At any given time a human being is being acted upon by a wide variety of competing and contemporaneous stimuli. In walking down a street with a friend, for example, one may be attracted by the array of bright colors, of flowers, jewelry and clothing in the shop windows, blink one's eyes in the glare of the sun, feel a satisfaction in the presence of other people and a loneliness for a particular friend, dodge before a passing automobile, be envious of its occupant, and smile benevolently at a passing child. It would be difficult in so complex and so characteristically familiar a situation to pick out completely and precisely the original human tendencies at work, and trace out all the modifications to which they have been subjected in the course of individual experience. For even single responses in the adult are not the same in quality or scope as they were to start with. Even the simplest stimuli of taste and of sound are different to the adult from what they are to the child. What for the adult is a printed page full of significance is for the baby a blur, or at most chaotic black marks on white paper. But while it is difficult to disentangle out of even a simple, everyday occurrence the original unlearned human impulses at work, experimentation on both humans and animals seems clearly to establish that "in the same organism the same situation will always produce the same response." It also seems clear that in man these native unlearned responses to given stimuli are unusually numerous and unusually controllable. Upon the possibility of the ready modification of these original elements in man's behavior his whole education and social life depend. LEARNING IN ANIMALS AND MEN. Men and animals are alike not only in that they have in common a large number of tendencies to respond in definite ways to definite stimuli, but that these responses may be modified, some strengthened through use, and others weakened or altogether discarded through disuse. In both also the survival and strengthening of some native tendencies, the weakening and even the complete elimination of others, depends primarily upon the satisfaction which flows from their practice.