Ken Springer

Wayfinding on Foot From Information in Retinal, Not Optical, Flow

People find their way through cluttered environments with ease and without injury. How do they do it? Two approaches to wayfinding are considered: Differential motion parallax (DMP) is a retinal motion invariant of near and far objects moving against fixation; the information in optical flow (IOF) is a radial pattern of vectors, relying on decomposition of retinal flow. Evidence is presented that DMP guides wayfinding during natural gait, accounting for errors as well as correct responses. Evidence against IOF is also presented, and a space-time aliasing artifact that can contaminate IOF displays is explored. Finally, DMP and IOF are separated, showing they can yield different results in different environments. Thus, it is concluded that (a) DMP and IOF are different, (b) DMP and not IOF is used for wayfinding, (c) moving observers do not usually decompose retinal flow, and (d) optical flow may be a mathematical fiction with no psychological reality.

On the development of biologically specific beliefs: the case of inheritance

5 experiments investigated childrens intuitions about genetic transmission of features. After parent animals possessing an abnormal feature were described, children were asked whether their baby would be born with that feature in abnormal or normal form. Features were either internal or external, inborn or acquired after birth, and had functional or nonfunctional consequences for the parents. Among preschoolers, features with functional consequences were considered inherited much more frequently than any other type, but only when the functional consequences were biological rather than social or psychological. Older children demonstrated more awareness of the inheritance of inborn traits. Overall, the results suggest young children have principled, specifically biological notions of inheritance.

Early beliefs about the cause of illness: Evidence against immanent justice

Two experiments evaluated the frequently reported claim that young children consider illness a form of punishment for misdeeds, or immanent justice . Most preschoolers in these experiments rejected the possibility of immanent justice, preferring instead the idea that illness results from contact with contaminants such as germs. Of the children who appeared to believe in immanent justice (e.g., by assenting that eating a stolen apple can make someone sick), many had been making assumptions about material contamination (e.g., the original owner was sick and contaminated the apple). Overall, children were more likely than adults to consider mild forms of contamination harmful. The results of these experiments are consistent with recent demonstrations of sophistication in early reasoning about biological phenomena.

Nonverbal bases of social perception: Developmental change in sensitivity to patterns of motion that reveal interpersonal events

This study examined the development of sensitivity to specific patterns of movement that reveal interpersonal events. Preschoolers and adults viewed an animated film created by Heider and Simmel (1944), and then answered a set of probe questions about traits, emotions, and relationships that characterized the geometric figures in the film. Five-year-olds and adults gained similiar impressions of the film, and their attributions were similar to those that have emerged in open-ended descriptions of the film produced by adults in other experiments. The responses of 4-year-olds diverged from this pattern, as did, to a greater extent, the responses of 3-year-olds. The results were interpreted as supporting the view that sensitivity to patterns of motion that reveal interpersonal events emerges gradually during the late preschool years.

Perceptual boundedness and perceptual support in conceptual development.

A theoretical framework for describing the role of perceptual information in early conceptual development is presented. In the main section of the article, a general operationalization of perceptual boundedness is introduced, 3 causes of this limitation are identified, the conditions under which infants and children seem to be perceptually bound are formulated, and the mechanisms by which this limitation declines are described. Traditional claims that young children are perceptually bound, as well as contemporary objections to these claims, are often based on the assumption that perceptual information is generally unveridical or insufficient. Recent doubts about this assumption are evaluated in the final section of the article. It is concluded that although realist arguments are untenable, there are limited forms of perceptual support for conceptual development.

Early understanding of age- and environment-related noxiousness in biological kinds: Evidence for a naive theory

Abstract Four experiments evaluated whether children have a naive theory in which biological kinds, specifically foods, are distinguished by potential for decomposition. In the first two experiments, 4- through 6-year-olds judged that natural changes such as aging make biological natural kinds (BNK; e.g., apple) noxious, but do not have a comparable effect on nonbiological natural kinds (e.g., rock) or artifacts. In Experiment 3, few children were able to articulate specific biological mechanisms responsible for perceptible signs of noxiousness. But most children in Experiment 4 exhibited the more general understanding that the processes by which BNK become noxious are irreversible. In sum, young children seem to have a domain-specific theory of biological kinds, although they are unaware of the exact mechanisms operative in the domain. Children may thus develop a theory that picks out a domain of objects before the causal principles organizing this domain are fully understood.

The relation between syllable number and visual complexity in the acquisition of word meanings

Four experiments were conducted to explore the correlation between syllable number and visual complexity in the acquisition of novel words. In the first experiment, adult English speakers invented nonsense words as names for random polygons differing in visual complexity. Visually simple polygons received names containing fewer syllables than visually complex polygons did. In addition, analyses of English word-object pairings indicated that a significant correlation between syllable number and visual complexity exists in the English lexicon. In Experiments 2 and 3, adult English speakers matched monosyllabic novel words more often than trisyllabic novel words with visually simple objects, whereas trisyllabic matches were more common for visually complex objects. Experiment 4 replicated these findings with children, indicating that the assumption of a correlation between word and visual complexity exists during the period of intense vocabulary growth. Although the actual correlation between syllable number and visual complexity is small, other posited constraints on word meaning are also limited in strength. However, an increasing number of small, language-specific word-meaning correlations are being uncovered-Given the documented ability of speakers to detect and use these subtle correlations, we argue that a more fruitful approach to word-meaning acquisition would forgo the search for a few broad, powerful word-meaning constraints, and we attempt to uncover individually weak, but perhaps jointly powerful word-meaning correspondences.