Learning nouns and adjectives a connectionist account

Why do children learn nouns such as cup faster than dimensional adjectives such as big? Most explanations of this phenomenon rely on prior knowledge of the noun-adjective distinction or on the logical priority of nouns as the arguments of predicates. In th

Learning Nouns and Adjectives: A Connectionist AccountMichael Gasser Computer Science and Linguistics Departments Lindley Hall 215 Indiana University Bloomington, IN 47405, USAgasser@indiana.edu

Linda B. Smith Psychology Department Psychology 332 Indiana University Bloomington, IN 47405, USAsmith4@indiana.edu

Why do children learn nouns such as cup faster than dimensional adjectives such as big? Most explanations of this phenomenon rely on prior knowledge of the noun-adjective distinction or on the logical priority of nouns as the arguments of predicates. In this paper we examine an alternative account, one which relies instead on properties of the semantic categories to be learned and of the word learning task itself. We isolate four such properties: the relative size, the relative compactness, and the degree of overlap of the regions in representational space associated with the categories and the presence or absence of lexical dimensions (what color? ) in the linguistic context of a word. In a set of ve experiments, we trained a simple connectionist network to label input objects in particular linguistic contexts. The network learned categories resembling nouns with respect to the four properties faster than it learned categories resembling adjectives.

Abstract

Young children learn nouns more rapidly and less errorfully than they learn adjectives. The nouns that children so readily learn typically label concrete things such as BLOCK1 and DOG. The adjectives that young children learn with greater di culty label the perceptible properties of these same objects, for example, RED and WET. Why are concrete nouns easier for young children to learn than dimensional adjectives?1

To whom correspondence should be addressed We will use uppercase for concepts, italics for linguistic forms, and double quotes for utterances.

Why do children learn nouns such as cup faster than dimensional adjectives such as big? Most explanations of this phenomenon rely on prior knowledge of the noun-adjective distinction or on the logical priority of nouns as the arguments of predicates. In th

It is common in the study of cognitive development to explain such di erences in learning by positing domain-speci c mechanisms dedicated to that learning. Thus one might explain the noun advantage by looking for conceptual structures that speci cally constrain or promote the learning of nouns and the lack of such speci c structures for adjectives. In this paper, we pursue an alternate idea. We propose that common nouns and dimensional adjectives are initially acquired by the very same processes in the very same way. But, we argue, many mundane factors conspire to make names for common things more easily learned than labels for the properties of those things. We test our account by examining how a general category learning device, a multi-layer feedforward connectionist network, learns concrete nouns and dimensional adjectives.

1 The PhenomenonThree kinds of evidence point to the initial priority of names for things over labels for the attributes of those same things. The rst concerns the kinds of words that comprise early productive vocabularies. Nouns dominate; dimensional adjectives are rare or nonexistent. For examp

le, in Stern's diary study of the acquisition of English (Gentner, 1978), 78% of the words produced at 20 months were nouns while none were adjectives. Similarly, in Nelson's (1973) study of 18 children learning English, fewer than 7% of the rst 50 words were adjectives. The priority of nouns over adjectives in early vocabularies is evident in other languages as well. In Dromi's (1987) study of one child learning Hebrew, only 4 of the rst 337 words were adjectives. In a longitudinal study of the acquisition of Spanish by 328 children, Jackson-Maldonado et al. (1993) found only one adjective among the 88 most common words. The nding that adjectives are infrequent in early vocabularies is remarkable given that common dimensional adjectives such as size and color terms are among the most frequently used words in adult language. The second class of evidence concerns studies of arti cial word learning. In this commonly used method, experimenters present a novel object to a child and label it with a novel word (e.g.,\this is a dax"). Children's interpretation of the word is measured by the kinds of other objects to which they generalize the newly learned label. Considerable evidence indicates that by 18 months (and quite possibly before), children interpret novel nouns as referring to taxonomic categories (Markman, 1989; Waxman, 1994). Further, the evidence suggests that children remember what they have learned over several days and weeks (Woodward, Markman,& Fitzsimmons, 1994). There have been a number of attempts to use these methods to teach novel adjectives. In these studies, the novel word is placed in an adjectival context (e.g.,\this is a daxy one") or is explicitly contrasted with a known adjective (e.g.,\this is ecru, not red"). Learning in these instances has proved modest at best, even in children as old as 36 months (Au& Laframboise, 1990; Au& Markman, 1987; Carey, 1978; Smith, Jones,& Landau, 1992; Taylor& Gelman, 1988). Cross-linguistic studies of arti cial word learning also suggest that names for concrete things are special in early language learning (Imai& Gentner, 1993; Waxman, 1994) in that there are considerable similarities in the nature of children's noun extensions across languages and considerable variability across (and within) languages in young children's interpretation of novel adjectives. Other evidence from children learn …… 此处隐藏：41434字，全部文档内容请下载后查看。喜欢就下载吧 ……