The Behavior of Organisms. An Experimental Analysis: By B. F. Skinner. New York: D. Appleton-Century Company, Inc., 1938. 457 pp.

This book is an important attempt to set up a science of behavior. It is in the best tradition of academic psychology. It is by a thorough worker with a real knowledge of the scientific method, and a keen critical mind which sees through the limitations of most of the approaches to problems of behavior. As a single example, he states, 'The need for quantification in the study of behavior is fairly widely understood, but it has frequently led to a sort of opportunism. The experimenter takes his measures where he can find them and is satisfied if they are quantitative even if they are trivial or irrelevant. Within a system exhibiting reasonable rigor the relative importance of data may be estimated and much useless measurement avoided. With a systematic formulation of behavior it is usually possible to know in advance what aspect of behavior is going to vary during a given process and what must, therefore, be measured. In the present case the following aspects of the system bear upon the problem of the measure to be taken: (1) the definition of behavior as that part of the activity of the organism which affects the external world; (2) the practical isolation of a unit of behavior; (3) the definition of a response as a class of events; and (4) the demonstration that the rate of responding is the principal measure of the strength of an operant. It follows that the main datum to be measured in the study of the dynamic laws of an operant is the length of time elapsing between a response and the response immediately preceding it or, in other words, the rate of responding.'

This passage is quoted at length because it gives something of the author's approach. His aim is a science of behavior which studies behavior as a subject matter in its own right. For the present he is well satisfied that it should be entirely descriptive and analytic. His experiments are based upon the Pavlov conditioned reflex but he emphasizes the importance of spontaneous behavior and driv