WHAT IS THE EXPERIMENTAL ANALYSIS OF BEHAVIOR? 1

been regarded as a contradiction in terms. Living organisms were distinguished by the fact that they were spontaneous and unpredictable. If you saw something move without being obviously pushed or pulled, you could be pretty sure it was alive. This was so much the case that mechanical imitations of living things?singing birds which flapped their wings, figures on a clock tolling a bell?had an awful fascination which, in the age of electronic brains and automation, we cannot re capture or fully understand. One hundred and fifty years of science and invention have robbed living creatures of this high distinction. Science has not done this by creating truly spontaneous or capricious systems. It has simply discovered and used subtle forces which, acting upon a mechanism, give it the direction and apparent spontaneity which make it seem alive. Similar forces were meanwhile being discovered in the case of the living organism itself. By the middle of the seventeenth century it was known that muscle, excised from a living organism and out of reach of any "will," would contract if pinched or pricked or otherwise stimulated, and during the nineteenth century larger seg ments of the organism were submitted to a similar analysis. The dis covery of the reflex, apart from its neurological implications, was essentially the discovery of stimuli?of forces acting upon an organism which accounted for part of its behavior. For a long time the analysis of behavior took the form of the dis covery and collection of reflex mechanisms. Early in the present century, the Dutch physiologist Rudolph Magnus m, after an exhaustive study of the reflexes involved in the maintenance of posture, put the matter this way: when a cat hears a mouse, turns toward the source of the sound, sees the mouse, runs toward it, and pounces, its posture at every stage, even to the selection of the foot which is to take the first step, is deter mined by reflexes which can be demonstrated one by one under exper imental conditions. All the cat has to do is to decide whether or not to pursue the mouse; everything else is prepared for it by its postural and locomotor reflexes. To pursue or not to pursue is a question, however, which has never been fully answered on the model of the reflex, even with the help of Pavlov's principle of conditioning. Reflexes?conditioned or otherwise? are primarily concerned with the internal economy of the organism and with maintaining various sorts of equilibrium. The behavior through which the individual deals with the surrounding environment and gets from it the things it needs for its existence and for the propagation of the * A Sigma Xi National Lecture, 195&-1957. 343