178 BEGINNINGS OF INTELLIGENCE 



latter reinforces the first reaction. The pleasure-pain 

 response then resolves itself into the formation of associa- 

 tions. Withdrawing and defensive responses are usually 

 initiated by pain giving stimuli, and the instinctive or 

 random movement which brings a painful stimulus is in- 

 hibited under similar conditions in the future, not because 

 of the pain of its physiological correlate, but because it 

 comes to be associated with a withdrawing or defensive, 

 and hence an incongruous or inhibitory reaction. Pleasure 

 and pain thus interpreted have no mysterious power of 

 stamping in or stamping out certain associations. Whether 

 the result is reinforcement or inhibition depends on the 

 way in which a reaction and the secondary responses re- 

 sulting from the situation in which the organism is thereby 

 brought, happen to harmonize. 



The step from instinct to intelligence viewed as a physio- 

 logical process involves, therefore, no essentially new 

 element beyond the well known physiological properties of 

 the nervous system, and we are not committed to any par- 

 ticular hypothesis as to the physiological accompaniments 

 of pleasure and pain, or pleasantness and unpleasantness, 

 in order to understand how behavior may become adaptively 

 modified. How far the interpretation given will enable us 

 to explain the development of intelligence I do not pretend 

 to say. It may break down in attempts to apply it to 

 higher forms of learning, but it affords a useful working 

 hypothesis and takes us a way, I think, toward the solution 

 of our problem. 



BIBLIOGRAPHY 

 BAIN, A. The Sensations and the Intellect, 3d. ed., '94. 



The Emotions and the Will, 4th. ed., '99. 

 BALDWIN, J. M. Mental Development in the Child and in the Race. 



Methods and Processes, 2nd. ed., N. Y., '97. 



Development and Evolution, N. Y., '02. 



