Selectional constraints are limitations on the applicability of predicates to arguments. For example, the statement “The number two is blue” may be syntactically well formed, but at some level it is anomalous — BLUE is not a predicate that can be applied to numbers. According to the influential theory of (Katz and Fodor, 1964), a predicate associates a set of defining features with each argument, expressed within a restricted semantic vocabulary. Despite the persistence of this theory, however, there is widespread agreement about its empirical shortcomings (McCawley, 1968; Fodor, 1977). As an alternative, some critics of the Katz-Fodor theory (e.g. (Johnson-Laird, 1983)) have abandoned the treatment of selectional constraints as semantic, instead treating them as indistinguishable from inferences made on the basis of factual knowledge. This provides a better match for the empirical phenomena, but it opens up a different problem: if selectional constraints are the same as inferences in general, then accounting for them will require a much more complete understanding of knowledge representation and inference than we have at present. The problem, then, is this: how can a theory of selectional constraints be elaborated without first having either an empirically adequate theory of defining features or a comprehensive theory of inference? In this dissertation, I suggest that an answer to this question lies in the representation of conceptual

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MacWhinney (1978) presented a computational model of the acquisition of morphophonology. The present chapter attempts to extend the model presented in that earlier paper to the acquisition of word-order patterns. This extension is supported by an examination of the previous research on syntactic acquisition. In the final section of the chapter, further possible extensions to phonology and semantics are considered. The crucial claim underlying the basic approach to both morphophonology and syntax is that use of a given rule system is governed by a system of alternative strategies. Within such a multileveled model, alternative strategies can be compared in terms of their relative complexity. In the present chapter, these alternative strategies are evaluated through application of the following analytic technique: 1. A relatively simple strategy that can account for at least some of the observed data is presented. 2. It is shown that there are at least some data that are best explained by this strategy. 3. It is shown that, at some point in development, the child produces forms that cannot be explained by this simple strategy alone. 4. A strategy of somewhat greater complexity and power is introduced and it is shown that this strategy can account for at least some of the data not explained by the simpler (and weaker) strategy. This line of argumentation proceeds until evidence has been presented for six alternative strategies in word-order processing.

This monograph discusses research, theory, and practice relevant to how children learn to read English. After an initial overview of writing systems, the discussion summarizes research from developmental psychology on children's language competency when they enter school and on the nature of early reading development. Subsequent sections review theories of learning to read, the characteristics of children who do not learn to read (i.e., who have developmental dyslexia), research from cognitive psychology and cognitive neuroscience on skilled reading, and connectionist models of learning to read. The implications of the research findings for learning to read and teaching reading are discussed. Next, the primary methods used to teach reading (phonics and whole language) are summarized. The final section reviews laboratory and classroom studies on teaching reading. From these different sources of evidence, two inescapable conclusions emerge: (a) Mastering the alphabetic principle (that written symbols are associated with phonemes) is essential to becoming proficient in the skill of reading, and (b) methods that teach this principle directly are more effective than those that do not (especially for children who are at risk in some way for having difficulty learning to read). Using whole-language activities to supplement phonics instruction does help make reading fun and meaningful for children, but ultimately, phonics instruction is critically important because it helps beginning readers understand the alphabetic principle and learn new words. Thus, elementary -school teachers who make the alphabetic principle explicit are most effective in helping their students become skilled, independent readers.

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

“Origins of communicative disorders ” to Elizabeth Bates, and by a grant from the John D. and Catherine T. MacArthur Foundation. We are grateful to Larry Juarez and Meiti Opie The effects of focal brain injury are investigated in the first stages of language development, during the passage from first words to grammar. Parent report and/or free speech data are reported for 53 infants and preschool children between 10- 44 months of age. All children had suffered a single, unilateral brain injury to the left or right hemisphere, incurred before six months of age (usually in the pre- or perinatal period). This is the period in which we should expect to see maximal plasticity, but it is also the period in which the initial specializations of particular cortical regions ought to be most evident. In direct contradiction of hypotheses based on the adult aphasia literature, results from 10- 17 months suggest that children with righthemisphere injuries are at greater risk for delays in word comprehension, and in the gestures that normally precede and accompany language onset. Although there were no differences between left- vs. right-hemisphere injury per se on expressive language, children whose lesions include the left temporal lobe did show significantly greater delays in expressive vocabulary and

To learn a language, the learners must first learn its words, the essential building blocks for utterances. The difficulty in learning words lies in the unavailability of explicit word boundaries in speech input. The learners have to infer lexical items with some innately endowed learning mechanism(s) for regularity detection- regularities in the speech normally indicate word patterns. With respect to Zipf's least-effort principle and Chomsky's thoughts on the minimality of grammar for human language, we hypothesise a cognitive mechanism underlying language learning that seeks for the least-effort representation for input data. Accordingly, lexical learning is to infer the minimal-cost representation for the input under the constraint of permissible representation for lexical items. The main theme of this thesis is to examine how far this learning mechanism can go in unsupervised lexical learning from real language data without any pre-defined (e.g., prosodic and phonotactic) cues, but entirely resting on statistical induction of structural patterns for the most economic representation for the data. We first review

Introduction This research examines how children begin learning the meanings of words. Necessarily, novice word-learners must start by pairing a word form with the scenes in which it occurs, collecting several such pairs, and then identifying the common element in the scenes. Before children have learned many words or any language specific syntax, this extralinguistic context is the only information source they can draw on. However, there has been relatively little research on the details of cross-situational observation. We do not know just how much information is actually available in the extralinguistic contexts of word use. Nor do we know how the properties of this information source might shape what children learn in the initial stages of vocabulary acquisition or the process by which they learn it. The studies that follow begin to address these questions. They focus exclusively on the informational content of the input. They do not explore whether this information is accessible