Modification by Experience 281 



learning. Watson (767) showed that rats deprived of 

 sight, hearing, smell, and touch (the vibrissae or long 

 whiskers being removed and the paws made anaesthetic), 

 could learn the maze. Yerkes (820) demonstrated that 

 the Japanese dancing mouse does not necessarily depend 

 on sight, smell, or touch for guidance. On the other hand, 

 Vincent's (747-749) experiments show that a maze in which 

 the true path was painted black and the wrong paths white, 

 or vice versa, was learned more quickly than an ordinary 

 maze ; that one in which the true path was smeared with 

 beef extract and cream cheese alternately (the two odors 

 being used to prevent olfactory adaptation) gave a greater 

 total accuracy ; and that in a maze without sides, that is, 

 an elevated pathway, the rats were much disturbed by 

 the loss of the accustomed contact with the walls. Dif- 

 ferent animals are undoubtedly unlike in the use they make 

 of sensory cues. The frog studied by Yerkes (805) in a 

 very simple labyrinth showed a disturbance in its habit 

 when red and white cards placed on either side of the pas- 

 sage were interchanged. The pigeon (647), when required 

 to go through a labyrinth in darkness, was obliged to relearn 

 it. On the other hand, Small found that altering the direc- 

 tion of the light had little effect on the performances of 

 his white rats. He also placed wooden pegs painted red, 

 at each division of the paths, in the middle of the correct 

 path, and caused the maze thus arranged to be learned by 

 untrained rats. They did not learn it any faster because 

 of the presence of these visual hints, nor, when it had been 

 learned, were they at all discomposed by the removal of 

 the pegs (684). Allen's (4) guinea pigs did not alter their 

 behavior when the position of colored cards in the maze 

 was changed. Rouse (647) found that the pigeon could 

 make use of auditory stimuli as cues. He arranged to have 



