,.} E. L. THORNDIKE. 



etc. From among these movements one is selected by success. 

 But this is the starting point only in the case of the first box ex- 

 perienced. After that the cat has associated with the feeling 

 of confinement certain impulses which have led to success more 

 than others and are thereby strengthened. A cat that has 

 learned to escape from A by clawing has when put into C or 

 G a greater tendency to claw at things than it instinctively had 

 at the start, and a less tendency to squeeze through holes. A 

 very pleasant form of this decrease in instinctive impulses was 

 noticed in the gradual cessation of howling and mewing. 

 However, the useless instinctive impulses die out slowly, and 

 often play an important part even after the cat has had ex- 

 perience with six or eight boxes. And what is important in our 

 previous statement, namely, that the activity of an animal when 

 first put into a new box is not directed by any appreciation of 

 that box's character, but by certain general impulses to acts, is 

 not affected by this modification. Most of this activity is deter- 

 mined by heredity ; some of it, by previous experience. 



My use of the words instinctive d^xvA ifnpttlse may cause some 

 misunderstanding unless explained here. Let us, throughout 

 this book, understand by instinct any reaction which an animal 

 makes to a situation withoiU experience. It thus includes un- 

 conscious as well as conscious acts. Any reaction, then, to totally 

 new phenomena, when first experienced, will be called instinc- 

 tive. Any impulse then felt will be called an instinctive im- 

 pulse. Instincts include whatever the nervous system of an 

 animal, as far as inherited, is capable of. My use of the word 

 will, I hope, everywhere make clear what fact I mean. If the 

 reader gets the fact meant in mind it does not in the least matter 

 whether he would himself call such a fact instinct or not. Any 

 one who objects to the word may substitute ' hocus-pocus ' for 

 it wherever it occurs. The definition here made will not be used 

 to prove or disprove any theory, but simply as a signal for the 

 reader to imagine a certain sort of fact. 



The word impilse is used against the writer's will, but there 

 is no better. Its meaning will probably become clear as the 

 reader finds it in actual use, but to avoid misconception at any 

 time I will state now that impilse means the consciousness ac- 



