Page:Philosophical Review Volume 2.djvu/87

Rh experiments, especially of those made by the bag method, seem cogent. The paper confirms well what we already know, — that our motor centres get objectively fatigued. The only things in it which seem to throw any really fresh light on the question of the seat of the effort-feeling, are, first, the experiments which show that when our muscles contract faradically we largely lose the sense of how much we lift; and, second, the observations on the rapidity with which laryngeal and other minute innervations must be measured out. The latter remark is (so far as I know) a novel one, and, if it could lead to experimental treatment, it might be very important. Müller ignores it altogether.

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Dr. Dessoir has undertaken a thorough investigation of cutaneous sensibility. The work will fall, when complete, into three chapters, treating respectively of the temperature sense, the sensations of pressure and contact, with the muscular sense, and the common sensations. The present instalment consists of the first of these three divisions, to which is prefixed a lengthy discussion (70 pp.) of sensation in general. It is with this preface that I propose to deal here.

What differentiates sensation from perception? The author passes in review various definitions and determinations of the two terms, (1) According to Helmholtz, sensation is a simple subjective modification of conscious content, the effect of the operation of external causes on our sense-organs; perception is comparatively complex. Dr. Dessoir takes decided exception to the predicate of subjectivity. (2) A widely spread view distinguishes sensation from perception by reference to the different participation of consciousness in the two processes. Such a determination is rejected, partly because of the indefiniteness of the word 'consciousness,' partly because of our ignorance of the connection between sensation-act and sensation-content. The former objection is to me less strong than it is to the author; and the raising of the latter seems needless from the psychological point of view. There are, however, others that might be urged. (3) Feeling has been made the determining moment. Or the sense-idea has been subdivided, the idea of the outer (perception) bringing always with it the idea of an inner (sensation or bodily feeling). Or the difference is a difference on the intellectual side: perception is sensation plus attention, or association, or consciousness, or memory-images. (4) The perception is complex,