340 "Journal of Comparative Neurology and Psychology. 



problem becomes far simpler, and loses none of its importance 

 if it have to deal only with the possibility of establishing the pres- 

 ence or absence of a continuity of the third terms of the formulae, 

 stimuli — inner elaboration — reaction. Attempts to conduct experi- 

 ments for the sake of gaining knowledge of the intimate work- 

 ings ol the "inner elaboration" seem only to retard and unnec- 

 essarily to complicate the problem. If the complexity of a given 

 situation be definitely known, and if there be only one "most^de- 

 quate" reaction possible to that situation, these, and not inferred 

 psychic processes W\\\ enable us to give the reaction its continuity- 

 position. Of course, other objectively determined factors must 

 enter into consideration, such as the relative influence of instinc- 

 tive equipment and of experience. 



Returning to an interpretation of the results obtained from the 

 experiments just reported, it is required of us, then, to isolate such 

 reaction-types as appeared there. Of these, two stand out more 

 or less distinctly, (i) During the first 1 60 experiments, when only 

 the white pedal card was used, the animal showed an increasing 

 adequacy of reaction. Here, amongst several constant factors, 

 the most important experience-determinant (the white pedal cardj, 

 was the only one that made one situation different from another; 

 but in spite of its changing pedal relations, the white card, in its 

 direct sense-value to nose and eyes, was a simple, concrete, per- 

 sistently recurring experience-determinant. Innumerable obser- 

 vations, both in the laboratory and in everyday life, have shown 

 that dogs' experience-determined reactions are usually thus con- 

 ditioned, and that final unfailing and perfect adequacy of reaction 

 to such factors requires their frequent recurrence in situations 

 in which the animal is placed. (2) In the last 440 experiments, 

 where the directing sign board was used, the important experi- 

 ence-determinant was constant in principle, but not in direct sense- 

 value. A perfectly adequate reaction to the situation required 

 that, as the result of previous experience with a concretely dis- 

 similar situation, the dog be so influenced by the stimuli derived 

 from the sign board as to strike first and only the pedal bearing a 

 card which afforded him the same kinds of stimuli. A given sit- 

 uation was repeated only once in sixteen times, and no simple 

 associations could be of any positive assistance to him in guiding 

 him to the attached pedal; on the contrary, they only served to 

 mislead him. 



