Specific External Stimuli Research Articles

T HE recent experimental interest in the subject of infant activity, notably by the students of Weiss at Ohio State University and latterly of Irwin at the State University of Iowa, has been confined largely to stimulus-response relationships. Pratt, Nelson, and Sun (22) investigated differentials of bodily activity in response to several stimuli, and Pratt (20, 21), Weiss (32), Stubbs (28), and Smith (27) have extended this work by way of refinement. The study of the nature of the bodily activity of infants irrespective of specific external stimulus sources was the task of Irwin, who gave objective data regarding variations under relatively controlled conditions, originally with four infants during the first ten days (4) and later with newborns during one interval between feedings (5). The importance of time since feeding as a factor inducing bodily activity was demonstrated in these experiments. Pratt (18) obtained a very low correlation between the activity of the infant and temperature within the cabinet. Irwin (5, 6, 7) was able to show also that weight and several length and cephalic measurements of newborn infants at birth were unrelated to amount of activity shown on the stabilimeter, as were certain indices of nutritional status, body surface, and intestinal surface. Certain studies of newborn infants in the field of metabolism wherein objective measurement of bodily activity has been made have provided a means of determining the relationship of other factors to bodily activity under fairly controlled external environment. It is the purpose of this paper to present certain reinterpretations of these data in so far as they may be pertinent to the study of bodily activity of newborn infants and its physiological concomitants. That muscular activity is an important factor in heat production was recognized by the earliest workers in the field of metabolism. Rubner and Heubner (25, 26) emphasized its importance, and the classic work of Benedict and Talbot (1, 2) with infants took this factor into account. The conditions necessary for studies of basal metabolism of absolute rest and

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