John D. Coley

The Importance of Knowing a Dodo Is a Bird: Categories and Inferences in 2-Year-Old Children

A straightened, textured yarn is produced employing an apparatus comprising a crimping means, an entangling means and a heating and tensioning means which heats and applies tension to the crimped and entangled yarn prior to packaging.

Categorization and Reasoning among Tree Experts: Do All Roads Lead to Rome?☆

To what degree do conceptual systems reflect universal patterns of featural covariation in the world (similarity) or universal organizing principles of mind, and to what degree do they reflect specific goals, theories, and beliefs of the categorizer? This question was addressed in experiments concerned with categorization and reasoning among different types of tree experts (e.g., taxonomists, landscape workers, parks maintenance personnel). The results show an intriguing pattern of similarities and differences. Differences in sorting between taxonomists and maintenance workers reflect differences in weighting of morphological features. Landscape workers, in contrast, sort trees into goal-derived categories based on utilitarian concerns. These sorting patterns carry over into category-based reasoning for the taxonomists and maintenance personnel but not the landscape workers. These generalizations interact with taxonomic rank and suggest that the genus (or folk generic) level is relatively and in some cases absolutely privileged. Implications of these findings for theories of categorization are discussed.

The tree of life: Universal and cultural features of folkbiological taxonomies and inductions

Abstract Two parallel studies were performed with members of very different cultures—industrialized American and traditional Itzaj-Mayan—to investigate potential universal and cultural features of folkbiological taxonomies and inductions. Specifically, we examined how individuals organize natural categories into taxonomies, and whether they readily use these taxonomies to make inductions about those categories. The results of the first study indicate that there is a cultural consensus both among Americans and the Itzaj in their taxonomies of local mammal species, and that these taxonomies resemble and depart from a corresponding scientific taxonomy in similar ways. However, cultural differences are also shown, such as a greater differentiation and more ecological considerations in Itzaj taxonomies. In a second study, Americans and the Itzaj used their taxonomies to guide similarity- and typicality-based inductions. These inductions converge and diverge crossculturally and regarding scientific inductions where their respective taxonomies do. These findings reveal some universal features of folkbiological inductions, but they also reveal some cultural features such as diversity-based inductions among Americans, and ecologically based inductions among the Itzaj. Overall, these studies suggest that while building folkbiological taxonomies and using them for folkbiological inductions is a universal competence of human cognition there are also important cultural constraints on that competence.

A relevance theory of induction

A framework theory, organized around the principle of relevance, is proposed for category-based reasoning. According to the relevance principle, people assume that premises are informative with respect to conclusions. This idea leads to the prediction that people will use causal scenarios and property reinforcement strategies in inductive reasoning. These predictions are contrasted with both existing models and normative logic. Judgments of argument strength were gathered in three different countries, and the results showed the importance of both causal scenarios and property reinforcement in categorybased inferences. The relation between the relevance framework and existing models of category-based inductive reasoning is discussed in the light of these findings.

Mapping the mind: Essentialist beliefs in children: The acquisition of concepts and theories

In their first few years of life, children are making sense of the world at two levels at once: at the fine-grained level of everyday object categories (deciding which things are trees and which are dogs and which are cookies), and at a broader level that some have called commonsense “theories.” Both are remarkable achievements. First, consider categorization. If childrens vocabulary is any indication, by the age of 6 they have carved up the world into thousands of distinct categories (Carey, 1978). Many children undergo a vocabulary “explosion” at roughly 18 months of age (Halliday, 1975; McShane, 1980; Nelson, 1973), when the rate of acquisition suddenly rises exponentially. One child studied in detail by Dromi (1987) produced as many as 44 new words in one week, and roughly 340 new words in her first 7 months of speech. No other species acquires symbolic communication at this rate. Even studies that successfully teach apes to acquire sizeable vocabularies in sign language are incomparable, with no noticeable vocabulary explosion (e.g., after more than 4 years of exposure to sign language, Washoe acquired only about 132 signs; Gardner & Gardner, 1989). At around the same time that children learn to classify individual entities and undergo rapid vocabulary growth, they are developing broad systems of belief about the world. Not only do children learn to identify certain objects as “dogs,” but they also learn that dogs belong to the class of animals, and that animals engage in characteristic biological processes such as growth, inheritance, and self-generated movement. Children are learning about physical laws such as gravity, mental states such as dreams, and social relationships within units such as families.

BEYOND LABELING: THE ROLE OF MATERNAL INPUT IN THE ACQUISITION OF RICHLY STRUCTURED CATEGORIES

Recent research shows that preschool children are skilled classifiers, using categories both to organize information efficiently and to extend knowledge beyond what is already known. Moreover, by 2 1/2 years of age, children are sensitive to nonobvious properties of categories and assume that category members share underlying similarities. Why do children expect categories to have this rich structure, and how do children appropriately limit this expectation to certain domains (i.e., animals vs. artifacts)? The present studies explore the role of maternal input, providing one of the first detailed looks at how mothers convey information about category structure during naturalistic interactions. Forty-six mothers and their 20- or 35-month-old children read picture books together. Sessions were videotaped, and the resulting transcripts were coded for explicit and implicit discussion of animal and artifact categories. Sequences of gestures toward pictures were also examined in order to reveal the focus of attention and implicit links. drawn between items. Results indicate that mothers provided a rich array of information beyond simple labeling routines. Taxonomic categories were stressed in subtle and indirect ways, in both speech and gesture, especially for animals. Statements and gestures that linked two pictures were more frequent for taxonomically related animal pictures than for other picture pairs. Mothers also generalized category information using generic noun phrases, again more for animals than for artifacts. However, mothers provided little explicit discussion of nonobvious similarities, underlying properties, or inductive potential among category members. These data suggest possible mechanisms by which a notion of kind is conveyed in the absence of detailed information about category essences.

Cultural and experiential differences in the development of folkbiological induction

Careys (1985) book on conceptual change and the accompanying argument that childrens biology initially is organized in terms of naive psychology has sparked a great detail of research and debate. This body of research on childrens biology has, however, been almost exclusively been based on urban, majority culture children in the US or in other industrialized nations. The development of folkbiological knowledge may depend on cultural and experiential background. If this is the case, then urban majority culture children may prove to be the exception rather than the rule, because plants and animals do not play a significant role in their everyday life. Urban majority culture children, rural majority culture children, and rural Native American (Menominee) children were given a property projection task based on Careys original paradigm. Each group produced a unique profile of development. Only urban children showed evidence for early anthropocentrism, suggesting that the co-mingling of psychology and biology may be a product of an impoverished experience with nature. In comparison to urban majority culture children even the youngest rural children generalized in terms of biological affinity. In addition, all ages of Native American children and the older rural majority culture children (unlike urban children) gave clear evidence of ecological reasoning. These results show that both culture and expertise (exposure to nature) play a role in the development of folkbiological thought.

Tall is typical: central tendency, ideal dimensions, and graded category structure among tree experts and novices.

Many accounts of categorization equate goodness-of-example with central tendency for common taxonomic categories; the best examples of a category are average members#x2014;those that are most similar to most other category members. In the present study, we asked 24 tree experts and 20 novices to rate goodness-of-example for a sample of 48 trees and found (1) that the internal structure of the categorytree differed between novices and experts and (2) that central tendency did not determine goodnessof-example ratings for either group. For novices, familiarity determined goodness-of-example ratings. For experts, the “ideal” dimensions of height and weediness, rather than average similarity to other trees, were the primary predictors of goodness-of-example ratings for experts. The best examples oftree were not species of average height, but of extreme height. The worst examples were the weediest trees. We also found systematic differences in predictors of goodness-of-example as a function of type of expertise. We argue that the internal structure of taxonomic categories can be shaped by goal-related experience and is not necessarily a reflection of the attributional structure of the environment. Implications for models of category structure and category learning are discussed.

Development of categorization and reasoning in the natural world: Novices to experts, naive similarity to ecological knowledge

Two experiments investigate the role of similarity and causal-ecological knowledge in expert and novice categorization and reasoning. In Experiment 1, university undergraduates and commercial fishermen sorted marine creatures into groups; although there was substantial agreement, novices sorted largely on the basis of appearance, whereas experts often cited commercial, ecological, or behavioral factors, and systematically subdivided fish on the basis of ecological niche. In Experiment 2, experts and novices were asked to generalize a blank property or novel disease from a pair of marine creatures. Novices relied on similarity to guide generalizations. Experts used similarity to reason about blank properties but ecological relations to reason about diseases. Expertise appears to involve knowledge of multiple relations among entities and context-sensitive application of those relations.

Why essences are essential in the psychology of concepts

Woo-kyoung Ahn*, Charles Kalish, Susan A. Gelman, Douglas L. Medin, Christian Luhmann, Scott Atran, John D. Coley, Patrick Shafto Department of Psychology, Vanderbilt University, Nashville, TN 37203, USA Department of Educational Psychology, University of Wisconsin, Madison, WI 53706, USA Department of Psychology, University of Michigan, Ann Arbor, MI 48109-1109, USA Department of Psychology, Northwestern University, Evanston, IL 60208-2710, USA Centre National de la Recherche Scientifique, Marseilles, France Department of Psychology, Northeastern University, Boston, MA 02115, USA