\Vundt's principles are likewise three in num ber. (1) The principle of direct change of inner ration. This is but a different wording of what we have just discussed as the third principle of Darwin. It involves the principle of the heredi tary transmission of certain nervous connections; thus the reflex of weeping, which probably falls in origin under the third principle, has by inher itance come to take its place under the first. The transmission of a characteristic family physiog nomy or general expressive attitude is very com mon; and we invariably argue from the physical similarity to a similarity of mood, even though there be no possibility of imitation of the parents by the children. These direct changes in innerva tion are almost always accompanied by a notice able reactionary effect upon the ideational course of the emotion. The frightened man stutters, not merely because his tongue mechanically refuses service, but also because his thoughts are really brought to a standstill. (2) The principle of the association of analogous snsations is based upon the fact that sensations of similar feeling-tone easily associate and reinforce one another. This process forms the basis of the most characteristic of all emotive expressions, the 'mimetic move ments.' These are physiologically conditioned by reflex movements in and about the facial sense organs; thus the expression which stands for 'bitter' is an arrangement of the parts of the buccal cavity most sensitive to bitter in such a way as to prevent their excessive stimulation by the unpleasant taste. The 'sweet' expression. on the contrary. is that calculated to favor the con tinued stimulation of the tip of the tongue. the part most sensitive to sweet substances. By vir tue of the second principle these reactions have conic to appear in response not only to an ac tually bitter taste, hut also to an emotional con dition which possesses the same general feeling tone. So the expression has become symbolic. A wry face may denote a mental as well as a physical pain. (3) The principle of the connec tion of movement with sense ideas explains all the facial expressions and gestures which are not included under the two previous principles. Dere belong movements of the arms and hands. the
clenching of the fists in anger, and also certain facial expressions, such as the curling of the lip in scorn, and the staring eyes of surprise. The principle si.eins closely allied to Darwin's. first. It is not to be thought that any complex expres sion of emotion must be explained by a single principle. Such phenomena as laughing and weeping demand the use of all three principles for their elucidation.
dames proposes the five following principles: (1) The •cakencd repetition of movements formerly were of utility to the subject. This is equivalent to Darwin's first proposition.
(2) 7'he principle of reacting similarly to 114710 gnus-feeling stimuli. This is identieal with Wundt's second principle. (3) The principle of 'weakened repetition of movements which under other conditions were physiologically necessary fleets. The respiratory disturbances of anger and fear, e.g. may be considered as "organic reminis cences . . . of the blowings of the man making a series of combative efforts, of the partings of one in precipitate flight." (4) The principle of the mechanically determined idiopathic effects of the stimulus, i.e. the physiological outpourings of ex cess of nervous energy through the easiest drain age channels (ef. Wundt's first and Darwin's third law). (5) The principle of the mechanical perpetuation of emotional reactions which may be called accidental as for as their origin goes. For sonic of our emotional reactions no plausible rea son can be conceived. "In fact, in an organism as complex as the nervous system there must be many such reactions, incidental to others evolved for utility's sake, which would never themselves have been evolved independently, for any utility they might possess." In conclusion it may be said that no one of these explanatory series of principles is logically complete. There is need of further observation, and perhaps of a new construction of principles upon the basis of the psychology of action (q.v.). Consult: Darwin, The Expression of the Emotions in Man and Ani mals (London, 1890) Wundt, Grundziige der physioloifisehen Psychologie ( Leipzig, 1893 ) ; James, Principles of Psychology (New York, 1890) ; Titchener, Primer of Psychology (New York, 1899). See GESTURE.