CEREBRAL FUNCTION IN LEARNING 63 



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B. In the absence of certain evidence for the restriction of 

 the function of learning to special structures we may ask whether 

 there is any sort of nervous organization which is particularly 

 well adapted for learning, any structures whose functional 

 activity facilitates learning. The question is more complicated^ 

 than at first appears and should perhaps be stated in a different 

 way. Given equally strong incentives for learning and problems 

 equally well adapted to the innate equipment of the organism, 

 will learning take place any more rapidly because of the presence 

 of any special type of nervous organization? The mere demon- / 

 stration that animals with a complex cerebrum are capable of 1 

 learning complex problems more rapidly than those at a lower \ 

 evolutionary level will not answer the question. A bird will 

 learn to fly more quickly than a man and a man to speak more 

 rapidly than a bird, but these facts do not prove that simple 

 conditioned reflexes are formed any more rapidly in one than in 

 the other when the conditions of the experiment are adapted 

 to the two organisms. The rate of acquirement of complex 

 habits is dependent upon many factors besides the actual rate 

 of fixation of new integrations. The preexisting habits of the 

 organism, the number and variety of instinctive responses 

 available, the complexity of organization of existing reaction 

 systems, perhaps the mere number of unemployed association 

 fibers in the nervous system, all may influence the rate of learn- 

 ing, even though the underlying mechanism is the same. The 

 phylogenetic evidence is not sufficient to prove that there has 

 been any specialization of structure to facilitate learning. 



Such experimental work as bears on the question indicates I 

 a lack of any important specialization for learning. Destruc- I 

 tion of the frontal lobes is followed by loss of habits, yet animals \ 

 lacking the frontal lobes may learn as rapidly as normal onesj 

 (Franz, '02, '07). The slow improvement in human reeducation 

 after cerebral injury might be interpreted as proving the reverse, \, 

 but reeducation demands the establishment of an enormous'' 

 number of habits and the rate of improvement in the aphasic, 

 for example, can not be compared with that of a normal adult, 

 but only with that of the child first learning to speak. Measured 



