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A BEHAVIORISTIC STUDY OF THE ACTIVITY OF THE 
RAT 
CURT P. RICHTER 
Pyschological Laboratory, The Johns Hopkins Hospital 
CONTENTS 
Introduction. 1 
I. Periodic nature of spontaneous activity. 4 
II. Relation of spontaneous activity to food... 8 
III. Relation of spontaneous activity to external temperature. 16 
IV. Relation of spontaneous activity to illumination. 20 
V. Relation of activity to age... 24 
VI. Persistence of rhythms of activity after withdrawal of rhythmic 
stimulus.• 31 
VII. On the origin of spontaneous activity. 36 
VIII. Relation of spontaneous activity to hunger. 48 
References. 54 
INTRODUCTION 
Interest in human psychology is moving rapidly toward prob¬ 
lems of general adaptation involving responses of the whole 
organism in actual working life-situations. This change of 
interest is due probably in large part to the healthy impetus 
given to psychological research by recent work and discoveries in 
the allied field of psychiatry. But, undoubtedly, it is also due 
to the strong influences from biology, especially that part of 
biology which is spoken of as behavior. 
This change of interest is probably more radical than it appears 
at first glance. It really represents an entirely different approach 
to things. The older psychology began with the study of the 
function of parts of the organisms, isolated responses (witness 
the work on sensations and memory) and then attempted to put 
these parts together. The error was made in neglecting the fact 
that the integration of parts often produces something—a novelty 
(Holt)—which could never be predicted from the study of the 
