PSYCHOLOGY, EXPERIMENTAL. A compre hensive term for those phases of mental science which are variously called 'the physiological and It may be defined as the exact science of mind (see PsvcnoLoGi), and as such is not a department of nate with other departments, but rather a chology dominated by a certain method. Kant said, in his Metaphysisehe Anfangsgriinde der Naturwissenschaft, that psychology could never be a science: (1) Because mental process has but one dimension (time), and where you have but one dimension you cannot apply mathematics to your i.e. cannot handle it scientifically; (2) because no sane person would submit himself to your psychological ments, even if you devised then]; and (3) because the employment of psychological method, or trospection (q.v.), changes the objects upon which it is directed, and so precludes the bility of uniform results. Kant was, however. blinded by his a priori assmnptions; he shared with the great German philosophers since nitz (q.v.) a hearty contempt for the faculty of or (see FACULTY) ; and he was unduly impressed by the worthlessness for science of the chologies of his own day. Hence he could not see, as we do, that wherever in the past there had been scientific discussion of the facts and laws of perception, and of the physics and physiology of voluntary action, important contributions had been made to a future science of experimental psychology. Indeed, it is only in the latter half of the nineteenth century that the three Kantian objections have been finally answered, and that psychology has taken rank as a science among the sciences.
The argument that mathematics is inapplicable to mental processes was brilliantly met by hart (q.v.), who pointed out that our inner experience shows differences not only of duration, but also of intensity. and expressed the course of ideation, as a function of these two variables, in a series of mathematical formulae. 'mathematical is now out of date; the method that he, as a pioneer. followed has not stood the test of time. But his service to
the cause of mental science is none the less real and enduring. The second and third objections have been overcome by the work of Fechner and \Vundt (qq.v.), whose E/cmcnic dcr 1'sltclo phll.sik ( Leipzig. 18(i0) and der physi ologischen, Psychologie ( 4th ed., Leipzig, 1893) niark epochs in the development of the new chology. No one could urge, after the publication of the Psychophysik, that psychological experi mentation with human subjects was impossible. Fechner experimented, systematically and cessfully, with himself and with others, upon a long list of special prohlems, and the methods which he prescribed are those employed in psychophysieal investigations. \Vundt put the matter beyond the reach of controversy by his foundation of the first psychological laboratory (q.v.) at Leipzig in 1879. Wundt appears. fur ther, to have been the first to use the phrase 'experimental which occurs in his Beitruge ur Thcorie der Sinnestrahr•nehnang (1862). His services both to psychology proper and to psychophysics can hardly be ed. We have to note here. in particular, his in sistence that the psychological experiment cc In sists simply in a carefully guided and rigidly controlled introspection, i.e. his refutation of third objection. A single instance must suffice. "The says Moult. "contains in it no reference to the organs by whose exter nal or internal stimulation it has been aroused; it tells us nothing of the character of its stimuli; it conies to us as a simple quality, giving no hint of any means whereby we might define that qual ity more In other words, the sensation is its hare qualitative self, devoid of all objective reference. \\lien we remember that the sensation of the faculty psychology, as of the Eng lish empirical psychologists, has always been a hit of sense-knowledge, a mental state of process that informs us of something in the outside world. we see what all advance in insight and scientific method is implied in \Vundt's formula tion.