THE RENAISSANCE OF PSYCHOLOGY 



tion modeled on physical concepts. E. H. Weber discovered 

 the variable sensibility of the skin by shov\^ing that a 

 pair of compass points pressed on the finger tips, separated 

 by an eighth of an inch, could be felt as tw^o, but had to be 

 separated three times as far on the back of the hand to get 

 the same effect. Thus it is found that the fine discrimination 

 of the human hand, along with the delicate guiding move- 

 ments of trained muscles, is the physiological basis of 

 skill. We carry a complete psychic map of our sensory 

 and motor equipment. That is the biological interest in 

 these early discoveries. Their academic pursuit led to the 

 formulation of the psycho-physic law, the real interest 

 of which is that it proves a psychological relativity. By 

 endlessly patient lifting of weights to determine which 

 was heavier as the differences were reduced, it was deter- 

 mined that an additional ounce in a pound felt as much 

 heavier as an additional two ounces in two pounds. Such 

 investigation played a leading part in Wundt's program 

 and led to studies of the reaction times of mental processes, 

 to studies in attention and association, in perception and 

 apperception. The psychophysical interlude absorbed the 

 academic mind; but its net issues were not momentous. 

 It neglected physiological interpretations though it en- 

 riched the experimental technique, which was destined 

 to become an important factor in the equipment for psy- 

 chological research. It was essential that psychology 

 should become experimentally minded. How the mind 

 gets its data has since become the indispensable starting 

 point for all psychology. 



The genetic vievsrpoint has a closer relation to the inter- 

 pretations that go to make the psychology of to-day; but 

 the progress of thought that is its history has diverse 

 origins. Its two foci are the child mind and the animal 

 mind; its body of doctrine constitutes comparative psy- 



[65] 



