Allen, Association in the Guinea Pi^. 



305 



the food is reached only one or two bites may be taken, and 

 then even if hungry, the guinea pig remains quiet. But if I 

 rattle paper or my keys during that time, or talk to it, it begins 

 to chew and continues to eat. 



The movements of the guinea pig are not well adapted to 

 climbing or jumping. As a rule it has a strong dislike to jump- 

 ing off a board to the floor of the cage. It will look around 

 and try every means of climbing down, and when compelled to 

 jump does so very awkwardly. On the other hand, it will run 

 off the edge of the table if left alone, and fall to the floor. If it 

 happens to have approached the edge very slowly it will not 

 fall ; but generally it seems to have not the least idea that the 

 plane surface upon which it runs does not extend over the 

 rest of the universe. In this too, however, there is indi- 

 vidal variation. It may be due to the inadequacy of vision. 

 The suggestion has been made by Dr. Watson that the differ- 

 ence between the rat and the guinea pig in this respect may be 

 due to a difference in the clinging power of the claws, and in 

 the sensitiveness of the feet to touch. At least it may be safely 

 concluded that the guinea pig has no sixth sense ^ which warns 

 it when there is danger of falling. 



Observations leads me to believe that vision in the guinea 

 pig serves primarily for orientation, and for detecting the pres- 

 ence of moving objects. I have not been able to formulate ex- 

 periments to determine this point definitely. All experiments 

 with colored cards, colored light, and distinctively visual stimuli 

 have given ambiguous, not to say negative results. 



The monocular vision which the guinea pig necessarily 

 possesses on account of the position of the eyes and the con- 

 figuration of the nose, undoubtedly prevents the clear differen- 

 tiation of objects at close range. There is no demonstrable 



' Small discusses the phenomenon as a "sense of support." He says that 

 all young land animals show hesitation when they approach a void {A'mr. [our. 

 Psychol.. Vol. XI, p. 80). Yerkes finds that there is a difference in the space 

 perceptions of tortoises, land species showing more hesitation when they 

 approach a void than water species. (Space Perception of Tortoises. /our. 

 Conip. Neurol, and Psychol., Vol. XIV, 1904). 



1 '3] 



*S..', 



C^ 



