Category-based induction requires selective use of different relations to guide inferences; this article examines the development of inferences based on ecological relations among living things. Three hundred and forty-six 6-, 8-, and 10-year-old children from rural, suburban, and urban communities projected novel "diseases" or "insides" from one…

Two studies examined how children between ages 4 and 6 use body shape (i.e., the waist-to-hip-ratio [WHR]) for sex categorization. In Study 1 (N = 73), 5- and 6-year-olds, but not 4-year-olds, selected bodies with increasingly discrepant WHRs to be "most like a man" and "most like a woman." Similarly, sex category judgments made by 5- and…

The transition into school occurs at the intersection of multiple environmental settings. This study applied growth curve modeling to a sample of 1,364 American children, followed from birth through age 6, who had been categorized by their exposure to cognitive stimulation at home and in preschool child care and 1st-grade classrooms. Of special…

This study tests the firm distinction children are said to make between living and nonliving kinds. Three, 4-, and 5-year-old children and adults reasoned about whether items that varied on 3 dimensions (alive, face, behavior) had a range of properties (biological, psychological, perceptual, artifact, novel, proper names). Findings demonstrate…

In one of three studies, preschoolers judged that items that shared material properties, such as metal composition, would share dispositional properties, such as corrodibility in water, and that items of the same object type, such as baseball bats, would share functional properties, such as the ability to accelerate a baseball. (BC)

Two experiments tested 10-month-old infants' categorization abilities. Infants were presented with a sequence of stimuli depicting members of a given category. Stimuli representing nonmembers of the category were inserted into the sequence. Infants appeared to disregard the nonmembers in the sequence. (MDM)

A label can convey nonobvious information about category membership. Three studies show that preschoolers (N144) sometimes ignore or reject labels that conflict with appearance, particularly when they are uncertain that the speaker meant to use those labels. In Study 1, 4-year-olds were more reluctant than 3-year-olds to accept that, for example,…

Examines the relationship between class inclusion and age and indicates that class inclusion frequently appears to develop at a much later age than is suggested in Piaget's writings. (Author/MP)

Despite a large body of research demonstrating the kinds of categories to which infants respond, few studies have directly assessed how infants' categorization unfolds over time. Four experiments used a visual familiarization task to evaluate 10-month-old infants' (N=98) learning of exemplars characterized by commonalities in appearance or…

Examined the relationship between two components of class inclusion (hierarchical classification and quantification of inclusion) and investigated the effects of methodological modifications. Subjects were nine girls and nine boys each from first, second, and third grades. (Author/JMB)

Studies children's inductive inferences in order to investigate the development of the expectation that members of a category share unforeseen properties. Results indicate that preschoolers drew more inferences based on category membership than on perceptual appearances. (PCB)

Support for the operation of internal factors in cognitive development was provided by an obtained increase from first to second posttest scores. Two conservations were considered to be involved--conservation of the whole and of the part. (Author)

Three experiments using the familiarization-novelty preference procedure confirmed the hypothesis that three-month-old infants could form categorical representations of spatial relations above and below. The infants, after being shown a familiarization diagram with a dot appearing in multiple locations below a line, showed a preference for a novel…

The ability of 31- to 36-month-old children to act in accordance with rules was assessed in 2 slightly different experiments using sorting tasks and knowledge tasks. Taken together, the results of both experiments imply a relatively rapid, age-related change culminating in the ability to systematically execute rules that require access to extant…

Three studies explored 2- to 4-year-olds' ability to categorize objects based on novel underlying causal power. Children saw that a "blicket" would set off a machine and participated in categorization, induction, and association tasks. Results demonstrated that even 2-year-olds easily learn about an object's new causal power and…