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The study of mental processes by physical methods.
The study of the relations of stimuli to the sensations they produce.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a psychological discipline that studies the quantitative relations between the physical characteristics of a stimulus and the intensity of the sensation evoked by the stimulus.

Psychophysics deals with two main groups of problems: measurement of the stimulus threshold, that is, the sensitivity limit of the human sensory system, and the construction of psychophysical scales. The first group of problems arose as a result of measurements of the intensity of sensation made in the 19th century by the German scientists W. E. Weber and G. Fechner; these measurements involved indirect scaling, in which the intensity of sensation is a mathematical function of the magnitude of the stimulus. The threshold was regarded as the point in a series of stimuli of increasing intensity that divides the series into two parts, one that causes sensation and one that does not. Modern psychophysics—or rather its applied branch, the theory of detecting signals against a background of noise—regards the threshold as a “threshold zone,” within which the probability of a response varies between 0 and 1. Dynamic sensitivity theories deny that a sensory threshold exists as an independent reality.

The second group of problems arose in connection with the use by the American scientist S. Stevens of direct scaling. In direct scaling, the magnitude of sensation—a point on the sensory scale—is determined by the subject’s own indication of the distance or relation between the intensities of stimuli in arbitrary units. Research on both groups of problems is concerned with the main theoretical problem of psychophysics, namely, the structure and metrics of the psychophysical stimulus space of sensations, which is understood as a multivector, noneuclidean space.


Kravkov, S. V. Ocherk obshchei psikhofiziologii organov chuvstv. Moscow-Leningrad, 1946.
Eksperimental’naia psikhologiia, fascs. 1–2. Edited by P. Fraisse and J. Piaget. Moscow, 1966. (Translated from French.)
Problemy psikhofiziki: Sb. Moscow, 1974.
Fechner, G. T. Elemente der Psychophysik, 3rd ed., vols. 1–2. Leipzig, 1907.
Guilford, J. P. Psychometric Methods, 2nd ed. New York, 1954.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
our ultimate goal is to provide practicing psychophysicists with instructions as to how to configure the psychophysical method that renders the best sampling plan for the estimation of [PSI].
What psychophysicists have discovered about human color vision, is that there is more variability than we might suppose.
Sounds are perceived in terms of pitch, loudness, timbre, and other features typically analyzed by psychologists and psychophysicists (e.g., Rasch & Plomp, 1999).
Physiological psychologists and psychophysicists dominate research in the first two areas.
A more complete discussion of power patterns in early psychophysical studies of visual phenomena can be found in Stevens (1975) and Warren (1981), whose historical sketches show that the possibility of using power functions to describe psychophysical response can be traced back to the psychophysicists of the late 19th century.
Gibson's problem was that he underestimated the difficulty of detecting these "physical invariants" (which, Marr argues, does require computation, contra Gibson), and so Gibson saw his ideas as being in competition with those of psychophysicists and other computationally-minded psychologists working in perception.
Instead, we can now ask whether a particular kind of attentional manipulation affects a particular type of perceptual judgment (as many psychophysicists are starting to do; e.g.
("Intensity" has a specific acoustic meaning that may result in the statement being incorrect in some circumstances.) Some psychophysicists might object to occasional oversimplifications, but it is always difficult to end up on the right side of the boundary between simplification and oversimplification when writing books at an introductory level.

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