EXPERIMENTS ON TACTUAL SENSATIONS 

 IN THE WHITE RAT 



By EMORY S. BOGARDUS AND FREDERICK G. HENKE 

 From the Psychological Laboratory of the University of Chicago 



FOUR FIGURES 



The object of the present series of experiments was two- 

 fold: first, to determine if possible the function of the tactual 

 sensations of the white rat in learning a maze; and second, to 

 ascertain the effect of the running of previous mazes upon the 

 learning of subsequent alterations of the original maze by open- 

 ing and closing definite pathways. 



In previous experiments by Watson,' it has been shown .that 

 any one of the following senses may well be dispensed with 

 by the white rat in learning the maze : ( i ) vision — one series 

 of rats learned the maze in darkness, and another series with 

 eyes removed; (2) olfaction — the rats having been made anosmic 

 by an operation; (3) audition — sense of hearing temporarily 

 eliminated by filling the middle ear with paraffine; (4) cutaneous 

 sensation so far as vibrissae were concerned — vibrissae closely 

 clipped. While in the above tests no rats were deprived of 

 more than oiie sense at a time, Watson ^ also experimented with 

 a young male rat whose vibrissae had been clipped and which 

 at the same time was blind and anosmic. Notwithstanding 

 that a certain lack of tonicity was observable, and that errors 

 were eliminated more slowly, the rat learned the maze, and 

 finally became the usual automaton. It is obvious that while 

 these tests indicate that certain senses are not necessary for 

 learning the maze, they do not show what sense-factors are 

 normally utilized. Further, though Watson ^ anaesthetized the 

 nose of an anosmic rat and found that " successive reactions 

 w^ere not in the least disturbed," this experiment threw no 

 light on the significance of the cutaneous sensations in learning 

 the maze, since the animal had been previously trained. Like- 

 wise, although in these cases the vibrissae had been removed 



'Watson, J. B., Kinaesthetic and organic sensations: their role in the reactions 

 of the white rat to the maze. Psychological Revieic, Men. Sup., 1907, vol. 8, No. 2. 

 - Ibid., p. 98 f. 

 ' Ibid., p. 77. 



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