Like many other words in psychology, adaptation has multiple meanings. At the basis of all the meanings, however, is the concept carried by its Latin root, adaptare: to fit.
Among ethologists, who think that characteristic species-typical behaviors are distillations of evolutionary processes, each physical and behavioral characteristic of a species is the product of and contributes to its adaptive radiation, the multiplication of individuals that can survive in the changing environment, and the diversification of the species in a diverse environment. Such adaptation is genetically based and requires numerous generations to be accomplished.
In contrast to this genetic adaptation are phenotypic adaptations, often only seconds in duration, which occur within the life span of an individual. The results of these adaptations are not transmitted to the offspring, although the capacity for such adaptation is. Implicit in the concept is the alteration of an individual by the presence of a persistent, nontoxic or nontraumatic, nonfatiguing stimulus, or by the prolonged cessation and absence of a customary, persistent stimulus, such as weightlessness. Examples of such adaptation include the gradual diminution in the coldness of water after we immerse our hand in it; the reduction in loudness of a tone after a few seconds; and the return of sight (though colorless) after a period in a darkened room following exposure to bright lights, and the return of comfortable color vision after reexposure to a brightly lighted environment. The mechanisms involved in these examples are all different: stimulus (receptor) failure in the cold; activation of an acoustic reflex (plus receptor change); and bleaching and regeneration of photopigments plus neural change in the retina. In general, scientists tend to think of this kind of adaptation as occurring in or affecting the receptor, whereas the term for a similar phe-nomenon—habituation—is reserved for those situations in which more central events are at least involved if not prominent.
A so-called "General Adaptation Syndrome" was pro posed by Selye (1950) as part of our typical response to dangerous environmental challenge. This syndrome is an extension of Cannon's Emergency Syndrome (1932/1960) the "flee, fright, or fight" syndrome, consisting of a rapid total body response to the challenge. Many manifestations of the adaptation syndrome have been observed in lower animals, but they often are difficult to detect in humans. Other concepts (e.g., acclimatization) have been proposed to account for many of the data.
Cannon, W. B. (1960). The wisdom of the body. New York: Norton.
(Original work published 1932) Selye, H. (1950). Stress. Montreal, Canada: Acta.
Arthur J. Riopelle See also: Accommodation; General Adaptation Syndrome
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