Basic objects in natural categories* 1

Child Development, 1991

Previous research has revealed that novel nouns highlight category relations at superordinate and basic levels but, paradoxically, make subordinate classification more difficult for preschool children. In Experiment 1, we provide additional evidence that novel nouns put 3-year-old children at a disadvantage in subordinate classification. We suggest that this reflects young children's inclination to label and classify objects at the basic level. In Experiments 2 and 3, we identify 2 circumstances under which 3-year-old children alter their basic level expectation. In Experiment 2, we provide children with specific information to distinguish the relevant subclasses. In Experiment 3, we introduce the novel nouns in conjunction with die familiar basic level labels. Under each of" these circumstances, novel nouns do not present an obstacle to subordinate classification. Children's linguistic biases (e.g., die noun-category bias) and their existing knowledge and vocabularies jointly influence early conceptual development. An impressive amount of empirical sup-tual and semantic knowledge in the establishport has been summoned in favor of the argument of new subordinate level categories. ment that certain aspects of human psychological development are guided by implicit Several different research groups have biases or constraints. But it is equally clear reported that when children are learning the that these biases operate in concert with other meaning of a novel word, they do not sample important aspects of development, for chil-randomly among possible meanings, but indren's experiences with people, objects, and stead use subtle information conveyed by events are also essential elements in develop-syntactic form class (e.g., adjectives, nouns, ment (Bruner & Haste, 1987; Callanan, 1985; determiners) to help them assign meaning Vygotsky, 1962). To illustrate this, we take (Brown, 1957; Gelman & Markman, 1985; one particular bias as a case in point. We ex-Gelman & Taylor, 1984; Katz, Baker, & Macamine the ways in which the noun-category namara, 1974; Waxman, 1990). Nouns, in parbias (Markman & Hutchinson, 1984; Waxman ticular, appear to focus children's attention on & Gelman, 1986; Waxman & Kosowski, 1990) taxonomic relations, especially at basic^ and is influenced by children's existing concep-superordinate levels. As a result, children sort This research was supported by grants firom the American Association of University Women, the John D. and Catherine T. MacArthur Foundation, and the Spencer Foundation to die first audior, and by NSF grant BNS 8310009 to the second. Parts of this research were presented in papers entided "Interactions between Existing Knowledge" and "Language in Subordinate Classification" at the meetings of the Society for Research in Child Development, April 1987, Baltimore, Md, and "Angelfish Have Fused Teeth: Interactions between Information and Category Labels in Subordinate Category Development" at the meetings of the Society for Research in Child Development, April 1989, Kansas City. We are grateful to the children, teachers, and parents of the

New directions for child and adolescent development, 2007

1979

This work is concerned with developmental changes in the structure of classifications. The central claim is that young children's undifferentiated perceptions of complex stimuli are highly structured by wholistic similarity whereas older children's perceptions are structured by component dimensions. It is shown in 2 experiments that young children systematically and spontaneously generalize a category if it is well organized by overall similarity but not if it is organized by a criterial dimension.

Cognitive Science, 1985

Support for the prototype theory of categorization was found i n a study of the structure of social categories. Though occupational terms such as DOCTOR are socially defined, they do not have the classical structure their clear definitional origins would predict. Conceptions of social categories are richer and more complex than those of physical object categories and subjects agree upon them. Comparison of various instructions for eliciting attributes of categories showed that whether subjects are asked to define a term, give characteristics, or describe ways they recognize members of categories, the attributes they list contribute to a prototype structure. These data provide evi dence against the view that prototype structure is relevant only to an identification procedure and not to the care of concepts, as has been suggested.

Memory & Cognition, 1991

Natural taxonomies consist of categories that vary in level of abstraction. Categories at the basic level, such as chair and apple, are preferred in a broad range ofsituations (Rosch, Mervis, Gray, Johnson, & Boyes-Broem;. Several studies have revealed qualitative differences between the basic level and other levels. For example, Tversky and Hemenway (1984) presented evidence that parts proliferate at the basic level; they proposed that parts link the appearance of category members with their {unctions. Although not taking issue with these findings, investigated whether parts are necessary or sufficient for a basic level: In an attempt to demonstrate that parts are not necessary, Murphy used artificial stimuli that did not capture the essential features ofnatural taxonomies. These discrepancies preclude any conclusions based on his studies. Murphy's data also do not support his claim that parts are not sufficient for a basic leoel: Finally, it is unlikely that pursuing questions ofnecessity or sufficiency will produce insights into human categorization.

Our experience of the world typically makes us aware of a wide variety of properties of objects, ranging from their color and shape to their identity and function. In this paper, I use the notion of categorization to explore these various forms of awareness. I begin by arguing for a tripartite model of categorization that loosely groups our awareness of the properties of objects into three broad classes, namely low-, mid-, and high-level categorization. I relate this tripartite distinction to the current controversies surrounding the perception-cognition distinction, and argue that, of the three classes of categorization, mid-level categorization is of interest. Roughly, this is the process by which we effortlessly and automatically recognize perceived objects as being of given kinds. I go on to consider the question of whether mid-level categorization is best considered a form of perception or cognition, and examine merits and difficulties associated with either approach. Finally, I explore a more radical approach I term the Three Kinds view that takes mid-level categorization to be best understood as a further process intermediate between perception and cognition.

Cognitive Development, 1988

Cognition, 2005

Four-and-a-half-month-old infants' ðN ¼ 100Þ category formation and use was studied in a series of five experiments. For each experiment, the test events featured a display composed of a cylinder and a box. Previous research showed that this display is not clearly parsed as a single unit or as two separate units by infants of this age. Immediately prior to testing, infants were shown a set of category exemplars. Knowledge about this category could help infants disambiguate the test display, which contained a novel exemplar of this category. Clear interpretation of the test display as composed of two separate units (as indicated by infants' longer looking at the move-together than at the move-apart test event) was taken as evidence of category formation and use. In Experiments 1 and 5, infants' prior experience with a set of three different boxes that were similar to the test box facilitated their segregation of the test display. Experiment 2 showed that three different exemplars are necessary: prior experience with any two of the three boxes used in Experiment 1 did not facilitate infants' segregation of the test display. Experiment 3 showed that variability in the exemplar set is necessary: prior experience with three identical boxes did not facilitate infants' segregation of the test display. Experiment 4 showed that under these conditions of very brief prior exposure, similarity between the exemplar set and test box is necessary: prior experience with three different boxes that were not very similar to the test box did not facilitate infants' segregation of the test display. Together, these findings suggest that: (a) number of exemplars, variability, and similarity in the exemplar set are important for infants' category formation, and (b) infants use their category knowledge to determine the boundaries of the objects in a display. q

The Cambridge Handbook of Psycholinguistics

The literature on concept development is highly contentious because there is a lot at stake. The processes that give rise to categories are at the very core of how we understand human cognition. In broad strokes, the debate is about whether categories reflect internal representations that are highly stable symbolic proposition-like and manipulated via logical operators or, whether they are probabilistic, context-dependent, and derived from bundles of correlated features and ordinary processes of perceiving and remembering (for reviews, see, Komatsu, 1992; Murphy & Medin, 1989; E. Smith, 1989; E. Smith & Medin, 1981. The literature appears to cycle through these two classes of accounts, advancing with each pass through but never quite leaving these two general points of view. Many of the contentious issues in the developmental literature on concepts and categories are variants of this debate. Accordingly, this review begins with a brief history of theories of categories. This is as history of back-and-forth transitions between a focus on more the more stable and the more probabilistic aspects of categories and it is a debate that is not resolved. However, by either view, categories result from internal representations that capture the structure in the world. Accordingly, the review of the developmental literature is organized with respect to recent advances in understanding outside-the-mind factors that organize and recruit the cognitive processes that create categories: the statistical regularities in the learning environment, the cognitive tasks and the nested time scales of the internal processes they recruit, and the body which is the interface between the external world and cognition. Back-and-forth theories.

2004