Review of O. Külpe's 'Grundriss d. Psychologie auf experimenteller Grundlage dargestellt'

This is a critical account of the results of the experimental method in psychology rather than an attempt to construct a system on the basis of those results. Psychology is regarded as an inductive descriptive science, differing from other sciences in the dependence of the experiments it describes on the experiencing individual. Dr. Külpe is chief assistant to Prof. Wundt at the Leipzig Institute, and his line of thought tends strongly to coincide with that of his teacher, but the deviations are frequent, and the book is much more than an abbreviated ‘Grundzüge der physiologischen Psychologie’.

In the general arrangement there are several interesting features. The first part deals with elements of consciousness, the use of the term ‘element’ being avowedly based on chemical analogy. The elements are divided into sensations and feelings; the former again into peripherally and centrally excited sensations, the subjects of memory and ideation coming under the. The second part treats of the connexions of elements, and these are divided into two groups, fusions (‘‘Verschmelzungen’’) and conjunctions (‘‘Verknüpfungen’’). In the chapters on conjunction of elements the spatial and temporal relations of mental phenomena are considered as a whole. This arrangement has much to recommend it, but the treatment of the extension and duration of sensations apart from their other properties, has some disadvantages. In the present case the phenomena of colour vision are considered in three different parts of the book, the important relations of tone and brightness coming under fusion, and the subject of contrast as depending on spatial and temporal relations under conjunction. The third part is entitled, ‘On Conditions and Consciousness,’ and is concerned mainly with attention. The anatomical and physiological details and the full descriptions of apparatus which make up so large a part of Wundt’s book are omitted or treated very briefly. In the chapters on sensation the special psycho-physical methods are fully considered, and there is a valuable discussion of the conditions of psychological experimentation; in fact, the author appears at his best when dealing with the difficulties and dangers of this process. In his account of the various senses Wundt is followed fairly closely and there is little which requires special mention. The observations of Blix and Goldscheider on temperature spots are rejected on the authority of Dessoir and because improbable on theoretical grounds; the latter reason does not seem quite worthy of the author. Fechner’s psycho-physical explanation of Weber’s law is decisively rejected, but the author does not regard the evidence as sufficiently conclusive to enable him to decide between the other explanations which have been advanced.

In the next division of the book, the customary term ‘memory image’ is discarded in favour of centrally excited sensation. The notion that these central elements are only weakened percepts, or, in the author’s language, renewals of the peripherally excited sensations, is regarded as having its only basis in the frequency with which it has been repeated by English psychologists and philosophers. The all sufficiency of association is also vigorously combated, chiefly on the grounds of the spontaneous origin of ideas and of the occurrence of mediate reproduction without an association of the reproduced and reproducing ideas having taken place. The appearance of a centrally excited sensation is regarded as dependent on general conditions, such as attention and feeling, and on certain special conditions. These are of two kinds, motives of reproduction and sources of reproduction (‘‘Reproductionsgrundlagen’’). The motives comprise the relations generally known as associations; when following the sensation α, the central sensation β arises, α is the motive for β. The sources of reproduction are peripherally excited sensations which must have existed in order that similar centrally excited should occur.

Feeling is regarded as a primary and independent element of consciousness, and the view that it is to be looked on merely as a property of sensation- the feeling tone- is rejected. Br Külpe recognises only two qualities of feeling proper, and sees in emotion a basis of one or other of these combined with organic sensations to which the emotion owes its special colouring. The question of an elementary feeling common to impulse, desire and will is considered, and the author sees in all three a common phenomenon closely related to feeling which he calls striving (‘‘streben’’). This common element is supposed to be a complex of organic sensations arising from tension of joints or tendons, partly of peripheral and partly of central origin. The central elements would correspond closely with the ‘feelings of innervations,’ but the use of this term is avoided as easily liable to misunderstanding. The large mass of experimental evidence on the physical accompaniments of feeling is help to point to the concomitance of heightened cerebral activity with conditions of pleasure and of lowered activity with conditions of pain. The second part deals with the connexions of the three classes of elements. Of the two groups of connexions, fusions are those which the qualities making up the complex are so blended together that they lose their individual character, fusion of tones being taken as the typical example. In conjunction, on the other hand, the individual qualities do not lose, or may even gain, in distinctness and may be easily recognised in the complex, colour contrast being the typical instance. In the section on fusion, the emotions are more fully considered. The author does not regard a satisfactory classification as possible but suggests as a basis the relative shares taken in the fusion by organic sensations and by feeling proper respectively. One end of a classificatory series would be formed by those emotions in which the organic sensation element is in excess; objective emotions such as surprise and expectation. At the other end would be those emotions in which the feeling element is more prominent; subjective emotions such as joy and sorrow. Fear, which may be regarded as a painful expectation, would occupy an intermediate position.

Under the heading conjunction (‘‘Verknüpfung’’), the subjects of space and time are considered. Dr Külpe distinguishes between spatial properties and relations; all sensations may have the latter; only visual and tactile sensations the former. Extension is the elementary factor of all spatial properties; distance, of all the spatial relations. The localisation of the right and left sides of the body is held to afford the most serious objection to Lotze’s doctrine of local signs, though the phenomena of metamorphopsia are regarded as very strong evidence of local signs in the case of vision. Wundt’s complex local signs are held to be more satisfactory than those of Lotze, but since these are fusions of sensations of movement with simple local signs, it seems hardly justifiable to apply Lotze’s term to them. Hering’s views on this subject are dismissed at once as unpsychological and unphilosophical. They have not been treated in so superior a manner by Stumpf and James, with whom the author concludes by finding himself most nearly in agreement. While regarding the semi-circular canals as organs for the maintenance of bodily equilibrium, the author holds that it is very doubtful that they give rise to spatially interpretable sensations, our estimation of position of the body depending rather on sensations having their origin in the joints and skin. We should thus have one kind of peripheral apparatus for maintaining equilibrium and another for appreciating it!

The parts of the book dealing with time are especially valuable. Külpe agrees with Meumann in depreciating the shares taken in the estimation of intervals by sensations of muscular tension on the one hand and by expectation and surprise on the other. The section on reaction time is very short, but is an excellent ‘‘résumé’’ of the experimental work on this question. The various difficulties attending the measurement of the compound forms are well estimated, and the results given seem rather a small return for the vast amount of work expended on this ‘Lieblingsgegenstano,’ as the author calls it.

The third part is short and devoted mainly to attention with sections on will and consciousness, sleep and hypnotism. The term ‘Apperception’ is adopted as signifying a process common to attention and will. This process is compared to the physiological function of inhibition, and, following Wundt, the physiological processes underlying it are supposed to take place in the frontal lobes. In support of this localisation several developmental and anatomical arguments are advanced. This localisation of so universal a process as Wundt’s apperception in any limited area of the brain is open to the gravest objections and draws attention to what must be regarded as the weakest aspect of the whole book, viz. its attitude to physiological problems. It has been a subject of reproach against physiologists that they have occasionally taken refuge in psychological explanations when their physiological resources have failed them. The author on the contrary seems to look on the dark corners of physiology as a means to escape when his psychological ingenuity reaches its limits. The section on the theory of centrally excited sensations is little more than an attempt to explain by having recourse to vague physiological assumptions. This is to a certain extent the logical outcome of the author’s standpoint that psychology has only to do with conscious processes; one is frequently reduced to the dilemma of having to seek an explanation either in unconscious mental processes or in purely physiological processes. The author’s confusion between physiological and psychological explanations cannot however be wholly ascribed to this difficulty. After considering Purkinje’s phenomenon in the light of certain physiological theories Dr Külpe goes on to say that it is nothing but a phenomenon of fusion, ‘that red and yellow are relatively bright, and blue and green are relatively dark colours, means in my opinion that the impression of yellow and red influences the conception of the pure brightness components so that their quality appears to be increased, while green and blue change their apparent brightness in the opposite direction’. The author here advances a purely psychological explanation of the phenomenon and naively says that in this way he avoids the physiological and physical difficulties which encumber the explanations of Helmholtz, Hering &c. Again in the section on feeling, the theories of Meynert and Wundt are criticised and compared. One in purely physiological, the other a purely psychological theory. The author is also inclined to seize somewhat uncritically on ‘new physiological discoveries,’ such as that of centrifugal sensory nerves which is used to explain hallucinations and other phenomena. It must be acknowledged that here the author is only following the lead of Wundt.

The many good qualities which the work possesses, however, far outweigh these defects. It is not too much to say that it is the best text-book of experimental psychology which has ever been written.