BEGINNINGS OF INTELLIGENCE 167 
is placed outside, the animal will probably make vigorous 
efforts to escape by clawing and biting in various parts of 
the enclosure, which are the usual instinctive methods em- 
ployed in similar situations. If the right movement is hit 
upon and the cat gets out and secures food, it will probably 
make its escape more readily than before when placed in 
the box a second time. After a number of trials the cat 
will come to make the right movements for escaping very 
soon after being placed in the box and its useless random 
movements will be discontinued. The connection between 
the perception of the mechanism of escape in the box and 
the act necessary to gain its liberty comes to be more and 
more firmly established in the cat’s brain with repeated 
experiences. The cat perceives a number of things in the 
box and performs a number of different acts, but out of - 
all these, associations are formed only between certain 
stimuli and those responses to them which bring pleasure 
to the animal. 
Pleasure and pain have apparently a fundamental con- 
nection with the development of intelligent responses out 
of instinctive activity. Were there not something to clinch « 
or strengthen the connection between certain stimuli and ° 
the appropriate responses to them the organism might per- 
form random movements till doomsday without being a 
whit better off. It is a problem therefore of fundamental 
importance to ascertain in what the mechanism of this 
ability to profit by experience essentially consists. It is 
not mere habit, not the mere making more permeable certain 
preformed connections in the brain. One act would then be 
just as apt to be followed up as another. Whether an act 
tends to be followed or not depends on what it brings to the 
organism. Apparently we have to do with a selective 
