x SOME EXPERIMENTAL RESULTS 189 



business in hand, and perhaps with one strong pull get 

 the bolt out. In this way the time may suddenly rise 

 from twenty seconds to five or six minutes, and the rise 

 really signifies nothing but a slight failure in persistence. 

 Nevertheless, I generally took the time when I could get 

 a time keeper, as there are cases, particularly where " trial 

 and error " play a large part, in which it can be made 

 instructive. In the main, I relied on taking notes of 

 everything that seemed essential at the moment. What 

 an animal does is far more important for our purposes 

 than the time which it takes to do it. 



My original aim being to measure the influence of 

 perceptual acquisition (learning by perception of results) 

 as distinct from motor acquisition (learning an act by 

 doing it) I tried to find things for the animals to do in 

 which accidental success was improbable. It is no easy 

 matter to devise problems which combine this feature with 

 that of being clearly within the competence of the animal 

 physically and mentally. Some experiments I discarded 

 when I found them opening a door to accidental success. 

 Others I went on with for the sake of collateral problems, 

 without regarding them as instances of learning by 

 perception. Those which do seem to indicate perceptual 

 acquisition are of unequal value, some being more and 

 others less open to the suggestion that the success may 

 have been accidental. 1 



4. Description of experiments. 



(i) Pulling string. 



My first experiment was with my cat Tim, a small black 

 torn, rather more than a year old. It was repeated with 

 my dog, Jack. 



Tim is a sociable creatute, who follows his friends about in the 

 half dog-like way that some cats have, but as a psychologist he 

 has two great defects. His attention is of the most fickle order, 

 and what is even worse, he gets his meals at the most irregular 

 times, and by methods known only to himself. It is therefore 

 impossible to say beforehand whether he will take any sustained 

 interest in the proceedings at all. He will not put himself out 



1 I was throughout trying to find methods quite as much as results, and 

 I have given a somewhat full account, even of experiments which prove 

 little, in the hope that the methods used may be suggestive to others. 



