A popular topic for psychological discussion, but a relatively unexplored field of research, has been the often suggested relationship between muscular processes and temperament. Since temperament is so generally regarded as a component of personality, the latter term is most frequently employed as the postulated correlate. Many years ago James (11) spoke of the explosive and obstructed types of personality, of which the former was supposedly associated with hyperactivity of the skeletal musculature and the later with hypoactivity. Later Davenport (3) wrote of hyperkinesis and hypokinesis and certain apparent relationships to temperament. Downey (4) also assumed similar relationships and attempted to measure individual differences in motor activities. In addition to these observations by psychologists it is almost commonplace in lay thought to relate differences in personality to individual differences in muscular activity, muscular tension, or neuro-muscular energy. Witness such descriptive terms as bundle of nerves, restless, jittery, fidgety, jumpy, nervous, tense, and energetic, which are used not only to describe personalities but which are commonly related among themselves and to other manifestations of personalsocial behavior differences. Not the most uncommon relative, but perhaps the most obscure, is emotional tension. The experimental literature bearing directly upon the problem is not large. In 1928 Johnson (12) cited data suggesting a relationship between overt muscular tension and individual differences in temperament. Duffy (5, 6), following her work, found that for a group of nursery-school children tension upon a hand dynamometer during a task correlated 0.52 with ratings of excitability made by teachers and physicians. Freeman and Katzoff (7) employed the same measure of tension and correlated the rank score with ranks of fifty college subjects' own ratings of their annoyance to sixi irritating conditions introduced during the task of reading. A coefficient of 0.49 was found. Lee (13) studied the relationship of adult and child scores on the Woodworth-Mathews questionnaire to measures of standing steadiness and knee-jerk amplitude (supposedly an indirect measure of muscular tension). She found no evidence of relation to the latter, and only slight relationship to the former. Seham (21), however, believes his data from normal children and those with functional disorders show the latter to be less steady on the Whipple test; and he shows in another study (22) that motor restlessness is slightly more prevalent in the abnormal subjects. A comprehensive study which bears indirectly upon the problem is that of Darrow and Heath (2). From 23 measures of physiological reaction to stimuli and from responses to neurotic and introversion-extroversion questionnaires, physiological syndromes and personality constellations were developed. While none of the resulting correlation coefficients was large, the authors conclude that these groups of variables may be arranged simultaneously in two continuously overlapping series, both characterized by something akin to hypo-reactivity at one extreme and hyper-reactivity at the other. Perhaps most insistent concerning the relationship between muscular processes and emotional unstability is Jacobson (10). He reports marked success in treating chronic cases of neurasthenia (which he terms neuromuscular hypertension) with his technique of progressive relaxation. The present paper approaches this general problem from a slightly different avenue. Recently the writer (25) submitted a criticism of Pavlov's (19) concept of internal inhibition. It was argued that much of the behavior which