for these constraints is reviewed. Children acquire the vocabulary of natural languages at remarkable speed. In a carefully documented study of an individual child’s vocabulary acquisi-tion, Dromi (1987) reports a point at which her child began acquiring new vocabulary at the rate of 45 words a week. This fits with calculations re-ported by Carey (1978): by age six children have learned 9,000-14,000 words which works out to roughly nine new words a day from about 18 months on. It is still largely a mystery as to how children acquire language at this astonishing rate. A traditional explanation for how children form categories and acquire category terms was to assume a kind of general, all-purpose, inductive mechanism. Inhelder and Piaget (1964) and Bruner, Olver, and Greenfield (1966) implicitly held some form of this model. This view about how cate-gories are acquired contains many implicit assumptions about the nature of categories, about the way in which they are learned, and about how chil-dren’s abilities to categorize change with development (for a discussion of

Human listeners can keep track of statistical regularities among temporally adjacent elements in both speech and musical streams. However, for speech streams, when statistical regularities occur among nonadjacent elements, only certain types of patterns are acquired. Here, using musical tone sequences, the authors investigate nonadjacent learning. When the elements were all similar in pitch range and timbre, learners acquired moderate regularities among adjacent tones but did not acquire highly consistent regularities among nonadjacent tones. However, when elements differed in pitch range or timbre, learners acquired statistical regularities among the similar, but temporally nonadjacent, elements. Finally, with a moderate grouping cue, both adjacent and nonadjacent statistics were learned, indicating that statistical learning is governed not only by temporal adjacency but also by Gestalt principles of similarity. How do listeners organize and learn a patterned sequence of elements? Recent studies of a mechanism we have called statistical learning have shown that adults, young children, and infants are capable of computing transitional probabilities among adjacent syllables in rapidly presented streams of speech and of using these statistics to group syllables into word-like units (Aslin, Saffran, &

Complex words consist of morphemic subunits that can recombine to form other words. Thus midnight is standardly analyzed as consisting of the prefix mid- and stem night, which also occur in words such as midstream and nightly. A considerable body of empirical and theoretical research suggests that morphological structure governs the representation of words in memory and that many words are decomposed into morphological components in processing. We investigated an alternative approach in which morphology arises from the interaction of semantic, phonological, and orthographic codes. Five cross-modal lexical decision experiments show that the magnitude of priming (e.g., for pairs such as teacher-teach) is affected by the degree of semantic and phonological overlap between words. Crucially, items that are only moderately similar produce intermediate facilitation effects (e.g., latelylate) . This pattern is observed both for words standardly treated as morphologically related (e.g., teacher-teach) and for morphologically unrelated words that exhibit similar degrees of semantic and phonological overlap (e.g., snarl-sneer). The results can be understood in terms of connectionist models employing distributed representations rather than discrete morphemes. Graded semantic and phonological similarity effects in priming: Evidence for a distributed connectionist approach to morphology One of the fundamental problems in the study of language is to characterize knowledge of words and how this knowledge is used in comprehension and production. The focus of the present article is on derivational morphology, the aspect of lexical knowledge concerning the structure and formation of complex words. Words such as baker and talking appear to consist of components, traditionally called m...

Previous research has shown that, for learners to fully acquire a miniature phrase structure language, the language must contain cues to the phrases—for example, prosodic grouping or morphological agreement of the words within a phrase (Morgan, Meier, & Newport, 1987, 1989). Research on word segmentation has shown that learners can use transitional probabilities between syllables to segment speech into word-like units (Saffran, Aslin, & Newport, 1996). In the present research, we combine and extend these two sets of findings, asking whether learners can use transitional probabilities between words (or word classes) to segment sentences into phrases, and use this phrasal information to fully acquire the syntax of a miniature language. Adult subjects were exposed to sentences from a miniature language. A pattern in the transitional probabilities between words—high within phrases, low at phrase boundaries—was created by adding syntactic properties that are widespread in natural languages: optional phrases, repeated phrases, moved phrases, different-sized form classes, or all four properties combined. All conditions outperformed controls in learning the language. The best learning occurred with all properties combined, despite the fact that this language was the most complex. These data address the important question of how language learning is successful in the face of the massive complexity of natural languages. In our experiments, learning got better, not worse, when properly structured complexity was added to a language. The results also show that the same type of statistical computation useful in word segmentation might be used as well in learning syntax, suggesting that the range of statistics needed for acquiring various types of structure in natural languages might be suitably small. Correspondence should be addressed to Susan P. Thompson, Department of Psychology, 205

Children aged 8 through 11 ( N � 250) were given a word-by-word sentence task in both the visual and auditory modes. The sentences included an object relative clause, a subject relative clause, or a conjoined verb phrase. Each sentence was followed by a true–false question, testing the subject of either the first or second verb. Participants were also given two memory span measures: digit span and reading span. High digit span children slowed down more at the transition from the main to the relative clause than did the low digit span children. The findings suggest the presence of a U-shaped learning pattern for on-line processing of restrictive relative clauses. Off-line accuracy scores showed different patterns for good comprehenders and poor comprehenders. Poor comprehenders answered the second verb questions at levels that were consistently below chance. Their answers were based on an incorrect local attachment strategy that treated the second noun as the subject of the second verb. For example, they often answered yes to the question “The girl chases the policeman” after the object relative sentence “The boy that the girl sees chases the policeman. ” Interestingly, low memory span poor comprehenders used the local attachment strategy less consistently than high memory span poor comprehenders, and all poor comprehenders used this strategy less consistently for harder than for easier sentences.

One of the great challenges in linguistics and cognitive science is to understand the nature of the mental representation of language. The precise mechanisms of the mind are unknown, but can be modeled through observation and experimentation. By viewing the mind as a computational device that receives input (primary linguistic data) and produces output (the development of grammatical speech) during language acquisition, one can reason about what representations and algorithms must be internal to the learner. In this thesis, I investigate the acquisition of morphology. The principal challenges are how to learn a theory in the presence of sparse data, and in a manner that can provide explanations for the developmental processes in child language acquisition. The main idea underlying this work is that a consideration of the different aspects of language acquisition places strong constraints on cognitively plausible representations and algorithms that are internal to the learner. To develop a model of morphology acquisition, I pursue three lines of work: iv First, I formulate a cognitively-oriented computational framework for studying language acquisition that consists of four components: the linguistic representation, the

WH-questions and the mechanisms of language acquisition, page 2 It is no understatement to say that the central issue in the theory of language acquisition is whether children actually learn language and construct a grammar based on the data to which they are exposed, or whether they set the parameters of an autonomous language acquisition device

Why do languages share structural properties? The functionalist tradition has argued that languages have evolved to suit the needs of their users. By what means functional pressures may come to shape grammar over time, however, remains unknown. Functional pressures could affect adults ’ production; or they could operate during language learning. To date, these possibilities have remained largely untested. We explore the latter possibility, that functional pressures operate during language acquisition. In an artificial language learning experiment we investigate the trade-off between word order and case. Flexible word order languages are potentially ambiguous if no case-marking (or other cues) are employed to identify the doer of the action. We explore whether language learners are biased against uncertainty in the mapping of form and meaning, showing a tendency to make word order a stronger cue to the intended meaning in no-case languages.