EXPERIMENTAL PSYCHOLOGY. — The use of the experimental method in psychology—that is, making observations systematically, under precisely determined conditions in order to identify the causes of phenomena—followed upon the advances in the physiology of the nervous system during the first half of the nineteenth century. Johannes Mueller (1801–58), considered the founder of experimental physiology, stated in 1826 that the diversity of the impressions we receive from the different senses depends on an effect specific to each of them, and is not produced by the others (the optic nerve always gives rise to a luminous sensation, the auditory nerve always to an auditory sensation, whatever the manner in which it is stimulated).
E. H. Weber (1795–1878) discovered that the perceptible difference between two different weights, or between two lines of different lengths, is always related to the size of the objects under examination: a difference of a few grams is noticeable between two relatively light objects, but escapes us between two other objects having a greater weight. G. T. Fechner (1801–87), in his Elemente der Psychophisk (Leipzig 1860), further studied the relationship between the intensity of the stimulus and sensation, discovering that, while stimuli increase in geometric progression, the corresponding sensation increases in arithmetic proportion; and that the relationship between stimuli and sensations is therefore represented by a logarithmic curve. In less exact but more comprehensible terms, this means that, in order to have a sensation twice as intense as another, it is necessary to quadruple the intensity of the stimulus; this can also be understood reciprocally, namely, that the intensity of the sensation can be assessed from the intensity of the stimulus. In this way Müller experimentally studies the problem of sensory qualities, Weber that of comparing sensations of different intensity, and Fechner suggests the possibility of an exact measurement of sensation through the measurement of the corresponding stimuli. These, then, are psychological problems studied experimentally. This approach was reinforced by the studies of H. von Helmholtz (1821–94) on the speeds of the nervous impulse, in his classic works Physiologische Optik (1856–66) and Lehre von Tonenpfindungen (1863), which contain, in addition to fundamental physical and physiological data, a study of optical and auditory perceptions as well.
Wilhelm Wundt (1832–1920) published in 1873 the first systematic treatise on e. p., entitled Physiologische Psychologie, and in 1879 founded the first e. p. laboratory in Leipzig. For these two reasons Wundt is considered the initiator of e. p. Accepting the concept of sensation and association as it had been formulated by the English empiricists, from John Locke to James Mill and John Stuart Mill, Wundt aimed to discover the “psychological elements” and the laws governing their connection.
One year after the publication of Wundt’s Physiological Psychology, a small volume by the philosopher Franz Brentano (1838–1917) appeared: Psychologie vom empirischen Standpunkt, which was to exert a profound influence on e. p. Whereas Wundt confined his research to the “contents” of consciousness (sensations), Brentano emphasized the importance of the “acts” of consciousness that refer to the “contents”: the acts of ideation, judgment, feeling, desire, and decision. Oswald Külpe (1862–1915), initially Wundt’s assistant and later a professor at Würzburg, was also connected with Brentano. Through the research of his students, Külpe conceived and partially carried out an ambitious plan for the experimental study of the “higher processes,” of thought and will. Through his students (K. Stumpf of Berlin, C. von Ehrenfels and A. Meinong, Austrians), Brentano also prepared the ground for Gestalt psychology.
In the Anglo-Saxon countries, e. p. assumed a character of its own. Sir Francis Galton (1822–1911), profoundly influenced by the biological conceptions of his cousin Charles Darwin, may be regarded as the founder of the statistical method applied to biology and psychology. Convinced that the study of human nature is the prerequisite for human progress founded on scientific bases, Galton personally studied many psychological problems with a note of realism and practicality sharply contrasting with the somewhat theoretical tendencies of German psychologists. Galton also attempted to measure human abilities and individual differences and, in this respect, may likewise be considered the initiator of mental “tests.” William James (1842–1910), although he valued experimental research and had begun a small laboratory at Harvard in 1875 (thus preceding Wundt), exerted enormous influence through his Principles of Psychology (1890), permeated by a lively interest not only in scientific problems but also in those of concrete life, and enlivened by an incomparable style. William James opposed the atomism of the German schools and emphasized the importance of “action” in psychic life, as adaptation to reality and as an effort toward success. Following W. James, John Dewey and James Angell proposed a “functional psychology,” not in the sense of studying psychic functions as Brentano understood them, but as an interpretation of psychic activity “in function” of the needs of organisms.
“Behaviorism” derives from “functionalism”; it was advocated, beginning in 1913, by John Watson (born in 1878). Watson began his work with studies of animal psychology and, reacting against a certain mentality that indiscriminately attributed to animals psychological characteristics proper to human beings, maintained that, just as one can study the “behavior” of animals without resorting to facts of consciousness, so one can dispense with them in the study of human beings, founding psychology instead exclusively on the objective data of behavior, understood as a response to precisely determined stimuli. This extreme position gradually softened when Watson found himself obliged to take account also of verbal report (verbal behavior), which forced him to readmit, under a different name, much of the introspectionism that he had initially banished. Behaviorism stimulated experimental research and directed psychology toward the study of conduct and performance.
It should be recalled that, before behaviorism, Bechterew’s Objective Psychology (published in 1907) had proposed a psychology founded on external observation and on the concept of the “reflex.” Ivan Pavlov (1849–1940) confirmed this viewpoint with the doctrine of “conditioned reflexes.” In addition to innate reflexes, which are known as an obligatory response to a stimulus (the contraction of the pupil in bright light), Pavlov demonstrated the existence of “conditioned reflexes,” which occur not because a stimulus is suited to produce them, but because that stimulus has become effective on the “condition” that it has been presented together with a stimulus that is always effective. (For example, the cat runs at the sound produced by sharpening knives, not because this sound constitutes an obligatory summons for it, but because the sound has become associated with meat, which it may obtain.) According to Pavlov, conditioned reflexes are formed in the cerebral cortex and permit functional connections between areas that may be very far apart from one another. Although the work carried out by Pavlov’s school is highly valuable from a strictly physiological standpoint,
the question remains whether a fact that is passive by its very nature, such as the reflex, can truly be the cornerstone of all psychic activity.
Behaviorism, as well as certain principles of Wundtian psychology, was vigorously attacked by the Gestalt school (Gestaltpsychologie), founded in Germany by Max Wertheimer (1880–1943), Wolfgang Köhler, and Kurt Koffka, and subsequently transplanted to America, also as a result of the racial persecution that forced these scholars to leave Germany.
It is above all a vigorous reaction against psychological atomism, and maintains that psychology must turn to the study of total structures, which present themselves to our spontaneous observation, and to the system of internal forces that constitutes them as unities, without falling into the fictitious analyses of introspectionism, nor renouncing, as behaviorism has done, the value of introspection. When we see a square, it is the square that we see, and not the sum of its elements, that is, of the sensations corresponding to the elements into which we think we can decompose II. We see the “form” of the square even when the elementary “sensations” of which it should be constituted change: that is, we see a square whether it is outlined by four perpendicular lines, black, colored, or dotted, or is merely suggested by four isolated points in a characteristic reciprocal relationship. Gestalt psychology has made a valid contribution to the advancement of certain problems in psychology, especially those of perception.
A brief mention must not be omitted of the hormic psychology of W. Mac Dougall (1871–1937), which emphasizes as the distinctive characteristic of the psychical fact the active pursuit of an end or conclusion, and attaches great importance to the study of instincts. Hormic psychology and the psychoanalytic schools (v. PSICANALISI) have given a strong impetus to the study of affectivity and motivation.
The “mental tests,” or “mental reactives” (as De Sanctis proposed calling them), are tests (whether in the form of a question, problem, or task to be performed) devised in a simple and rapid manner to bring particular psychical functions or characteristics to light and evaluate their efficiency by comparing the performances of different individuals.
Mental reactives require a long process of preparation and testing on a large number of subjects in order to permit a measurement, however relative, of different psychical activities. In this sense they should be regarded as “products” and “instruments of e. p.”
It might seem that the great number of schools and the great variety of tendencies within psychology indicate its inadequacy to the task. This is partly true; but it is also true that, although there are many paths by which psychological problems are studied, and although not all reach their goal, all have contributed to a rapidly developing science, whose importance becomes increasingly compelling with each passing day. It should be noted, however, that e. p., in the strict and broad sense of the expression, has established itself as the naturalistic study of the human factor. With this limitation it would deliberately seek to avoid problems of a philosophical order, but it cannot always do so, and often introduces philosophical conceptions clandestinely, which must be evaluated and discussed. This is why it is desirable that psychology should be accompanied by a philosophy that understands its problems, accepts its results, and places them within a comprehensive conception of man.