THE SUBCONSCIOUS 281 



The aim of physiological psychology is to clarify not only the 

 mechanism of consciousness, but also all of the antecedent and 

 subsequent physiological processes which are, from the stand- 

 point of an outside observer, demonstrably related to the con- 

 scious processes. It is possible, moreover, to develop a really 

 scientific introspective psychology in which abstraction is made 

 from all of these mechanisms and the individual experiences alone 

 are studied as given in consciousness. This makes up a large part 

 of general psychology. 



In behavior the difference between the parts 

 played by the reflex-instinctive activities of the brain- 

 stem mechanisms and the cortical control may be 

 further illustrated by an example (cf. Rivers, 1922). 

 The regulation of traffic on the streets of a large city 

 seems to go on largely automatically. Pedestrians, 

 motor cars, etc., move in orderly fashion without any 

 directing control because the rules of the road are 

 known to all and are obeyed habitually. Law and cus- 

 tom have fixed these modes of behavior much as in- 

 nate organization and long practice have established 

 in our own nervous systems at subcortical levels (or 

 at any rate below the level of attentive consciousness) 

 norms of reaction to familiar situations which go on 

 "of themselves." 



But at the rush hour in a great city at especially 

 congested corners one will find a traffic officer who 

 signals to each motor car separately when it shall 

 move and the direction to be taken. So in the more 

 complex adjustments of our daily lives the cortical 

 control of every step replaces the subcortical auto- 



