Freeman, G. L. (1948). Neuromuscular Sets and Postures. In G. L. Freeman, Textbooks on psychology. Physiological psychology (pp. 393-417). Princeton, NJ, US: D Van Nostrand.
http://dx.doi.org/10.1037/11170-025
The term set has been used so often in psychophysiological theorizing that we forget it has never been adequately defined. As used in this chapter, it refers to an important class of organic variables, which are partially controlled by instruction, and which exercise a selective and determining influence over subsequent responses. While these variables are most easily identified with the pre-stimulus period, they accompany and frequently outlast the briefer response which they help to initiate and sustain. A fruitful physiological approach to the problem of set consists of measuring changes in the tensions of several muscle groups while the subject is anticipating and executing various performances. Neither an all-peripheral nor an all-central theory of set is tenable; instead a combination of the two views is suggested. The hypothesis is developed that "set" phenomena are expressions of the limiting effects of proprioceptive-tonic aspects of response upon exteroceptive-phasic activity. It is shown that at any moment the organism is exposed to a great mass of external stimuli, and that without some internal regulation there would be an indiscriminate diffusion of afferent discharge throughout the body. This regulation is presumably provided by a narrowing of the afferent flux into prepared reaction channels. The relation between tonic and phasic reaction systems becomes very complex and subtle at the higher levels of neural integration, and much further work is needed to test the hypothesis proposed. When this work is completed, it may be possible to regard the concept of set as physiologically superfluous and speak in more ultimate terms of neural facilitation, lowered thresholds, and altered potential gradients. Until that time, however, its use will serve to hold together phenomena having a common matrix and so remind us of a much neglected aspect of behavior. (PsycINFO Database Record (c) 2016 APA, all rights reserved)