This paper presents a case study of 3- to 9-year-old children's concepts of size, weight, density, matter, and material kind. Our goal was to examine two claims: (1) that individual concepts undergo differentiation during development; and (2) that young children's concepts are embedded in theory-like structures. To make progress on the first issue, we needed to specify in representational terms what an undifferentiated concept is like and in what sense this undifferentiated concept is a parent of the more differentiated concepts. Our strategy was to use a model of conceptual differentiation suggested by the history of science to guide our search for evidence. In this model, undifferentiated concepts, like differentiated concepts, can be analyzed in terms of their component properties, features, or dimensions. The key difference is that an undifferentiated concept unites certain components which will subsequently be analyzed as components of distinct concepts, and that the undifferentiated concept is embedded in a different theoretical structure from the differentiated concepts. In our study, the same group of 78 children (18 3-year-olds, 18 4-year-olds, 18 5-year-olds, 12 6-7-year-olds, and 12 8-9-year-olds) were given a range of tasks probing their understanding of size, weight, and density; a

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The work upon which this publication is based was performed pursuant to

We introduce a new paradigm for the assessment of auditory and visual categories in 6-month-old infants using a 2-alternative anticipatory eye-movement response. Infants were trained by 2 different methods to anticipate the location of a visual reinforcer

The ability to recall information about the past is thought to emerge in the 2nd half of the 1st year of life. Although there is evidence from both cognitive neuroscience and behavioral psychology to support this hypothesis, there is little longitudinal evidence with which the question can be addressed. Infants' memory abilities were tested between the ages of 9 and 16 months using elicited and deferred imitation. Infants ' memory for events was tested after delays ranging from 1 to 6 months. The results suggest that at 9 months of age, infants are able to store and retrieve representations over delays of as many as 4 weeks but not over long delays. In contrast, 10-month-olds have at their disposal a system that allows encoding and retrieval of event representations over delays of up to 6 months. These results support the idea that the system that underlies long-term ordered recall emerges near the end of the 1st year of life. Memory for the past is fundamental to cognitive function. It is taken virtually for granted by most adults. Developmental changes in this important function have historically been thought to occur only after the end of the infancy period with the emergence of symbolic representational abilities (Piaget, 1951, 1952). Of particular significance is development of the capacity for recall, or the

Environmental spatial abilities are involved in everyday tasks such as finding one’s way in the environment and learning the layout of a new environment. Self-report measures of environmental abilities, e.g., asking people to rate their ‘‘sense of direction (SOD),’ ’ have been found to predict objective measures of these abilities quite highly. In this study, we developed a standardized self-report scale of environmental spatial ability, the Santa Barbara Sense of Direction Scale (SBSOD). The scale proved to be internally consistent and had good test–retest reliability. A series of four validity studies examined its relation to measures of spatial updating and acquisition of spatial knowledge at different scales and acquired from different learning experiences. These studies suggested that the SBSOD is related to tasks that require one to update location in space as a result of self-motion. It is more highly correlated with tests of spatial knowledge that involve orienting oneself within the environment than with tests that involve estimating distances or drawing maps. Self-report SOD is also somewhat more highly correlated with measures of spatial knowledge acquired from direct experience in the environment than with measures of knowledge acquired from maps, video, or virtual environments (VE).

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Most psychometric tests of spatial ability are paper-and-pencil tasks at the bfiguralQ scale of space, in that they involve inspecting, imagining or mentally transforming small shapes or manipulable objects. Environmental spatial tasks, such as wayfinding or learning the layout of a building or city, are carried out in larger spaces that surround the body and involve integration of the sequence of views that change with one’s movement in the environment. In a correlational study, 221 participants were tested on psychometric measures of spatial abilities, spatial updating, verbal abilities and working memory. They also learned the layout of large environments from direct experience walking through a real environment, and via two different media: a desktop virtual environment (VE) and a videotape of a walk through an environment. In an exploratory factor analysis, measures of environmental learning from direct experience defined a separate factor from measures of learning based on VE and video media. In structural-equation models, smallscale spatial abilities predicted performance on the environmental-learning tasks, but were more predictive of learning from media than from direct experience. The results indicate that spatial abilities at different scales of space are partially but not totally dissociated. They specify the degree of overlap between small-scale and large-scale spatial abilities, inform theories of sex differences in these abilities, and provide new insights about what these abilities have in common and how they differ. D 2005 Elsevier Inc. All rights reserved. 1.

Four experiments were conducted to study the use of perspective as a depth cue in infants, using an eye-tracking-system. In the first experiment, no significant difference was observed between the looks for the “normal ” and the “strange ” events on the complete display and at the target in 4-month-olds. In the second experiment, the results of 5-month-olds were similar to those obtained by 4-month-olds but they looked more at the test events when the “strange ” event was presented first. In the third experiment, 5 month-olds were shown a repeated presentation adapted from the “Partial-Lag ” design. Infants ’ exploration of the target indicated that they looked more at the “strange ” event than at the “normal ” event. In the fourth experiment, the same design was used with 4-month-olds but no difference between conditions was observed. Five-month-olds seem to be able to use the perspective cues alone. These different data are discussed.