Some psychologists have regarded pleasurable and unpleasurable feelings, not as collective terms including a great variety of simple feelings, but as entirely uniform, concrete states, so that, for example, the unpleasurableness of a toothache, of an intellectual failure, and of a tragical experience are all regarded as identical in their affective contents. Still others seek to identify the feelings with special sensations, especially with cutaneous sensations and muscle-sensations. Such entirely untenable assertions require no criticism. They indicate, however, the uncertain state of the doctrine of feelings, even at the present time.

10. The question has been raised whether or not particular physiological processes correspond to the simple feelings, as is the case for the sensations. Older psychology was inclined to answer this question in the negative, and to contrast the feelings as inner, purely psychological, states with sensations as processes aroused from without. In modern times, on the contrary, the affirmative answer has generally been given, but for the most part without the support of adequate empirical proof. Obviously, our assumptions in regard to the physiological phenomena accompanying the feelings must be based on [p. 86] actually demonstrable physiological processes, just as our assumptions in regard to the physiological conditions of sensations were deduced from the structure and functions of the sense-organs. In looking for such processes, it follows from the subjective nature of the feelings, that we should not expect to find them among the processes produced in the organism directly by external agents, as the sensations are, but rather in reactions which arise indirectly from these first processes.

The observation of compounds made up of affective elements, that is, of emotions and volitions, whose easily perceptible concomitants are always external movements or changes in the state of the organs of movement, also points in the same direction.

The analysis of sensations, and of the psychical compounds derived from them, makes direct use of the impression-method; while the investigation of simple feelings, and of the processes resulting from their combinations, can employ this method only indirectly. On the other hand, the expression-method, that is, the investigation of the physiological reactions of psychical processes, is especially adapted to the examination of feelings and processes made up of them, because as shown by experience, such reactions are regular symptoms of affective processes. All the phenomena in which the inner state of the organism is outwardly expressed, may be utilized as aids for the expression-method. Such are, besides the movements of the external muscles, especially the respiratory and cardiac movements, the contraction and dilation of the blood-vessels in particular organs, the dilation and contraction of the pupil of the eye, etc. The most delicate of these is the beating of the heart, which can be examined as exactly reproduced in the pulse of some peripheral artery. All other phenomena are generally wanting in the case of a simple feeling. It is only for high intensifies, where the feelings always pass into [p. 87] emotions, that we have other, added symptoms, especially changes in respiration, and mimetic expressive movements.