Spaulding, Associatioi in Hermit Crabs. 5 i 



sent. "Correct path," as opposed to the incorrect, logically 

 implies in these experiments "aquarium" ; and its selection, as 

 shown by the ratio of improxement from day to day may, 

 though not necessarily, imply the representation of the con- 

 struct "aquarium," but it does demand the admission that acts 

 of recognition and discrimination, or even of what Lloyd Mor- 

 gan calls "perceptional inference" take place. These in turn 

 presuppose necessarily, as is well known, retention and pro- 

 duction. 



Carefully excluding the possibility of the crab's merely 

 following a path by smell, taste, or touch (although if it did 

 only this one could not account for a correct after an incorrect 

 choice had once been made) Yerkes found in one case that 

 after 40, in another that after 250, experiences no mistakes in 

 choosing were made. In a number of cases the subject turned 

 from, before it reached, the partition which blocked the pass- 

 age, thus showing the important part played by vision in direct- 

 ing the animal in the absence of smell, taste, and touch. All 

 of these, however, together with muscular sensations, Yekkes 

 concludes normally play a part in the formation of labyrinth 

 habits. These experiments therefore seem to show that upon 

 the basis of the "constructs" which one sense alone, viz., vis- 

 ion, give the crab, a consistent selection of the correct path is 

 possible ; but this is explainable it seems, even if it is consid- 

 ered that only a recognition of each successive part of that path 

 and consequentl)' a discrimination between it and the incorrect 

 is made, and )'et that no representation or ''reconstruction' of 

 "aquarium" takes place, although ot course this latter interpre- 

 tation is not excluded. 



A method of experimentation, however, which shows that 

 in the formation of a habit, or in the learning of a motor reac- 

 tion involving two sense fields, e. g., taste and vision, it is nec- 

 essary to overcome an instinct or tropism in the opposite direc- 

 tion, such a method, we think, would at least give more cogent 

 grounds for accepting the presence of representation than one 

 not doing this, although even here conservatism in making this 

 claim would be the safer course. 



