FUNCTION OF VIBRISSAE IN BEHAVIOR OF WHITE RAT 11 



response ; but applied with the same pressure to the nose, evokes 

 squeaking and vigorous head shaking.' 



Dr. Watson made some careful tests to determine the function 

 of the vibrissae in the formation of the labyrinth habit. He 

 first used a group containing two blind rats, two anosmic, and 

 two normal rats that had previously learned the maze. These 

 two were tested to make sure that the coordination was perfect 

 and then their vibrissae were cut close and they were given two 

 trials afterward. He found that there was marked disturbance 

 at first which lessened during the succeeding trials and which had 

 entirely disappeared twenty-four hours later. 



He then tested four other rats, cut their vibrissae, but did not 

 put them in the maze until forty-eight hours had elapsed, and 

 found but slight disturbance. His conclusions so far as the 

 labyrinth habit goes are as follows: — 



" First, under normal conditions the rat probably uses his 

 vibrissae to assist him in making proximate orientation in the 

 maze; second, in all probability the rat does not discriminate 

 his turns by means of any data contributed by the vibrissae; 

 third, the 'mmediate effect of the loss of the vibrissae upon the 

 ' steadiness ' of the rats reactions in the maze is only transitory — 

 the steadiness of the reaction being not at all affected if the rat 

 is allowed to habituate himself to the environment of his living 

 cage after the removal of the vibrissae." 



This is qualified by the following note in regard to the possible 

 use of the vibrissae under normal conditions: " Be it understood 

 however, that we have no crucial positive evidence in support 

 of this assumption. The evidence as it stands here proves 

 unquestionably that the animal is not disturbed by the removal 

 of the vibrissae if time is given him to wear off the unaccustomed 

 ' feel of their absence ' — but it does not give unequivocal positive 

 evidence that they are even nonnally used by the rat in sensing 

 openings, walls, etc."^ 



Miss Richardson in some experimentation with problem boxes 

 requiring the opening of a door in various ways concludes: 

 " The impulses furnished by the sense of touch seem to play an 

 important part in the adaptations of the animal to these several 



' Small, W. S.: Development of the Young White Rat, Am. Jour. Psychol. 

 1899, vol. 11, p. 82. 



'Watson, J. B.: Kinaesthetic and Organic Sensations, Psychol. Rev. Mon. Sup. 

 1907, vol. 8, no. 2, p. 75. 



