Experimental Psychology
Experimental Psychology
(1) Experimental psychology in the widest sense is the application to psychology of the experimental methods evolved by the natural sciences. In this sense virtually the whole of contemporary psychology is experimental. The experimental method consists essentially in the prearrangement and control of conditions in such a way as to isolate specific variables. In psychology, the complexity of subject matter is such that direct isolation of variables is impossible and various indirect methods are resorted to. Thus an experiment will be repeated on the same subjects with all conditions remaining constant except the one variable whose influence is being tested and which is varied systematically by the experimenter. This procedure yields control data within a single group of subjects. If repetition of the experiment with the same group introduces additional uncontrolled variables, an equated control group is employed. Systematic rotation of variables among several groups of subjects may also be resorted to. In general, however, psychologists have designed their experiments in accordance with what has frequently been called the “principle of the one variable.”
A distinction is frequently drawn between two observational methods in psychology(a) introspection which appeals to private data, accessible to a single observer (see Introspection), and (b) objective observation of public data, accessible to a number of observers among whom there is substantial agreement (see Behaviorism). These two methods, though they are often regarded as disparate, may perhaps be more properly regarded as the extremes of a continuum of observational objectivity, many varying degrees of which can be found in psychological experimentation.
(2) The term experimental psychology is also used in a more restricted sense to designate a special branch of psychology consisting of laboratory studies conducted on normal, human adults as distinguished from such branches as child, abnormal, differential, animal or comparative, social, educational and applied psychology. This restricted sense is employed in the titles of text-books and manuals of “experimental psychology.” Included in this field are such topics as sensory phenomena, perception, judgment, memory, learning, reaction-time, motor phenomena, emotional responses, motivation, thinking and reasoning. This identification of experimental psychology with a specific type of content is largely a result of historical accident, the first experimental psychologists were preoccupied with these particular topics.
The historical antecedents of experimental psychology are various. From British empiricism and the psychological philosophy of Locke, Berkeley and Hume came associationism (see Associationism), the psychological implications of which were more fully developed by Herbart and Bain. Associationism provided the conceptual framework and largely colored the procedures of early experimental psychology. Physics and physiology gave impetus to experiments on sensory phenomena while physiology and neurology fostered studies of the nervous system and reflex action. The names of Helmholtz, Johannes Mller, E. H. Weber and Fechner are closely linked with this phase of the development of experimental psychology. The English biologist Galton developed the statistical methods of Quetelet for the analysis of data on human variation and opened the way for the mental testing movement; the Russian physiologist Pavlov, with his researches on “conditioned reflexes,” contributed an experimental technique which has proved of paramount importance for the psychologist. Even astronomy made its contribution; variations in reaction time of different observers having long been recognized by astronomers as an important source of error in their observations.
The first laboratory of experimental psychology was founded at Leipzig in 1879 by Wundt, who has been called “the first professional psychologist.” With such research as that of Stumpf on sound; G. E. Mller on psycho-physics, color and learning; Ebbinghaus on memory; and Kulpe and the Wrzburg school on the “higher thought processes,” experimental psychology made rapid strides within the next two decades. In America, the chief standard bearer of Wundtian psychology was Titchener. Among the others who were instrumental in the introduction and development of experimental psychology in America, may be mentioned James, Hall, Mnsterberg, Cattell, and Watson.
Johannes Mller, Elements of Physiology, 1834-40.
E. H. Weber, De Tractu, 1851.
G. T. Fechner, Elemente der Psychophysik, 1860.
W. Wundt, Principles of Physiological Psychology, 1873-4.
G. T. Fechner, In Sachen der Psychophysik, 1877.
G. E. Mller, Zur Grun&egung der Psychophystk, 1878.
G. E. Mller, Die Gesichtspunkte und die Tatsachen der Psychophysichen Methodik, 1904.
E. B. Titchener, Experimental Psychology, 1905.
Frobes, Lehrbuch der Experrmentellen Psychologic, 3rd ed., 1923.
E. G. Boring, History of Experimental Psychology, 1929.
— L.W.