Page:The New International Encyclopædia 1st ed. v. 10.djvu/675

INDIVIDUALITY. 589 INDO-CHINESE. the growth and extension of a part of the com- mon tissues of a parent. Imiividuality, in the psychological sense, which is different from the preceding biological and phj'siological meanings of the term, has reference to the personality of experience which is largely constituted by the continuity of the personal memory. Cases have not infrequently been re- ported where this memory continuum has been broken off and another instituted in its place, as the result of hypnotism or some form of disease. A person thus affected loses ail memory of pre- vious bodily existence, together with name, home, family, and friends, and begins a life so entirely new and different that he may be called another and different personality. The greatest number of personalities mutually ignorant of the exist- ence of others coimected with the same brain is five, in the case of Louis V., reported by Bourru and Burot in Variations de la personnalite (Paris, 1888). For further information, consult: Binet, Alterations de la personnalite (Paris, 1892) ; Janet, L'automatisme psychologique (Paris, 1889) ; James, Principles of Psychology (New York, 1890) ; Podmore, Studies in Psychi- cal Research (London, 1899). See Double Con- sciousness. INDIVIDUAL PSYCHOLOGY, or Differ- ential Psychology. Tliat branch of psychology which deals with the individual differences be- tween mind and mind, as distinct from general psychologv' (see Psychology), which deals with mental constants and uniformities. It thus in- cludes what Mill called 'ethology' and Bahnsen 'characterology.' though it is as much wider than this discipline as the concept of mind is wider than that of character. Its first principal problem is ( 1 ) to determine the range and nature of mental variations. This falls into two part- problems. The individual psychologist must (a) ascertain how and to what extent mental pro- cesses vary from one individual to another, and (b) trace the relation of the processes to one an- other in a single mind, thus discovering whether they are mutually independent, or whether there are certain fundamental processes upon which the rest depend. The answers to these two ques- tions form the contents of differential psychology proper. We have, however, further to inquire (2) into the conditions of the variations which we have established ; we must investigate the influences of heredity, climate, position in life, adaptation, education, sex, age, etc. And lastly (3) we must examine, classify, and explain the expressions of mental difference in handwriting, physiognomy, characteristic gesture, literary style, etc. The first of the three main problems is psy- chologically the most important. The observed differences between mind and mind have led. in the first place, to the elaboration of a doctrine of psychological tt/pes, which — seeing that the mind experimented on in the laboratory is always an individual mind — promises to be of value, not only for individual, but also for experimental psychology' (q.v. ). Practically all the more com- plex mental functions (ideation, attention, mem- ory, judgment, action, assimilation, constructive ability) evince typical differences. T'niess we take account of them we cannot adequately inter- pret our experimental results. Conversely, it is clear that the careful and exact work of the laboratory is peculiarly adapted to bring out the differences which individual psychology is seek- ing. More difficult is the second part of the problem: to determine the interrelation of the variable processes within a single mind. Here we have three methods at our disposal. The first is that of abnormal cases ; we may take ad- vantage of instances where there is extreme de- velopment or enfeeblement (perhaps even loss) of some processes, to study the resulting modifica- tion of other processes. We may ask, e.g. how loss of memory affects imagination, attention, power of observation, etc. The second is that of isolated variation; we may, by exi)erimental means, varj' a single mental process, and see if this variation involves changes in other processes in the same mind. The third is that of 'tests;' we choose in advance a number of processes for study, and proceed to examine them in a number of individuals, noting whether the individual differences in the selected processes run parallel to one another, and correspond in a regular man- ner. This correspondence or the lack of it will show the degree of correlation obtaining between the mental functions studied. The method is extremely laborious, but is at present more avail- able than any other, and should, in the long run, lead to valid results. Binet and Henri, e.g. sug- gest the following tests : ( 1 ) Memory : Visual memory of geometrical design, memory of sen- tences, musical memory, memory of colors and of figures. (2) Nature of mental images. (3) Imagination: Passive (finding fonns or faces in ink-blots), constructive (development of an essay theme), of design (composition or completion of a picture), and literar- (construction of sen- tences from given substantives or verbs). (4) Duration and range of attention. (.5) Compre- hension: Observation (analysis of a machine) and discrimination (definition of synonjins). (6) Suggestibility. (7) .Esthetic and moral sen- timents. (8) Muscular force and strength of will (persistence in muscular effort). (9) Motor skill and sureness of eye. Consult : Stern, Vcher Psychologic der indi- viduellen Differenzen (Leipzig, 1900), which con- tains a bibliography: Kraepelin, Psychologische Arheiten (Leipzig, 1896) : Titchener, Experi- mental Psychology (Xew York, 1901). INDO-CHINA. A geographical term former- ly designating the southeastern peninsula of Asia (Farther India), embracing Burma, Siam. French Indo-China, etc. INDO-CHINA, French. See Fbench Indo- China. INDO-CHINESE. The name applied as a general term to the great majority of the native population of Farther India, or Indo-China. It originally indicated that these peoples were re- lated by speech and physical characteristics to the Chinese, but in part also somatically and cul- turally to the peoples of Hindustan. The Indo- Oiinese peoples speak what are called 'tonic mon- osyllabic' languages, forming, with the Tibetan and Chinese groups, the extensive and important Sinitic or Tibeto-Chinese stock or family. The chief Indo-CTiinese peoples are the following: Burmese, Siamese. Annamese. Cambodians. Ton- kinese, who have all in some respects reached the status of civilization. Related to the Siamese are the other Tliai tribes. Shans and Laos, who preser-e (some of them, at least) the primitive type of the Thai stock better than the Siamese,