382 JOHN L1NCK ULRICH 



explanations given above are based upon the establishment of 

 " sensory associations" of one form or another. In one instance, 

 increased sensory intensity can be brought about by establish- 

 ing an association of the senses by the production of the " success- 

 ful" movements and, in the other, definite sensory motor arcs can, 

 in an orderly way, be associated to produce the successful move- 

 ments. Some apparent differences may be thought to exist 

 between the two explanations, for the first may be said to result 

 in the establishment of " sensory associations," and the second 

 in the establishment of mechanical sensory-motor connections. 

 However, in reality, they appear to be the same, for sensory 

 excitations of a specific kind produce the " successful" move- 

 ments. It is the repetition of the " successful" act in both these 

 explanations of learning, which establishes " sensory association" 

 for that act, and, conversely, it is the repetition of the same sen- 

 sory excitations that produces repeatedly the " successful" move- 

 ments. In this theory emphasis on the repetition of an act with 

 its ultimate result, is clearly the substitute for pleasure-pain for 

 the retention of, or fixation of an act. One theory has the appear- 

 ance of being a mathematical psychological explanation, and 

 the other that of a mathematical physiological explanation for 

 learning. 



Other modified forms of the "trial and error" concept of learn- 

 ing exist. Holmes (3) offers as a substitute for " successful" 

 and "unsuccessful" movements other antithetical terms, con- 

 gruous and incongruous, in explanation for learning. The only 

 thing that is gained by introducing these terms is, that they em- 

 phasize the striking position of two sorts of movements, bringing 

 their relation to the fore and removing any necessity for intro- 

 ducing the "pleasure-pain" concept, with its incompatibility 

 with a physiological explanation for the fixation of movements. 

 The congruous movements bring solution to the problem and be- 

 come associated with other instinctive acts of a congruous kind, 

 and the "incongruous are discontinued, because they are in- 

 stinctive acts of an incongruous kind, antagonistic to the right 

 reactions, the congruous." Linking up of the "congruous" is 

 accomplished by reason of the existence of organic congruity of 



