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12 - Physiological and Evolutionary Precursors
- from Part I - Psychology’s Historical Foundations
- James F. Brennan, Catholic University of America, Washington DC, Keith A. Houde, Ave Maria University, Florida
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- Book:
- History and Systems of Psychology
- Published online:
- 04 November 2022
- Print publication:
- 17 November 2022, pp 218-240
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Summary
As psychology emerged as a discipline in the nineteenth century, advances were made in the understanding of the nervous system. The specific functions of nerve fibers were described by Bell and Magendie. Müller’s analysis of neural conduction led Du Bois-Reymond and Helmholtz to describe the nerve impulse. As a reaction against Gall’s phrenology, localization of brain functions reached systematic description by Flourens and Sherrington. Concurrently, advances in physics led to experimental studies of sensations by Young, Helmholtz, and Müller, while Purkinje justified subjective sensory experience. The second intellectual backdrop to psychology was psychophysics, which proposed that sensory experience is not completely reducible to physics and physiology. Although Weber contributed both methodologically and substantively to psychophysics, its clearest expression is found in the quantitative analysis of Fechner. His work received strong support from the experiments of Helmholtz, especially in his doctrine of unconscious inference in perception. The final movement was centered on Darwin’s theory of evolution by natural selection, which completed the Copernican revolution in science and established the primacy of scientific empiricism. Spencer applied Darwin’s writings to evolutionary associationism, and Galton made an intensive examination of individual differences through mental testing. All three movements demonstrated the efficacy of empirical science.
Chapter 23 - Fechner
- from Part IV - Mind, Body, Spirit
- Edited by Charles Youmans, Pennsylvania State University
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- Book:
- Mahler in Context
- Published online:
- 18 December 2020
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- 19 November 2020, pp 198-206
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The physicist, psychophysicist, physician, and philosopher Gustav Theodor Fechner – an intellectual force occupying Mahler from his student years in Vienna through the composition of Das Lied von der Erde – is often described as a “mystic” or a “speculative thinker” whose fantastical philosophical system attempts to reconcile mechanistic science with an “animistic non-rational world-view.” Accordingly, his theories are usually dismissed today as curiosities. But though Fechner’s views may appear strange, on closer examination they are not mere arbitrary convictions; rather, they have a rational foundation. Furthermore, it can be demonstrated that Fechner, unorthodox thoughts notwithstanding, made important contributions to the natural sciences: particularly in the notions of “psychophysical parallelism” of the “day view,” a response to contemporaneous materialist and mechanistic orientations. The basic details of these Fechnerian ideas are presented here, along with an account of his early reception.
4 - Sensation and Perception
- Edited by Robert J. Sternberg, Cornell University, New York, Wade E. Pickren, Ithaca College, New York
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- Book:
- The Cambridge Handbook of the Intellectual History of Psychology
- Published online:
- 18 May 2019
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- 16 May 2019, pp 88-110
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Sensory science began with the Greek philosophers (back to 600 BC). One early view: sensory experience is a faithful reflection of the physical world. As history swept through the Roman Empire, the fall of Rome and the transfer of science to Arabic scholars, sensory science as we know it had to await Andreas Vesalius and human dissections in the sixteenth century. Luigi Galvani’s animal electricity (eighteenth century) ushered in the scientific explosion of the nineteenth century that brought us Johannes Müller (doctrine of specific nerve energies) and the birth of psychology in the laboratory of Wilhelm Wundt (1879). Advances rapidly showed how information from each of our senses is processed through the nervous system; contrary to the Greeks, our perceptions are not always a faithful reflection of the physical world. Just as with physical science, sensory science requires measurement. Gustav Fechner argued that the unit of sensation is the jnd (the just-noticeable difference a stimulus must be increased for a person to detect a difference). This view held for a century until S. S. Stevens noted all jnds did not appear to be equal. He revolutionized the study of sensory and perceptual experience, and that revolution continues today.
2 - Methodology in Psychology
- Edited by Robert J. Sternberg, Cornell University, New York, Wade E. Pickren, Ithaca College, New York
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- Book:
- The Cambridge Handbook of the Intellectual History of Psychology
- Published online:
- 18 May 2019
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- 16 May 2019, pp 29-62
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Psychology, perhaps more than any other social science, has historically defined itself by the methodologies it employs in generating new knowledge. This chapter surveys the history of methodology in psychology. We begin by first defining the concept of a methodology, then survey early scientific methods of psychology with the work of Gustav Fechner in the 1860s. Fechner, along with other psychophycisists of the time, were of the first to promote a rigorous scientific method in the study and understanding of psychological phenomena. The quest for quantification in psychology would continue with the work of Francis Galton and his monumental discovery of empirical correlation almost thirty years later, which set the stage for a wealth of statistical methodologies that would arise in the early twentieth century. These included the birth of psychometrics and testing, as well as the development of the factor analysis method used by Charles Spearman and others. By the early 1920s, geneticist R. A. Fisher revolutioned the application of quantitative methods by promoting null hypothesis significance testing, while simultaneously packaging experimental design into the method of the analysis of variance. We close the chapter with a survey of Sewall Wright’s method of path analysis, which, along with factor analysis (and the advancement of the computer), set the stage for the birth of structural equation models of the mid-to-late twentieth century. While psychological science has been dominated by quantitative methods, the reemergence of qualitative methods is also noteworthy. We conclude with a comment that psychological methods of the future, to be successful, will likely require a merger of both quantitative and qualitative approaches.
Psychophysical scaling: Judgments of attributes or objects?
- Gregory R. Lockhead
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- Journal:
- Behavioral and Brain Sciences / Volume 15 / Issue 3 / September 1992
- Published online by Cambridge University Press:
- 19 May 2011, pp. 543-558
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Psychophysical scaling models of the form R = f(I), with R the response and I some intensity of an attribute, all assume that people judge the amounts of an attribute. With simple biases excepted, most also assume that judgments are independent of space, time, and features of the situation other than the one being judged. Many data support these ideas: Magnitude estimations of brightness (R) increase with luminance (I). Nevertheless, I argue that the general model is wrong. The stabilized retinal image literature shows that nothing is seen if light does not change over time. The classification literature shows that dimensions often combine to produce emergent properties that cannot be described by the elements in the stimulus. These and other effects cannot be adjusted for by simply adding variables to the general model because some factors do not combine linearly. The proposed alternative is that people initially judge the entire stimulus – the object in terms of its environment. This agrees with the constancy literature that shows that objects and their attributes are identified through their relations to other aspects of the scene. That the environment determines judgments is masked in scaling studies where the standard procedure is to hold context constant. In a typical brightness study (where different lights are presented on the same background on different trials) the essential stimulus might be the intensity of the light or a difference between the light and the background. The two are perfectly confounded. This issue is examined in the case of audition. Judgments of the loudness of a tone depend on how much that tone differs from the previous tone in both pitch and loudness. To judge loudness (and other attributes) people first seem to process the stimulus object in terms of differences between it and other aspects in the situation; only then do they assess the feature of interest. Psychophysical judgments will therefore be better interpreted by theories of attention that are based in biology or psychology than those (following Fechner) that are based in classical physics.
A perspective for viewing the history of psychophysics
- David J. Murray
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- Journal:
- Behavioral and Brain Sciences / Volume 16 / Issue 1 / March 1993
- Published online by Cambridge University Press:
- 04 February 2010, pp. 115-137
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Fechner's conception of psychophysics included both “outer psychophysics” the relation between stimulus intensity and the response reflecting sensation strength, and “inner psychophysics” the relation between neurelectric responses and sensation strength. In his own time outer psychophysics focussed on the form of the psychophysical law, with Fechner espousing a logarithmic law, Delboeuf a variant of the logarithmic law incorporating a resting level of neural activity, and Plateau a power law. One of the issues on which the dispute was focussed concerned the appearance of contrasts if the overall illumination was increased or decreased; another issue was the question of whether a sensation of a “just noticeable difference” established for one value of a sensory dimension appeared the same for a value elsewhere on the dimension. The development of “inner psychophysics” led through the works of Delboeuf, Solomons, Jastrow, and Thurstone to modern signal detection theory. A third line of research, devoted to the question of what was meant by the “measurement” of sensation strength, stemmed from the criticism of Fechner's work by von Kries (1882) and others. Although a valid body of science could be built up without the intervening variable called “sensation strength,” such a science might be a cumbersome representation of reality. When an optical contrast is set up, and its overall illumination is increased or decreased, subjective contrasts involving medium levels of lightness vary little as illumination varies (as a power law based on sensation ratios or a logarithmic law based on sensation differences predict), but subjective contrasts involving extreme levels of lightness might be subject to the effects of other variables.
Reconciling Fechner and Stevens: Toward a unified psychophysical law
- Lester E. Krueger
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- Journal:
- Behavioral and Brain Sciences / Volume 12 / Issue 2 / June 1989
- Published online by Cambridge University Press:
- 04 February 2010, pp. 251-267
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How does subjective magnitude, S. increase as physical magnitude or intensity, I, increases? Direct ratings (magnitude scales; partition or category scales) can be fitted by the power function, S = aIb, in which S equals I raised to a power or exponent, b, and multiplied by a measure constant, a. The exponent is typically about twice as large for the magnitude scale (Stevens) as for the corresponding partition or category scale, but the higher exponent may be explained by the overly expansive way people use numbers in making magnitude estimations. The partition or category scale and the adjusted (for the use of number) magnitude scale for a given modality or condition generally agree with the neurelectric scale and the summated just noticeable difference (jnd) scale. A unified psychophysical law is proposed in which each jnd has the same subjective magnitude for a given modality or condition, subjective magnitude increases as approximately a power function of physical magnitude with the exponent ranging from near 0 to 1 (compressive function), and subjective magnitude depends primarily on peripheral sensory processes, that is, no nonlinear central transformations occur. An undue reliance on Weber's law blinded Fechner to the fact that the true psychophysical scale is approximately a power function. Rejecting Weber's law, which is not valid, means that we no longer have to choose between letting the summated jnd scale be a logarithmic function (Fechner's law) and introducing a nonlinear central transformation to make it into a power function (Brentano–Ekman-Teghtsoonian's law). Fechner and Stevens erred equally about the true psychophysical power function, whose exponent lies halfway between that of Fechner (an exponent approaching zero) and that of Stevens. To be reconciled, Fechnerians must give up the assumptions that Webers law is valid and that the jnd has the same subjective magnitude across modalities and conditions; Stevensians must give up the assumption that the unadjusted (for the use of number) magnitude scale is a direct measure of subjective magnitude.