228 The Animal Mind 



stimuli as clews. He arranged to have an ordinary electric 

 bell rung whenever the birds entered a wrong alley, and a 

 wooden bell sounded when they emerged and took the right 

 course. After they had learned the path under these condi- 

 tions, the two kinds of sound stimuli were interchanged, and 

 the result was a certain amount of confusion on the part of 

 the birds. Another device consisted of a board with electric 

 wires, laid on the floor of the labyrinth. A bell was rung 

 whenever a pigeon stepped on the board, and the bird was 

 given an electric shock; when the experience had been 

 repeated a number of times, the pigeons would show uneasi- 

 ness at the sound of the bell, wherever they happened to be in 

 the labyrinth (371). In white rats, Watson found that par- 

 tial deafness, produced by throwing the middle ear out of 

 function, had no effect on the ability of the rats to learn the 

 path (431). 



Various stimuli may, then, serve as clews in the process of 

 learning the labyrinth. But in certain cases, neither visual, 

 olfactory, nor auditory stimuli seem to be at all concerned. 

 This was true of Watson's white rats, and probably of Allen's 

 guinea pigs. Special tests were made to investigate the role 

 of tactile sensations in the labyrinth performances of these 

 animals. With the guinea pigs, a cardboard labyrinth was 

 substituted for that of wire netting, and a black cloth placed 

 on the floor (4). Watson's white rats, when the vibrissae 

 (long whiskers) were removed, learned the maze as well as 

 normal rats. Those which had already learned it manifested 

 some disturbance on having the vibrissae removed, showing 

 a tendency to bump into the partitions and hug the walls. 

 Watson does not report whether this same disturbance failed 

 to appear in the rats without vibrissae that were learning the 

 labyrinth for the first time ; he merely gives the times occu- 

 pied in traversing the course to show that the learning process 



