46 JOSEPH PETERSON 



and of facilitation? These and many other problems not yet 

 solved have important bearings upon our knowledge of the learn- 

 ing act. But psychologists cannot wait for the solution of these 

 problems before attempting to formulate more satisfactory con- 

 ceptions of the processes with which they must deal at every 

 turn. It must be apparent that chaos now reigns with respect 

 to this matter. Some writers invoke imitation to explain most 

 modifications in behavior; others use pleasure and pain for the 

 same purpose; while ideas, purposes, the effects of random acts, 

 and so on, are freely used directly or indirectly by most writers. 

 All of these factors may have real parts to play in the learning 

 process, in some one or more of its various aspects, but they 

 are all more or less vaguely conceived and frequently erroneously 

 referred to, almost as some sort of original or spontaneous causes, 

 rather than complex aspects of the very thing that is to be better 

 understood and analyzed. Popular, educational, and sociologi- 

 cal writers may be forgiven for their own sins in this part'cular 

 so long as psychologists have nothing more satisfactory to offer 

 than at present. The great problem of how learning takes 

 place is yet largely unsolved. 



For the best progress, experiments in behavior modification 

 must go hand in hand with physiological investigations into the 

 nature of the nerve impulse. A few rather suggestive studies 

 have been carried out by psychologists upon the mutual effects 

 of successive acts on one another. It appears that while one 

 particular kind of act is being learned a second contrary one 

 is inhibited by it more than after the first has been completed. 23 

 The extensive investigations of Professor T. G. Brown, 24 on the 

 physiological side, have shown a summation of successive liminal 

 stimuli (facilitation) of intervals up to about ten seconds. Such 

 neural overlapping effects may well function to bring about a 



23 Pillsbury, discussing experiments on associative inhibition bv Muller and 

 Schumann (1894), concludes that " where several things are to be "learned in the 

 same connection, it is found that inhibition ceases to be effective if the first is 

 thoroughly learned before the second is begun." Fundamentals of Psychology, 

 1916, p. 359. See also p. 365. Especially interesting in this regard is a study 

 recently reported by Hunter,— Hunter, W. S., and Yarbrough, Jos. U. The In- 

 terference of Auditory Habits in the White Rat. Jour. Animal Behav., 1917, 7, 

 49-65. See especially pages 60 ff. One must be careful not to generalize too 

 much from these experiments on contrary acts. 



24 Brown, T. G. On the Phenomenon of Facilitation. I. Its Occurrence in 

 Reactions Induced by Stimulation of the "Motor" Cortex of the Cerebrum in 

 Monkeys. Quart. Jour, of Exper. Physiol, 1915, 9, 81-99. Other articles by the 

 same authority in the same journal. 



