REFLEX ACTION 113 



will result in the secretion of saliva. In this way a stimulus that 

 originally had no effect upon the salivary glands has been associated 

 with one to which the glands did respond. As a result of this asso- 

 ciation, the previously indifferent stimulus becomes effective in 

 producing the reaction. A conditioned reflex has been established. 

 Experiments and analysis of conditioned reflexes make it clear 

 that a very large number of our adjustments are the result of such 

 correlations. Our responses to warning colors, signals, and 

 nationally used signs and symbols are all conditioned reflexes. 

 The same explanation holds for many more subtle and less widely 

 understood adjustments. 



This compounding of simple reflexes into alHed, antagonistic, 

 and chain reflexes, any or all of which may apparently be con- 

 ditioned, constitutes what is known as the " behavior " of the 

 animal. The study of certain fields of animal reactions has indi- 

 cated that behavior is dependent upon the " pattern " and 

 " order " of the reflexes. Pattern is used to indicate the number 

 of simple reflex arcs involved in the compounding and their locali- 

 zation in the nervous system. A study of pattern is essentially 

 one of the " morphology " of behavior, or the tracing of possible 

 pathways of transmission of impulses. The study of order 

 uncovers the time relations that exist in the succession of the 

 pattern elements or simple reflexes. 



It is generally recognized that certain forms of behavior, known 

 as instincts, are inherited. The nest-building and migratory 

 instincts of birds, for instance, can be explained only on the 

 assumption that both the pattern and the order of the reflexes in- 

 volved are inherited. Defense instincts of many young animals 

 furnish other examples of inherited behavior. Reactions called 

 emotions, such as fear, rage, and love, seem also to be illustra- 

 tions of the inheritance of both pattern and order. 



The consideration of behavior also involves a discussion of 

 habit. In habits, both the pattern and the order of reflexes are 

 acquired during the individual's lifetime. Habits of walking, 

 dressing and undressing, eating, and talking are examples in 

 which the pattern and order of reflexes may be determined very 

 early in hfe. In learning to manipulate a machine one establishes 

 reflexes of a particular kind and order. One has to make only a 

 superficial analysis of the routine procedure of operating an auto- 

 mobile, or writing on a typewriter, to trace the formation and 



