12 COMPARATIVE PHYSIOLOGY OF THE BRAIN 



operations on the brain. This would be throw- 

 ing out the wheat with the chaff. The mis- 

 take made by metaphysicians is not that they 

 devote themselves to fundamental problems, but 

 that they employ the wrong methods of invest- 

 igation and substitute a play on words for ex- 

 planation by means of facts. If brain-physiology 

 gives up its fundamental problem, namely, the dis- 

 covery of those elementary processes which make 

 consciousness possible, it abandons its best possi- 

 bilities. But to obtain results, the errors of the 

 metaphysician must be avoided and explanations 

 must rest upon facts, not words. The method should 

 be the same for animal psychology that it is for 

 brain-physiology. It should consist in the right 

 understanding of the fundamental process which re- 

 curs in all psychic phenomena as the elemental com- 

 ponent. This process, according to my opinion, is the 

 activity of the associative memory, or of association. 

 Consciousness is only a metaphysical term for 

 phenomena which are determined by associative 

 memory. By associative memory I mean that 

 mechanism by which a stimulus brings about not 

 only the effects which its nature and the specific 

 structure of the irritable organ call for, but by which 

 it brings about also the effects of other stimuli which 

 formerly acted upon the organism almost or quite 

 simultaneously with the stimulus in question (4). If 

 an animal can be trained, if it can learn, it possesses 

 associative memory. By means of this criterion it 



