Animal Behavior and Internal Drives

BY CURT P. RICHTER Psychobiological Laboratory, Phipps Psychiatric Clinic, Johns Hopkins University O NE of the most fundamental of all the phenomena which characterize animal life and distinguish it from plant life is the spontaneous motility of the animal organism. A few plants, to be sure, especially certain forms of marine vegetation, do move about, but these few are exceptions in the plant kingdom. The activity of animals, on the other hand, although it varies widely in form and extent from species to species, is an ordinary phenomenon which one always anticipates under normal circumstances. We may ask, then, what it is that sets off the diverse performances which animals display. Ordinarily we think of most of their activity as being due to some form of external stimulation. We know, however, that all animals, from the lowest. uni-cellular organism to man, are active even when all external stimuli have been eliminated. And since this spontaneous motility, just as any other kind of motility, must have a definite cause, it must be due to some natural factor within the organism. Many workers have chosen to call it "voluntary" activity, presumably because of the common belief that the "will" to do is the origin of the ction. We believe, however, that spontaneous activity arises from certain underlying physiological origins. We shall attempt to show from studies chiefly on the white rat what some of these origins are, and how they fit into the general biological picture of the animal's life. The investigations described below have been made by Ging H. Wang, Elaine F. Kinder, Tomi Wada, and the present writer in the Psychobiological Laboratory of the Phipps Psychiatric Clinic during the past six years. Some of the experiments have already been reported elsewhere, but we have taken this opportunity to collect also numerous observations that are as yet unpublished. Of the extensive work on animal "drives" done by Hoskins (i92.5), Moss (I924), Slonaker (I924, I92X5, I92.6), Stone (I92.4, I92.5, I92.6), Szymanski (i92.0, i92.2.), and Tracy (i92.6) we shall incorporate in this review only that part which bears directly on our own method of approach or on our own experimental findings.