MODIFIABILITY OF BEHAVIOE IN ITS KELATIONS 



TO THE AGE AND SEX OF THE DANCING MOUSE. 



ROBERT M. YERKES. 



From the Harvard Psychological Laboratory. 



With Four Figures. 

 CONTENTS. 



PAGE 



I. Introductory statements : the dancer as material for the investiga- 

 tion of problems of beliavior 237 



II. Relation of age and sex to rapidity of acquisition of a visual dis- 

 crimination habit 238 



III. Sensitiveness to electric stimulus, in its relation to age and sex. . . . 249 



IV. Strength of electric stimulus, in its relation to rapidity of habit- 



formation 252 



V. Relation of difficultuess of discrimination to rapidity of habit- 

 formation at different ages 255 



1. Experiments w^ith cardboards in discrimination box 255 



2. Experiments with discrimination box in dark-room 259 



3. Experiments with one side of discrimination box covered 



in varying degrees 263 



VI. Relation of age to rapidity of acquisition of labyrinth habits 265 



VII. Conclusions and summary 267 



I INTRODUCTORY STATEMENTS : THE DANCER AS MATERIAL FOR 

 THE INVESTIGATION OF PROBLEMS OF BEHAVIOR. 



The dancing mouse is well adapted, by its abundant and in certain 

 respects peculiar activity, to experiments on behavior. Taking 

 advantage of this fact, 1 have used it extensively as material for the 

 development of methods and the revelation of problems, both physi- 

 ological and psychological. That the results which have been 

 obtained are typically mammalian I am not prepared to assert. This, 

 however, is, for my immediate purposes, secondary in importance 

 to the methodological values of the work. Animal psychology is 

 urgently in need of exact methods of research. It is an appreciation 



The .TorjRNAL of Cojipat;ativi<; Nbiikology and rsvcriOLOGY. — Vol. XIX, No. 3. 



