Steroidanthropometric Theory See Sexual Orientation Theories

STEVENS' POWER LAW. = Stevens' law = Stevens' power function = power law. The American psychologist/psychophysicist Stanley Smith Stevens (1906-1973) proposed this generalization, which states that the psy-chophysical relationship between a physical stimulus and the psychological experience or perceived magnitude of that stimulus is given by the equation: P = k Sn, where perceived magnitude (P) equals a constant (k) times the stimulus intensity (S) raised to a power, n. On the basis of the stability of his data, Stevens proposed that the psychophysical law is best represented as a power relation rather than a logarithmic relation as described by Fechner's law. S. S. Stevens and E. Galanter distinguish between two kinds of perceptual continua, prothetic and metathetic. Prothetic continua are concerned with "how much" and represent dimensions on which discriminations involve an additive process on the physiological level (e.g., loudness, brightness, heaviness, and duration), and metathetic continua are concerned with "what kind" or "where" and represent dimensions on which discriminations involve a substitutive process at the physiological level (e.g., pitch and apparent inclina tion). Stevens points out that although Fechner's assumption (Fechner's law) of the equality of "just noticeable differences" (JNDs) may hold for metathetic dimensions, it definitely does not hold for prothetic dimensions. Using the "magnitude methods" (magnitude estimation; magnitude production), Stevens found that psychophysical magnitude does not increase as a logarithmic function of stimulus magnitude, as Fechner had maintained but, rather, as a power function in accord with the Belgian physicist Joseph Plateau's (1801-1883) earlier prediction in 1872. That is, perceived magnitude is proportional to physical magnitude raised to some power (Stevens' power law). The consistency of Stevens' power function obtained in magnitude estimation experiments led some researchers to assert that it is one of the most firmly established quantitative statements in psychology (cf., R. Warren's physical correlate theory). The magnitude-judgment techniques of Stevens led to the development of what has been called the "new psychophysics" in which perceived magnitude is measured directly rather than indirectly as in the classical approach developed by Gustav Fechner. Because a number of challenges may be made to Stevens' power law, it may be premature to speak of the psychophysical law; the newer investigations hold the promise of generating a broader approach to psychophysical measurement and, perhaps, of generating more general psychological laws, of which the psy-chophysical law may represent only a special case. See also FECHNER'S LAW; OPERA-TIONISM, DOCTRINE OF; WEBER'S LAW.

Conquering Fear In The 21th Century

Conquering Fear In The 21th Century

The Ultimate Guide To Overcoming Fear And Getting Breakthroughs. Fear is without doubt among the strongest and most influential emotional responses we have, and it may act as both a protective and destructive force depending upon the situation.

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