Amy E. Booth

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.

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.

Socio-Pragmatics and Attention: Contributions to Gesturally Guided Word Learning in Toddlers

It is clear that gestural cues facilitate early word learning. In hopes of illuminating the relative contributions of attentional and socio-pragmatic factors to the mechanisms by which these cues exert their influence, we taught toddlers novel words with the support of a hierarchy of gestural cues. Twenty-eight- to 31-month-olds heard one of two possible referents labeled with a novel word, while the experimenter gazed at or gazed at and pointed to, touched, or manipulated the target. Learning improved with greater redundancy among cues, with the largest improvement evident when pointing was added to gazing. Looking times revealed that attentional factors accounted for only a small fraction of the variance in performance. Indeed, a significant increase in attention driven by manipulation of the target failed to improve learning. The results therefore suggest a strong role for socio-pragmatic factors in supporting the facilitative effect of gestural cues on word learning.

Taking stock as theories of word learning take shape

In this paper we consider the perceptual and conceptual contributions that shape early word learning, using research on the shape bias as a case in point. In our view, conceptual, linguistic, social-pragmatic, and perceptual sources of information influence one another powerfully and continuously in the service of word learning throughout infancy and early childhood. We articulate several key points of convergence and divergence between our theoretical perspective and that of the attentional learning account. Finally, we consider the broader implications of this debate for clarifying the forces that constrain development.

Causal Supports for Early Word Learning

What factors determine whether a young child will learn a new word? Although there are surely numerous contributors, the current investigation highlights the role of causal information. Three-year-old children (N = 36) were taught 6 new words for unfamiliar objects or animals. Items were described in terms of their causal or noncausal properties. When tested only minutes after training, no significant differences between the conditions were evident. However, when tested several days after training, children performed better on words trained in the causal condition. These results demonstrate that the well-documented effect of causal information on learning and categorization extends to word learning in young children.

The Cause of Infant Categorization

We asked whether infants are sensitive to causal relations between objects and outcomes and whether this sensitivity supports categorization. Fourteen- and 18-month-old infants were familiarized with objects from a novel category. For some, the objects caused an electronic toy to activate. For others, the objects were present during activation of the toy, but did not cause the event. For the remaining infants, the events were never activated. Infants were asked to select another category member from a pair of previously unseen objects (one from the familiar, and one from a novel, category). Infants were more likely to select the category match in the causal than the non-causal and no outcome conditions, suggesting that they capitalize on causal information in forming object categories.

Bringing theories of word learning in line with the evidence

Two issues are at stake in this interchange. One concerns the relation between percep-tual, conceptual and linguistic knowledge in early word learning. The other concerns thejudicious treatment of evidence.Briefly stated, we designed our experiments (Booth & Waxman, 2002) with one cleargoal: to document the pervasive role of conceptual information in naming. Three-year-oldchildren in all conditions witnessed the same novel target objects, labeled with the samenovel word (a count noun, e.g. dax). To vary the conceptual status of these named objects,we created brief vignettes that described them either as animate objects (e.g. “…has amommy and daddy who love it very much”) or as artifacts (e.g. “…was made by anastronaut to do a special job on her spaceship”). We examined children’s extension ofthese newly learned words. When the objects were described as artifacts, childrenextended on the basis of shape alone. But when the very same objects were describedas animate objects, children extended on the basis of both shape and texture. Moreover,when we placed eyes (a strong perceptual cue to animacy) on the objects, but describedthem with the artifact vignette, children’s performance was consistent with the artifact,rather than the animate, pattern of word extension. This documents that the conceptualstatus of an individual permeates early word learning, and does so even in the face ofconflicting perceptual cues.It is not surprising that our paper sparked a response from Smith, Jones, Yoshida, andColunga (2003). This work, like that of others (e.g. Bloom, 2000; Gelman & Markman,1987; Gelman & Medin, 1993; Keil, 1994; Kemler Nelson, Russell, Duke, & Jones, 2000;Soja, Carey, & Spelke, 1991; Welder & Graham, 2001), challenges the contention thatword learning can be accounted for by a “…dumb attentional mechanism” (Smith, Jones,

Words Are Not Merely Features: Only Consistently Applied Nouns Guide 4-year-olds' Inferences About Object Categories

Although there is considerable evidence that nouns highlight category-based commonalities, including both those that are perceptually available and those that reflect underlying conceptual similarity, some have claimed that words function merely as features of objects. Here, we directly test these alternative accounts. Four-year-olds (n = 140) were introduced to two different novel animals that were highlighted with nouns, adjectives, or stickers. Children heard a nonobvious novel property applied to the first animal and were asked whether this property applied to other animals that filled the similarity space between the original two animals. When the two animals were named with the same noun, children extended the property broadly throughout the similarity space. When the animals were marked with adjectives or stickers, children adopted a similarity-based pattern. These findings demonstrate clearly that nouns exert a unique effect on categorization—they promote category formation and engage conceptual reasoning beyond perceptual similarity alone.

The facilitative effect of agent-produced motions on categorization in infancy

A tendency to focus on how people manipulate objects, as well as the perceptual correlates of this information, may help infants form categories. Fourteen-month-old infants were given experience with objects from two similar looking categories. The stimuli either remained stationary (Static condition), moved independently in category-specific ways (IM condition), or were moved by visible agents in category-specific ways (APM condition). Infants in the APM condition were more likely to learn, and to learn more rapidly, to differentiate between the categories in a discrimination-learning task, than were infants in the other conditions. Infants who observed category-specific motions produced by the Ex, but were not permitted to reproduce these motions themselves, learned at a rate that fell between that observed in the Static and IM conditions. These effects do not appear to be due to a general attention-enhancing effect of active manipulation.