ALMOST any infant can be made to cry by presenting very loud sounds; indeed, nearly any form of stimulation-cold, heat, hunger, pain-will cause crying if the stimulus is very intense. Contrariwise, weak or mild stimuli will not ordinarily cause crying.WATSON, in the article which follows, shows how a previously ineffective stimulus can be made effective through conditioning. The student should relate this experiment to Pavlov's work which is described in Chapter VI. Watson is best known as the founder of behaviorism, a point of view which argued that only behavior, not consciousness, could be studied scientifically.IN REGENT literature various speculations have been entered into concerning the possibility of conditioning various types of emotional response, but direct experimental evidence in support of such a view has been lacking. If the theory advanced by Watson and Morgan to the effect that in infancy the original emotional reaction patterns are few is correct, then there must be some simple method by means of which the range of stimuli which can call out these emotions and their compounds is greatly increased.