Historical accounts of the development of scientific psychology place the origins of the discipline in Germany at about the middle of the nineteenth century. The ferment produced by British and continental philosophies of mind and the advances of research in sensory physiology provided the immediate context for the beginning of the new psychology. The pursuit of knowledge about mind and its processes has a history that is embedded in the history of philosophy. The late-eighteenth-century declaration that a true scientific study of the mind was not possible posed a challenge that was answered in the nineteenth century when the possibility of a scientific study of mind emerged within philosophy by the adoption of the experimental methods employed to study the physiology of the senses. The synergy of these nineteenthcentury developments gave impetus to the “new psychology” whose history embodies continued efforts to develop and
maintain psychology as a scientific discipline and to extend the methods of science to an ever-widening field of inquiry within the discipline.
Thursday, July 17, 2008
The Philosophical Context
Christian Wolff (1679–1754) first popularized the term psychology to designate the study of mind. Wolff divided the discipline between empirical and rational psychology. The data of mind that resulted from observing ourselves and others constituted empirical psychology; rational psychology referred to the interpretation of the data of empirical psychology through the use of reason and logic. These psychologies were characterized as using knowledge acquired through experience (empirical psychology) or using knowledge that the mind possesses independent of experience (rational psychology) (Murray, 1988). Immanuel Kant (1724–1804) denied the validity of any rational psychology because, he argued, rational mental processes must be activated by mental content derived from experience; therefore, the study of mind must be confined to questions appropriate to an empirical psychology (Leary,
1978). An empirical psychology of mental content could not, Kant contended, become a proper natural science because mental events cannot be quantified (i.e., measured or weighed), and thus its data are neither capable of being described mathematically
nor subject to experimental manipulation. Finally, Kant asserted, the method of observing the mind—introspection—distorts the events observed by observing them. However, Kant suggested, psychology might improve its status as an empirical science by adopting the methods of anthropology to observe the activities of human beings in realistic settings. This study (Leary, 1978), supplemented by drawing upon literature, history, and biography as sources of information about the manifestation of mind in human activity, would base psychology upon objective observations of public events and avoid the limitations of an empirical psychology based solely on internal observation of private events. Responses to Kant were not long in coming. Jakob Friederich Fries (1773–1843) raised the status of introspection by arguing that it was not inherently more problematic than observing external phenomena; if introspection was unreliable, at least it was not any more so than any other kind of observation. At the same time, Johann Friederich Herbart (1776–1841) offered a system of psychology that was both empirical and mathematical. If psychology needed to be mathematical to be a true science, Herbart proposed that numbers could be assigned to mental events of different intensities and a mathematical description of the relationship among them could be formulated. Herbart could assign numbers to
describe experiences of different intensities, but he could not actually measure the subjective intensities in accord with an objective standard. Eduard Friederich Beneke (1798–1854) argued that it was premature to apply mathematics to relationships
among mental events absent more accurate empirical observations and reliable means of measurement; psychology could hope to become an experimental discipline by testing
“empirical results and theoretical hypotheses under controlled conditions and with the systematic variation of variables” (Leary, 1978, p. 119). Kant’s suggestion that psychology should utilize observations of human beings in their social environment, the rescue by Fries of introspection as a method for observing internal events, Herbart’s suggestion that psychological phenomena could, in principle, be described mathematically, and Beneke’s suggestion that psychological experiments were possible
contributed to the inception of scientific psychology. By suggesting that a science of psychology was not possible, Kant stimulated both counterarguments and the search for the means to make psychology a scientific discipline of equal rank with
the natural sciences. It remained for others to attempt to establish introspection as a scientific method, to devise the conditions and methods of an experiment in psychology, and to quantify psychological phenomena and formulate theoretical
and mathematical descriptions of the relationships among them.
1978). An empirical psychology of mental content could not, Kant contended, become a proper natural science because mental events cannot be quantified (i.e., measured or weighed), and thus its data are neither capable of being described mathematically
nor subject to experimental manipulation. Finally, Kant asserted, the method of observing the mind—introspection—distorts the events observed by observing them. However, Kant suggested, psychology might improve its status as an empirical science by adopting the methods of anthropology to observe the activities of human beings in realistic settings. This study (Leary, 1978), supplemented by drawing upon literature, history, and biography as sources of information about the manifestation of mind in human activity, would base psychology upon objective observations of public events and avoid the limitations of an empirical psychology based solely on internal observation of private events. Responses to Kant were not long in coming. Jakob Friederich Fries (1773–1843) raised the status of introspection by arguing that it was not inherently more problematic than observing external phenomena; if introspection was unreliable, at least it was not any more so than any other kind of observation. At the same time, Johann Friederich Herbart (1776–1841) offered a system of psychology that was both empirical and mathematical. If psychology needed to be mathematical to be a true science, Herbart proposed that numbers could be assigned to mental events of different intensities and a mathematical description of the relationship among them could be formulated. Herbart could assign numbers to
describe experiences of different intensities, but he could not actually measure the subjective intensities in accord with an objective standard. Eduard Friederich Beneke (1798–1854) argued that it was premature to apply mathematics to relationships
among mental events absent more accurate empirical observations and reliable means of measurement; psychology could hope to become an experimental discipline by testing
“empirical results and theoretical hypotheses under controlled conditions and with the systematic variation of variables” (Leary, 1978, p. 119). Kant’s suggestion that psychology should utilize observations of human beings in their social environment, the rescue by Fries of introspection as a method for observing internal events, Herbart’s suggestion that psychological phenomena could, in principle, be described mathematically, and Beneke’s suggestion that psychological experiments were possible
contributed to the inception of scientific psychology. By suggesting that a science of psychology was not possible, Kant stimulated both counterarguments and the search for the means to make psychology a scientific discipline of equal rank with
the natural sciences. It remained for others to attempt to establish introspection as a scientific method, to devise the conditions and methods of an experiment in psychology, and to quantify psychological phenomena and formulate theoretical
and mathematical descriptions of the relationships among them.
The Scientific Context
The emerging natural sciences of the eighteenth and nineteenth centuries became increasingly specialized as knowledge increased and as opportunities for specialized teaching and research came into being in the German universities (Ben-David, 1971). The study of physiology emerged as a discipline separate from anatomy as the nineteenth century began. Studying intact physiological systems, in vivo or in vitro, accelerated the understanding of the functional characteristics of those systems and built on the knowledge gained from the study of anatomy via dissection. The methods and subject matter of physiology, especially sensory physiology, helped to provide the scientific basis for psychology.
Sensory Physiology
Johannes Müller (1801–1858), the “Father of Physiology,” produced the classic systematic handbook (Handbuch der Physiologie des Menschen, 1833–1840) that set forth what was then known about human physiology and offered observations and hypotheses for further research. Among the formulations that Müller provided in the Handbuch was the law of specific nerve energies, which stated that the mind is not directly aware of objects as such but can only be aware of the stimulation in the brain conveyed by sensory nerves. The perceived qualities of stimulation depend upon the sense
organ stimulated, the nerve that carries the excitation from the sense organ, and the part of the brain that receives the stimulation. Müller’s pupil, Hermann von Helmholtz (1821–1894), extended the law of specific nerve energies by theorizing that
qualities of stimuli within a sensory modality are encoded in the same way that they are encoded among modalities. That is, distinguishing red from green, or a low pitch from a high one, depended upon specialized receptors in the eye or ear, distinct nerve connections within the visual or auditory system, and specific locations within the visual or auditory areas of the brain that receive the stimulation. The testing of the theory depended upon an individual’s report of the sensory experience (“I see red”), the nature of the stimulus to which the individual responded (a specific wavelength of the energy spectrum), and knowledge of the physiological organization
of the sensory systems. Relating the experience to the stimulus was a matter of experimental research that could be carried out with intact human beings; detecting the activity of nerves and the location of the brain to which stimulation was
transmitted was possible then only with in vitro preparations of animals. Relating subjective, psychological experience to specific external stimulation was one step in suggesting how psychology might become a science.
organ stimulated, the nerve that carries the excitation from the sense organ, and the part of the brain that receives the stimulation. Müller’s pupil, Hermann von Helmholtz (1821–1894), extended the law of specific nerve energies by theorizing that
qualities of stimuli within a sensory modality are encoded in the same way that they are encoded among modalities. That is, distinguishing red from green, or a low pitch from a high one, depended upon specialized receptors in the eye or ear, distinct nerve connections within the visual or auditory system, and specific locations within the visual or auditory areas of the brain that receive the stimulation. The testing of the theory depended upon an individual’s report of the sensory experience (“I see red”), the nature of the stimulus to which the individual responded (a specific wavelength of the energy spectrum), and knowledge of the physiological organization
of the sensory systems. Relating the experience to the stimulus was a matter of experimental research that could be carried out with intact human beings; detecting the activity of nerves and the location of the brain to which stimulation was
transmitted was possible then only with in vitro preparations of animals. Relating subjective, psychological experience to specific external stimulation was one step in suggesting how psychology might become a science.
Psychophysics
Experiments on the sense of touch were carried out by the physiologist E. H. Weber (1795–1878), who distinguished among the feelings of pressure, temperature, and the location of stimulation on the skin. In conducting experiments in which he stimulated his own skin, Weber explored skin sensitivity and demonstrated that “on the tip of the forefinger and lips two fine compass points could be felt as two when they were less than one-twentieth of an inch apart, but if they were nearer they seemed to be one” (Hall, 1901, p. 727). Not only could touch sensitivity be measured at different points on the skin, but relative sensitivity at a single point could also be measured. Placing a standard weight at a given spot on the skin and then asking for a second weight to be judged “heavier” or “lighter” showed that the amount of weight that could be judged heavier or lighter than the standard varied as a proportion of the magnitude of the standard weight. Thus, the minimal detectable difference between two weights was relative to the weights involved; for heavy weights, differences
would have to be large, but smaller differences could be detected when the weights involved were light. G. T. Fechner (1801–1887), a physicist, saw in Weber’s
results the possibility of relating mental events to physical events; subjective judgments about physical magnitudes could be compared to the actual physical magnitudes. Fechner had believed since his student days “that the
phenomena of mind and body run in parallel” (Marshall, 1982, p. 67). His solution to the problem of relating these two aspects of the world was to make “the relative increase of bodily energy the measure of the increase of the corresponding
mental intensity” (Adler, 1966, p. xii). Although Fechner conceived of the possibility independently of Weber’s results, he came to realize that his speculations about arithmetic and logarithmic relations between physical and
subjective magnitudes were in fact demonstrated by Weber’s observations (Adler, 1966; Marshall, 1982).
Weber’s results showed that sensory judgments of magnitude formed ratios that were sufficiently regular to assume the status of a law. Fechner designated as Weber’s law the mathematical equation that stated that the increase in perceived intensity
of a stimulus (the “just noticeable difference”) was, as Weber had demonstrated, a constant proportion of the intensity of the stimulus to be increased. The regularity in ratios across a wide range of intensities led Fechner to rewrite the law in terms of a logarithmic progression, with the strength ofa sensation equal to the logarithm of the intensity of a stimulus multiplied by a constant established experimentally for the sensory system under study (Murray, 1988, pp. 176–185). “Weber’s law” now typically refers to the “simple statementthat the just noticeable difference in a stimulus bears a constant ratio to the stimulus” (Adler, 1966, p. xiv), while “Fechner’s law” typically refers to the logarithmic relationship that Fechner formulated.
Fechner called the new science that he established psychophysics and developed laboratory procedures that became part of the laboratory experiments of the new psychology as well as of the physiological research on the special senses. The measurements of the smallest detectable intensity (absolute threshold) and the smallest detectable difference in intensities between stimuli (difference threshold) for the different senses were pursued by the several methods that Fechner had devised for the purpose (see, e.g., Woodworth,1938). Resolving differences in results obtained for different methods, testing psychophysical laws over a wide range of
stimulus intensities, and developing scales of psychological measurement offered significant research challenges for psychological laboratories well into the twentieth century (Stevens, 1951; Woodworth, 1938).
would have to be large, but smaller differences could be detected when the weights involved were light. G. T. Fechner (1801–1887), a physicist, saw in Weber’s
results the possibility of relating mental events to physical events; subjective judgments about physical magnitudes could be compared to the actual physical magnitudes. Fechner had believed since his student days “that the
phenomena of mind and body run in parallel” (Marshall, 1982, p. 67). His solution to the problem of relating these two aspects of the world was to make “the relative increase of bodily energy the measure of the increase of the corresponding
mental intensity” (Adler, 1966, p. xii). Although Fechner conceived of the possibility independently of Weber’s results, he came to realize that his speculations about arithmetic and logarithmic relations between physical and
subjective magnitudes were in fact demonstrated by Weber’s observations (Adler, 1966; Marshall, 1982).
Weber’s results showed that sensory judgments of magnitude formed ratios that were sufficiently regular to assume the status of a law. Fechner designated as Weber’s law the mathematical equation that stated that the increase in perceived intensity
of a stimulus (the “just noticeable difference”) was, as Weber had demonstrated, a constant proportion of the intensity of the stimulus to be increased. The regularity in ratios across a wide range of intensities led Fechner to rewrite the law in terms of a logarithmic progression, with the strength ofa sensation equal to the logarithm of the intensity of a stimulus multiplied by a constant established experimentally for the sensory system under study (Murray, 1988, pp. 176–185). “Weber’s law” now typically refers to the “simple statementthat the just noticeable difference in a stimulus bears a constant ratio to the stimulus” (Adler, 1966, p. xiv), while “Fechner’s law” typically refers to the logarithmic relationship that Fechner formulated.
Fechner called the new science that he established psychophysics and developed laboratory procedures that became part of the laboratory experiments of the new psychology as well as of the physiological research on the special senses. The measurements of the smallest detectable intensity (absolute threshold) and the smallest detectable difference in intensities between stimuli (difference threshold) for the different senses were pursued by the several methods that Fechner had devised for the purpose (see, e.g., Woodworth,1938). Resolving differences in results obtained for different methods, testing psychophysical laws over a wide range of
stimulus intensities, and developing scales of psychological measurement offered significant research challenges for psychological laboratories well into the twentieth century (Stevens, 1951; Woodworth, 1938).
Mental Chronometry
Johannes Müller had speculated in his Handbuch that the
speed of transmission of a nerve impulse was greater than the
speed of light. Helmholtz tested that hypothesis by measuring
the time to react (“reaction time”) to stimuli applied to motor
nerves of different lengths in a frog and found the time to be
much slower than the speed of light (Boring, 1950; Hall,
1901). He extended this research to sensory nerves by measuring
the time to respond by a human to a touch on the toe and a
touch on the thigh and demonstrated that he time to respond
was slower for the impulse that had longer to travel. Helmholtz
extended the use of time to measure a sensory-motor response
to include spoken responses to words, providing a measure of
the time necessary to associate words or ideas.
The determination of reaction times to measure the speed of
mental processes was investigated by the Dutch physiologist
F. C. Donders (1818–1889). Donders began with the time to
make a motor response to a stimulus (simple reaction time)
and then added more stimuli, each with a different response.
By subtracting simple reaction time from the time taken to
make the correct response to one of several stimuli, Donders
believed that he had measured the time required to make a
choice (Boring, 1950;Woodworth, 1938). He then recognized
that his experimental procedure required not only that an observer
choose a response from among the several responses
possible but also that an observer detect which stimulus had
been presented from among the several possible stimuli (discrimination
reaction time). Using the subtractive method that
he devised, Donders estimated the time for a simple reaction,
the time taken to discriminate one stimulus from others, and
the time taken to choose a response. The possibility of measuring
the time required by mental processes appeared to have
been realized, and the reaction-time experiment as well as the
subtractive procedure became part of the science of psychology
(for modern adaptations, see Posner & Raichle, 1994;
Sternberg, 1969).
speed of transmission of a nerve impulse was greater than the
speed of light. Helmholtz tested that hypothesis by measuring
the time to react (“reaction time”) to stimuli applied to motor
nerves of different lengths in a frog and found the time to be
much slower than the speed of light (Boring, 1950; Hall,
1901). He extended this research to sensory nerves by measuring
the time to respond by a human to a touch on the toe and a
touch on the thigh and demonstrated that he time to respond
was slower for the impulse that had longer to travel. Helmholtz
extended the use of time to measure a sensory-motor response
to include spoken responses to words, providing a measure of
the time necessary to associate words or ideas.
The determination of reaction times to measure the speed of
mental processes was investigated by the Dutch physiologist
F. C. Donders (1818–1889). Donders began with the time to
make a motor response to a stimulus (simple reaction time)
and then added more stimuli, each with a different response.
By subtracting simple reaction time from the time taken to
make the correct response to one of several stimuli, Donders
believed that he had measured the time required to make a
choice (Boring, 1950;Woodworth, 1938). He then recognized
that his experimental procedure required not only that an observer
choose a response from among the several responses
possible but also that an observer detect which stimulus had
been presented from among the several possible stimuli (discrimination
reaction time). Using the subtractive method that
he devised, Donders estimated the time for a simple reaction,
the time taken to discriminate one stimulus from others, and
the time taken to choose a response. The possibility of measuring
the time required by mental processes appeared to have
been realized, and the reaction-time experiment as well as the
subtractive procedure became part of the science of psychology
(for modern adaptations, see Posner & Raichle, 1994;
Sternberg, 1969).
Goals & The Self.......
Another point made by the notion of hierarchical organization concerns the fact that goals are not equivalent in their importance. The higher you go into the organization, the more fundamental to the overriding sense of self are the qualities
encountered. Thus, goal qualities at higher levels would appear to be intrinsically more important than those at lower levels. Goals at a given level are not necessarily equivalent to one another in importance, however. In a hierarchical system there are at least two ways in which importance accrues to a goal. The more directly an action contributes to attainment of some highly valued goal at a more abstract level, the more important is that action. Second, an act that contributes to the attainment of several goals at once is thereby more important than an act that contributes to the attainment of only one goal. Relative importance of goals returns us again to the concept of self. In contemporary theory the self-concept has several aspects. One is the structure of knowledge about your personal history; another is knowledge about who you are now.Another is the self-guides or images of potential selves that are used to guide movement from the present into the future. As stated earlier, a broad implication of this view is that the self—indeed, personality—consists partly of a person’s goals.
encountered. Thus, goal qualities at higher levels would appear to be intrinsically more important than those at lower levels. Goals at a given level are not necessarily equivalent to one another in importance, however. In a hierarchical system there are at least two ways in which importance accrues to a goal. The more directly an action contributes to attainment of some highly valued goal at a more abstract level, the more important is that action. Second, an act that contributes to the attainment of several goals at once is thereby more important than an act that contributes to the attainment of only one goal. Relative importance of goals returns us again to the concept of self. In contemporary theory the self-concept has several aspects. One is the structure of knowledge about your personal history; another is knowledge about who you are now.Another is the self-guides or images of potential selves that are used to guide movement from the present into the future. As stated earlier, a broad implication of this view is that the self—indeed, personality—consists partly of a person’s goals.
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