Sandra R. Waxman

Early word-learning entails reference, not merely associations

Recent years have witnessed a resurgence of classic tensions concerning the fundamental nature of human knowledge and the processes underlying its acquisition. This tension, especially evident in research on the acquisition of words and concepts, arises when researchers pit one type of content against another (perceptual versus conceptual) and one type of process against another (associative versus theory-based). But these dichotomies are false; they rest upon insufficient consideration of the structure and diversity of the words and concepts that we naturally acquire. As infants and young children establish categories and acquire words to describe them, they take advantage of both perceptual and conceptual information, and relate this to both the (rudimentary) theories they hold and the statistics that they witness.

Words (but not Tones) Facilitate Object Categorization: Evidence From 6- and 12-Month-Olds

Recent studies reveal that naming has powerful conceptual consequences within the first year of life. Naming distinct objects with the same word highlights commonalities among the objects and promotes object categorization. In the present experiment, we pursued the origin of this link by examining the influence of words and tones on object categorization in infants at 6 and 12 months. At both ages, infants hearing a novel word for a set of distinct objects successfully formed object categories; those hearing a sequence of tones for the same objects did not. These results support the view that infants are sensitive to powerful and increasingly nuanced links between linguistic and conceptual units very early in the process of lexical acquisition.

Word learning is 'smart': evidence that conceptual information affects preschoolers' extension of novel words

We examined electrophysiological correlates of conscious change detection versus change blindness for equivalent displays. Observers had to detect any changes, across a visual interruption, between a pair of successive displays. Each display comprised grey circles on a background of alternate black and white stripes. Foreground changes arose when light-grey circles turned dark-grey and vice-versa. Physically stronger background changes arose when all black stripes turned white and vice-versa. Despite their physical strength, background changes were undetected unless attention was directed to them, whereas foreground changes were invariably seen. Event-related potentials revealed that the P300 component was suppressed for unseen background changes, as compared with the same changes when seen. This effect arose first over frontal sites, and then spread to parietal sites. These results extend recent fMRI findings that fronto-parietal activation is associated with conscious visual change detection, to reveal the timing of these neural correlates.

Challenging the Notion of a Thematic Preference in Young Children.

Many researchers have argued that early cognitive development is characterized by a conceptual preference for thematic over taxonomic relations. However, more recent research indicates that infants and toddlers may not favor thematic relations. To resolve this discrepancy, the conceptual preferences of children ranging from 2 to 4 years of age were examined, using a forced-choice task including a target (e.g., a carrot), a thematic alternative (e.g., a rabbit), and a taxonomic alternative (e.g., a tomato). The effects of age, experimenters instructions, hierarchical level (basic vs. superordinate), and stimulus medium (pictures vs. objects) were examined systematically. Children revealed no pervasive preference for either thematic or taxonomic relations. This challenges the notion of a developmental shift in conceptual preferences and suggests a more continuous trajectory in early conceptual development.

Categorization in 3- and 4-Month-Old Infants: An Advantage of Words Over Tones

Neonates prefer human speech to other nonlinguistic auditory stimuli. However, it remains an open question whether there are any conceptual consequences of words on object categorization in infants younger than 6 months. The current study examined the influence of words and tones on object categorization in forty-six 3- to 4-month-old infants. Infants were familiarized to different exemplars of a category accompanied by either a labeling phrase or a tone sequence. In test, infants viewed novel category and new within-category exemplars. Infants who heard labeling phrases provided evidence of categorization at test while infants who heard tone sequences did not, suggesting that infants as young as 3 months of age treat words and tones differently vis-à-vis object categorization.

The Role of Comparison in the Extension of Novel Adjectives

Previous reseach has documented that basic-level object categories provide an initial foundation for mapping adjectives to object properties. Children ranging from 21 months to 3 years can successfully extend a novel adjective (e.g., transparent) to other objects sharing a salient property if the objects are all members of the same basic-level category; if the objects are members of different basic-level categories, they fail to extend adjectives systematically (R. S. Klibanoff & S. R. Waxman, 2000a; S. R. Waxman & D. B. Markow, 1998). The present study proposed that the process of comparison is instrumental in childrens ability to move beyond this foundation. To promote comparison, 2 target objects were introduced to 3-year-olds. In Experiment 1, the targets had contrastive properties (e.g., 1 transparent and 1 opaque object); in Experiment 2, the targets had consistent properties (e.g., 2 transparent objects). The results of both experiments illustrate that comparison--a general psychological process--operates in conjunction with naming to support the extension of novel adjectives to properties of objects from diverse basic-level categories.

The origins and evolution of links between word learning and conceptual organization: new evidence from 11-month-olds

How do infants map words to their meaning? How do they discover that different types of words (e.g. noun, adjective) refer to different aspects of the same objects (e.g. category, property)? We have proposed that (1) infants begin with a broad expectation that novel open-class words (both nouns and adjectives) highlight commonalities (both category- and property-based) among objects, and that (2) this initial expectation is subsequently fine-tuned through linguistic experience. We examine the first part of this proposal, asking whether 11-month-old infants can construe the very same set of objects (e.g. four purple animals) either as members of an object category (e.g. animals) or as embodying a salient object property (e.g. four purple things), and whether naming (with count nouns vs. adjectives) differentially influences their construals. Results support the proposal. Infants treated novel nouns and adjectives identically, mapping both types of words to both category- and property-based commonalities among objects.

Principles that are invoked in the acquisition of words, but not facts

A controversial question is whether language acquisition is the result of domain-general or domain-specific principles. Focusing on word-learning, Markson and Bloom (Nature 385(6619) (1997) 813) recently argued that the ability to learn and retain new words (count nouns) is the result of abilities that are not specific to language. In the current experiment, we replicate their empirical finding, but challenge their domain-general interpretation by highlighting a crucial distinction between the principles involved in learning a count noun, as compared to learning a fact. The current results confirm that learning count nouns and facts involve (at least) two common components: establishing a mapping to a designated individual, and retaining this mapping over time. However, these results go further to document that the processes invoked in the acquisition of words differ from those invoked in the acquisition of facts. Children spontaneously and systematically extended a novel count noun exclusively to other members of the same category, but revealed no such systematicity when extending a fact. This illustrates that there are principles that are invoked in learning a novel count noun that are not invoked in learning a fact.

Beyond the basics: Preschool children label objects flexibly at multiple hierarchical levels.

Although preschoolers typically accept the basic level label for an object (e.g. dog) and tend to resist all others (e.g. collie, animal), this tendency is not inviolable. Under certain circumstances, children accept more than one label per object. In this experiment, with 20 three- and 20 four-year-old children, we extended this body of research in three ways. We examined (I) childrens production of multiple, hierarchically related labels; (2) the pragmatic consequences of the inherent asymmetry of inclusion relations; and (3) the influence of morphology (modifier+noun constructions vs. simple lexemes) at the subordinate level. Children labelled objects most frequently at the basic level, but also readily produced many non-basic level terms. Children, like adults, may prefer to label objects at the basic level, but they exhibit no general prohibition against also labelling at other, non-basic levels. Their performance challenges the notion that the ability to label objects flexibly at multiple levels is beyond the young childs capacity.

Relations among Word Meanings in Early Lexical Development.

When deriving the meanings of individual words, children must also discern the relations among words. To ascertain how children interpret such relations, we taught twelve 2-year-olds novel count nouns for related but unfamiliar objects. Although we never specified the relations among words, childrens interpretation of the relations was mediated by the similarity of the objects. For dissimilar objects, children interpreted the words as mutually exclusive. For more similar objects, childrens performance was consistent with a hierarchical interpretation of meaning. Thus, by 2 years of age, children have the conceptual and lexical abilities necessary for the establishment of hierarchical inclusion relations. The significance of this finding for theories of lexical and conceptual development is discussed.