156 THE HUMAN BODY 



mankind, are higher than conceptions of family love; these in 

 turn rank above purely personal considerations. Personal con- 

 siderations which have regard to the future are higher than those 

 dealing only with the immediate present. The progress of civiliza- 

 tion is largely measured by the degree to which remote considera- 

 tions outweigh immediate ones in determining conduct. 



Because the cerebrum rests upon an underlying reflex mechan- 

 ism the tendency of the organism is always toward immediate 

 response to sensory stimulation; the hungry man tends to take 

 the first food that comes to hand ; the cold man tends to seek the 

 nearest available shelter. The action of associative memory, 

 when higher considerations dictate a different course, is to pre- 

 vent or inhibit the carrying out of the immediate response. In- 

 hibition is, then, one of the important functions of associative 

 memory. The man who deliberately does what he knows to be 

 wrong, acts as he does because his conceptions of right are not 

 powerful enough to inhibit the response to the lower stimulus. 

 The importance of inculcating the highest principles of right 

 living by training and example, during the receptive period of 

 the brain's development, is therefore clearly manifest. 



Habit Formation. Just as a single sensory impression re- 

 peated over and over becomes more firmly fixed in memory than 

 does one received only once, there seeming to be some sort of 

 impression upon the remembering nerve-cell which becomes 

 deeper at each repetition of the stimulus; so every interaction of 

 associative memories in determining a course of conduct leaves 

 a track upon the cells involved, which is deepened by repetition 

 of the same series of memories leading to the same conduct. One 

 of the strong tendencies of the brain is to arrange its associative 

 memories thus in groups leading to certain definite responses. 

 It is this tendency which lies at the basis of habit formations.* 



Habits which are formed in this way, by repeated following 

 of the same line of thought to the same actions, take on much of 

 the character of simple reflexes. A stimulus which arouses the 

 chain of associative memories results in immediate carrying out 



* The term habit is used here with reference to those acts which we do 

 habitually because of having done them so often before, not with reference 

 to habits which are based upon perverted or diseased conditions of the body, 

 such as drug or liquor habits. 



