This study assessed an intersensory redundancy hypothesis, which holds that in early infancy information presented redundantly and in temporal synchrony across two sense modalities selectively recruits attention and facilitates perceptual differentiation more effectively than does the same information presented unimodally. Five-month-old infants' sensitivity to the amodal property of rhythm was examined in 3 experiments. Results revealed that habituation to a bimodal (auditory and visual) rhythm resulted in discrimination of a novel rhythm, whereas habituation to the same rhythm presented unimodally (auditory or visual) resulted in no evidence of discrimination. Also, temporal synchrony between the bimodal auditory and visual information was necessary for rhythm discrimination. These findings support an intersensory redundancy hypothesis and provide further evidence for the importance of redundancy for guiding and constraining early perceptual learning.

There has been a conceptual revolution in the biological sciences over the past several decades. Evidence from genetics, embryology, and developmental biology has converged to offer a more epigenetic, contingent, and dynamic view of how organisms develop. Despite these advances, arguments for the heuristic value of a gene-centered, predeterministic approach to the study of human behavior and development have become increasingly evident in the psychological sciences during this time. In this article, the authors review recent advances in genetics, embryology, and developmental biology that have transformed contemporary developmental and evolutionary theory and explore how these advances challenge gene-centered explanations of human behavior that ignore the complex, highly coordinated system of regulatory dynamics involved in development and evolution.The prestige of success enjoyed by the gene theory might become a hindrance to the understanding of development by directing our attention solely to the genome. . . . Already we have theories that refer the processes of development to genic action and regard the whole performance as no more than the realization of the potencies of the genes. Such theories are altogether too one-sided. (Harrison, 1937, p. 370) There is growing consensus in popular culture that by understanding genes and the mutual interactions of the proteins derived from them it is possible to understand all of life, including human nature. Psychology is no stranger to this perspective. As most psychologists are aware, a blend of ethology and sociobiology known as evolutionary psychology has gained increasing attention and recognition over the past several decades. Arguments for the heuristic value of a gene-centered, evolutionary approach to the study of human behavior have become increasingly evident in mainstream psychology journals (i.e., Buss & Schmitt, 1993;Buss & Shackelford, 1997;Cosmides & Tooby, 1994a;Ellis, 1998;Tooby & Cosmides, 1990a), and popular texts promoting this perspective have likewise flourished in recent years (i.e., Allman, 1994;Buss, 2000;Dennett, 1995;Gazzaniga, 1992;Pinker, 1994Pinker, , 1997Pinker, , 2002R. Wright, 1994). Fueled in large part by the influence of sociobiology on the behavioral sciences over the past several decades, proponents of evolutionary psychology assert that applying insights from evolutionary theory to explanations of human behavior will stimulate more fruitful research programs and provide a powerful framework for discovering evolved psychological mechanisms thought to be forged by natural selection operating over thousands of generations (Bjorklund & Pellegrini, 2000Buss, 1989Buss, , 1991Charlesworth, 1986;Tooby & Cosmides, 1990b).Ideas gleaned from evolutionary biology have certainly influenced theory building in psychology (see Cairns, 1998;Cairns, Gariepy, & Hood, 1990;Edelman, 1989;Gottlieb, 1991Johnston, 1985;Sameroff, 1983). There is little doubt that the incorporation of evolutionary principles and perspectives into the psychological sc...

That the senses provide overlapping information for objects and events is no extravagance of nature. This overlap facilitates attention to critical aspects of sensory stimulation, those that are redundantly specified, and attenuates attention to nonredundantly specified stimulus properties. This selective attention is most pronounced in infancy and gives initial advantage to the perceptual processing of, learning of, and memory for stimulus properties that are redundant, or amodal (e.g., synchrony, rhythm, and intensity), at the expense of modality-specific properties (e.g., color, pitch, and timbre) that can be perceived through only one sense. We review evidence supporting this hypothesis and discuss its implications for theories of perceptual, cognitive, and social development.

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In the simplest of terms, attention refers to a selectivity of response. Man or animal is continuously responding to some events in the environment and not to others that could be responded to (or noticed) just as well.

L. Bahrick and R. Lickliter (2000) proposed an intersensory redundancy hypothesis that states that information presented redundantly and in temporal synchrony across two or more sensory modalities selectively recruits infant attention and facilitates perceptual learning more effectively than does the same information presented unimodally. In support of this view, they found that 5-month-old infants were able to differentiate between two complex rhythms when they were presented bimodally, but not unimodally. The present study extended our test of the intersensory redundancy hypothesis to younger infants and to a different amodal property. Three-month-olds' sensitivity to the amodal property of tempo was investigated. Results replicated and extended those of Bahrick and Lickliter, demonstrating that infants could discriminate a change in tempo following bimodal, but not unimodal, habituation. It appears that when infants are first learning to differentiate an amodal stimulus property, discrimination is facilitated by intersensory redundancy and attenuated under conditions of unimodal stimulation.

This study examined the ability of bobwhite quail embryos and hatchlings to learn an individual bobwhite maternal call. Results revealed that embryos could learn an individual maternal call and remember that call for at least 24 hr following exposure. In contrast, hatchlings reared socially in groups of same-age chicks during postnatal exposure to a maternal call did not demonstrate a preference for that familiar call at 24 hr following exposure. However, individual auditory recognition was exhibited by hatchlings reared in social isolation, suggesting that the perceptual and social complexity of the postnatal situation can disrupt or interfere with early auditory learning. Additional support for this view was the finding that embryos exposed to unusually early visual stimulation during prenatal exposure to a maternal call also failed to prefer that familiar maternal call in subsequent choice tests. The idea that early auditory learning capacity is determined more by context and experience rather than the organism's specific age or stage of development is discussed.

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