In the past, work has been done concerning the effect of mental activity on basal metabolism. Some investigators, Speck,1 Loewy,2 Johansson3 and Benedict and Carpenter,4 found a slight increase in the metabolic rate during mental activity. Grafe,5 in his monograph, also concluded that mental effort probably has an influence on metabolism.
The effects of strong emotional reactions on basal metabolism in the waking and in the hypnotic states have also been studied. Grafe6 mentioned a metabolism experiment in which intense sorrow increased the metabolic rate. Du Bois7 cited a similar observation brought on by anger. Like observations have been made by Hafkesbring and Collett,8 who noticed that harsh or sudden noises had a tendency to increase metabolism. Landis9 noted that strong emotions usually cause an increase in the metabolic rate. In his experiments, anticipation of a strong electrical stimulation raised the metabolism in the three persons tested, 6, 17 and