The Mental Life of the Monkeys 223 
the movement, (An adult human being whose hand was 
taken and made to push in a bar or pull back a bolt would 
thereby learn to do it for himself. Cats and dogs would 
not,and the monkeys are not proved to do so. | On the 
other hand, it is impossible for me to say, as of the dogs and 
cats, that the monkeys are proved not to do so. Ina few 
cases the animals did perform acts after having been put 
through them which they had failed to perform when left 
to their own trial and success method. -In the majority of 
cases they did not.) And in some of these latter cases fail- 
ure seemed so improbable in case the animal really had the 
power of getting an idea of the act and proceeding from idea 
to execution, that one is inevitably led to some explanation 
for the few successes other than the presence of ‘ideas.’ 
The general manner of making these experiments was like 
that in the case of the cats and dogs, save that the monkey’s 
paw was used to open the box from the outside instead of 
from the inside, and that the monkeys were also put through 
the acts necessary to operate some of the chute mechanisms. 
Tests parallel to that of comparing the behavior of kittens 
who had themselves gone into boxes with those who were 
dropped in by me were made in the following manner. I 
would carry a monkey from his cage and put him in some 
conspicuous place (e.g. on the top of a chair) and then give 
him a bit of food. This I would repeat a number of times. 
Then I would turn him loose in the room to see whether he 
had acquired an idea of being on the chair which would lead 
him to himself go to the chair. I would, in order to tell 
whether his act, in case he did so, was the result of random 
activities or was really due to his tuition, leave him alone for 
5 or ro minutes before the tuition. If he got on the chair 
afterwards when he had not before, or got on it much 
sooner, it would tend to show that the idea of getting food 
