PREFACE 
THE main purpose of this volume is to make accessible 
to students of psychology and biology the author’s experi- 
mental studies of animal intellect and behavior.! These 
studies have, I am informed by teachers of comparative 
psychology, a twofold interest. Since they represent the 
first deliberate and extended application of the experi- 
mental method in animal psychology, they are a useful 
introduction to the later literature of that subject. They 
mark the change from books of general argumentation 
on the basis of common experience interpreted in terms 
of the faculty psychology, to monographs reporting de- 
tailed and often highly technical experiments interpreted 
in terms of original and acquired connections between 
situation and response. Since they represent the point 
of view and the method of present animal psychology, but 
in the case of very general and simple problems, they are 
useful also as readings for students who need a general 
acquaintance with some sample of experimental work in 
this field. 
1*Animal Intelligence: An Experimental Study of the Associative Pro- 
cesses in Animals’ (’98), ‘The Instinctive Reactions of Young Chicks’ (’99), 
‘A Note on the Psychology of Fishes’ (’99),and ‘The Mental Life of the 
Monkeys’ (’o1). I have added a theoretical paper, ‘The Evolution of the 
Human Intellect,’ which appeared in the Popular Science Monthly in 1901, 
and which was a direct outgrowth of the experimental work. I am indebted 
to the management of the Psychological Review, and that of the American 
Naturalist and Popular Sciench Monthly, for permission to reprint the three 
shorter papers. 
Vv 
