THE BIOLOGICAL BASIS OF THE ASSOCIATION OF 



IDEAS AND THE DEVELOPMENT OF 



PERCEPTION 



KNIGHT DUNLAP 



The Johns Hopkins University 



The first part of this paper was originally published in the 

 Johns Hopkins University Circular, March, 1914, pp. 25-41, un- 

 der the title Images and Ideas. It has proved to be not suf- 

 ficiently accessible, and my supply of reprints has become ex- 

 hausted, so that it seems necessary to republish in order to bring 

 it before those interested in this topic of growing interest, and to 

 make certain additions which are now pertinent. 



The two main and closely related points in this part of the 

 paper : the mechanism of the association of ideas, and the mech- 

 anism of the development of perception; were, I believe, first 

 presented in the article mentioned, although the scheme of the 

 development of perception is merely a generalization of well 

 known facts, and is substantiated by Pavloff s work on dogs, and 

 by similar work. The suggestion in regard to the association 

 of ideas is original; and in addition to supplying a long existing 

 gap, it has the merit of bringing this mental type of habit-forma- 

 tion into line with habit formation in general, thus conforming 

 to the scientifically imperative Law of Parsimony. 



It is not unimportant to point out that the general basis on 

 which the principles of mental habit-formation are here dealt 

 with, while it certainly is not in accord with the so-called " struc- 

 tural" or the " functional" or the " genetic" psychologies, as these 

 are usually understood, is nevertheless not " behaviorism," but 

 may well claim the designation of scientific psychology. It 

 starts with the empirical facts of consciousness as bound up with 

 the organic activity of the animal, and attempts to unite the 

 biological and the psychological data on the fewest and most 



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