The observation that expectation of events, pleasant or unpleasant, may cause physiologic response is not new. Mouths watered at sight of food, faces blanched at approach of danger, hearts missed beats in amorous anticipation long before science took an interest in these phenomena. Nonetheless, when physiologists, having taken a closer look, demonstrated the effect of sudden danger on the discharge of adrenalin and that of the sight of food on digestive secretion, they made medical history. The names of Cannon and Pavlov are not soon to be forgotten.
Applying Pavlov's experiments on dogs to man, Carlson1 observed that a subject with a feeding gastrostomy secreted gastric juice in response to chewing appetizing food, even though the food never entered his stomach. Subsequent studies by other investigators confirm this observation. Gastric juice is secreted within five minutes of sham-feeding, in an act of physiologic expectation.
Now, 50 years after Carlson's