INSTINCTS AND HABITS 243 



striking the glass plate. But in time he stopped darting after 

 the small fish. Later, the partition was removed; the pike 

 would always turn aside when he approached one of the little 

 fellows. Nothing now prevented his eating them except his 

 past experience. That is to say, new connections had been 

 formed in his nervous system, modifying his natural behavior. 

 200. Habit. The bruised pike shuns small fry ; a burnt child 

 dreads the fire. Acts which have unpleasant accompaniments 

 come to be avoided; the impulse to such action becomes re- 

 pressed. There is a positive side to this fact which is just as 

 important : acts that are associated with feelings of satisfaction 

 come to be performed more readily. This is the principle that 

 you would use if you tried to teach a dog or a colt a trick. If 

 you reward the animal with praise or a piece of sugar every 

 time it does what you want it to do, it will be more likely to 

 repeat the performance. At last it will reach a point where it is 

 easier to perform the trick than to do what was formerly 

 natural for it to do. 



Suppose that every time a baby cries for food the mother 

 calls to him before feeding him. At first the child will keep on 

 crying until something actually touches his mouth. In a few 

 days he stops crying as soon as he hears his mother's voice. 

 Some will say that the child recognizes his mother's voice, or 

 that he understands that she is about to feed him ; but from 

 similar observations and experiments with the young of many 

 animals, including babies, we should rather say that the sound 

 has become associated with the feeding and that the reflex has 

 been modified by this association. A new stimulus (a particular 

 sound) now serves as a substitute for the original stimulus to 

 stop the crying or to start the sucking. The new mode of re- 

 sponding, the new trick, the modified reflex, is called a habit. 

 If you will watch yourself and others for a day, you will 

 observe that most of our actions that are not reflexes are made 

 up of habits. Turning to the right on passing someone is a 

 habit. Taking off your hat on entering a house or a church, or 

 on meeting a lady, is a habit. These things do not come natu- 



