The authors examine recent theoretical perspectives of the development of the animate-inanimate distinction in infancy. From these theoretical views emerge 7 characteristic properties, each related to physical or psychological causality, that distinguish animates from inanimates. The literature is reviewed for evidence of infants' ability to perceive and understand each of these properties. Infants associate some animate properties with people by 6 months, but they do not associate the appropriate properties to the broad category of animates and inanimates until at least the middle of the 2nd year. The authors offer a theoretical proposal whereby infants acquire knowledge about the properties of different object kinds through a sensitive perceptual system and a domain general associative learning mechanism that extracts correlations among dynamic and static features.

Two experiments involving object-manipulation tasks were performed to examine whether 1-to 2-year-olds form superordinate-like categories by attending to object parts. In Study 1, 14-, 18-, and 22-month-olds were tested with contrasts of animals, furniture, insects, and vehicles. Fourteen-and 18-month-olds behaved systematically toward categories with different parts (legs or wheels) but not toward categories with matching parts (legs or legs). In Study 2, infants were tested with novel animals and vehicles generated by removing or attaching legs or wheels. In the absence of part differences, all three age groups failed to form superordinate categories. The two younger groups chose to categorize by parts (i.e., legs or wheels) rather than by category membership (animal or vehicle). The results suggest a perceptual basis for categorization whereby infants form dynamic categories, on-line, that are based on the characteristics of the input.It is a common assumption that the categories formed in early childhood fall into one of the three hierarchical classes proposed by Rosch and her colleagues (e.g., Mervis & Rosch, 1981;Rosch, Mervis, Gray, Johnson, & Boyes-Braem, 1976). According to Rosch, the categories that are developmentally primary are at the basic level, with categories developing subsequently at the more general, superordinate level. This developmental sequence is thought to occur because basic-level categories have a high level of within-category similarity and between-category dissimilarity, whereas superordinate categories have low within-category similarity. Thus, it is held that infants form categories of objects that are alike, such as dogs, cats, cars, and chairs, more easily than they form categories that include objects that vary in appearance, such as animals, vehicles, and fumiture. Rosch (1978) referred to these categories as taxonomies, by which she meant that their members are the same kind of thing or are "related to one another by means of class inclusion" (p. 27).A corollary for this assumption is that infants require knowledge beyond information given in the perceptual input to form David H. Rakison and George E. Butterworth, Department of Psychology, University of Sussex, Brighton, England.This work was submitted by David H. Rakison in partial fulfilment of the requirements for the D.Phil. in psychology at the University of Sussex. We express thanks to Colin Crook and Tony Stubbens for their help in video recording and stimulus creation. We also thank Alexandra Campbell for her help with coding and Brenda Todd for her input in this research and comments on a draft of this article.The results of Experiment 1 were presented at the Meeting of the European Science Foundation, San Felui de Guixols, Spain, April 1996, and the results of Experiment 2 were presented at the Annual Meeting of the British Psychological Society Conference, Brighton, England, April 1995.Correspondence concerning this article should be addressed to David H. Rakison, who is now at the Department of Psychology, Mezes 3...

No abstract

In addition to having communicative functions, verbal labels may play a role in shaping concepts. Two experiments assessed whether the presence of labels affected category formation. Subjects learned to categorize "aliens" as those to be approached or those to be avoided. After accuracy feedback on each response was provided, a nonsense label was either presented or not. Providing nonsense category labels facilitated category learning even though the labels were redundant and all subjects had equivalent experience with supervised categorization of the stimuli. A follow-up study investigated differences between learning verbal and nonverbal associations and showed that learning a nonverbal association did not facilitate categorization. The findings show that labels make category distinctions more concrete and bear directly on the language-and-thought debate.

No abstract

Four experiments utilizing the habituation procedure examined 10- to 18-month-olds' ability to detect and encode correlations among features in a motion event (N = 136). Infants were habituated to two events in which objects-with distinct parts and a distinct body-moved across a screen along a rectilinear or curvilinear motion path. Infants were then tested with one familiar event and three events in which one feature of the object (parts, body, or motion path) was presented in a novel combination with the other features. The results of the experiments revealed that 10-month-olds process independently static features in an event, but do not process correlations among dynamic features; whereas 14-month-olds detect the correlation between an object's parts and its motion trajectory, but only when the movement of parts is correlated with the motion of the object. Further, the data show that 18-month-olds detect correlations between all three features when the parts of the object move, but they detect only the relation between parts and motion path when the parts do not move. It is proposed that infants develop representations for the static and dynamic properties of objects through a sensitive perceptual system that detects individual features, whole objects, and movement properties, and a domain-general associative learning mechanism that encodes independent features and correlations among features.

Previous research has established that infants are unable to perceive causality until 6¼ months of age. The current experiments examined whether infants' ability to engage in causal action could facilitate causal perception prior to this age. In Experiment 1, 4½-month-olds were randomly assigned to engage in causal action experience via Velcro sticky mittens or not engage in causal action because they wore non-sticky mittens. Both groups were then tested in the visual habituation paradigm to assess their causal perception. Infants who engaged in causal action - but not those without this causal action experience - perceived the habituation events as causal. Experiment 2 used a similar design to establish that 4½-month-olds are unable to generalize their own causal action to causality observed in dissimilar objects. These data are the first to demonstrate that infants under 6 months of age can perceive causality, and have implications for the mechanisms underlying the development of causal perception.

No abstract