46 Animal Intelligence 



more quickly. Here, too, accident may play a part, for a 

 cat may merely happen to be attending to its paw when it 

 claws. The kind of acts which insure attention are those 

 where the movement which works the mechanism is one 

 which the cat makes definitely to get out. Thus A (O at 

 front) is easier to learn than C (button), because the cat 

 does A in trying to claw down the front of the box and so 

 is attending to what it does; whereas it does C generally 

 in a vague scramble along the front or while trying to claw 

 outside with the other paw, and so does not attend to the 

 little unimportant part of its act which turns the button 

 round. Above all, simplicity and definiteness in the act 

 make the association easy. G (thumb latch), J (double) 

 and K and L (triples) are hard, because complex. E is 

 easy, because directly in the line of the instinctive im- 

 pulse to try to pull oneself out of the box by clawing at 

 anything outside. It is thus very closely attended to. 

 The extreme of ease is reached when a single experience 

 stamps the association in so completely that ever after the 

 act is done at once. This is approached in I and E. 



In these experiments the sense-impressions offered no 

 difficulty one more than the other. 



Vigor, abundance of movements, was observed to make 

 differences between individuals in the same association. 

 It works by shortening the first times, the times when the 

 cat still does the act largely by accident. Nos. 3 and 4 

 show this throughout. Attention, often correlated with lack 

 of vigor, makes a cat form an association more quickly after 

 he gets started. No. 13 shows this somewhat. The ab- 

 sence of a fury of activity let him be more conscious of what 

 he did do. 



The curves on pages 57 and 58, showing the history of 

 cats i, 5, 13 and 3, which were let out of the box Z when 



