PAPERS ON PSYCHOLOGY AND PHYSIOLOGY 125 



practice. These results were entirely in keeping with 

 the observation that whirling dancers and acrobats fre- 

 quently have a shortened after-nystagmus period and 

 that aviators of long experience likewise fail to show a 

 ''normal" nystagmus.^ Further work on the problem 

 was undertaken at the Psychological Laboratory of the 

 University of Illinois and the results of almost two years 

 of work have demonstrated that the ocular effects and all 

 the organic and mental effects of stimulation of the canals 

 tend to decrease in intensity and in duration and in some 

 cases to disappear.*^ It appears, then, as though the ocu- 

 lar effects are not inevitable reflexes and it is not possi- 

 ble, therefore, to use them as they have heretofore been 

 used in the clinical laboratory as an unequivocal index of 

 functional integrity. 



In supporting their contentions for the Barany tests, 

 the otologists appealed to fatigue and to the fact that any 

 temporary decrease was due to "gaze-fixing." In the 

 series of experiments reported in The Laryngoscope as 

 well as in our other experiments above mentioned, we 

 have sho"s\Ti that the appeal to "gaze-fixing" is not sat- 

 isfactory. For example, a group of white rats, which 

 have no organic provision for adequate fixation, were 

 rotated under conditions approximating those for human 

 subjects and in every case tlie nystagmus and the other 

 organic effects as well were found to disappear under 

 practice within from ten to eighteen rotational periods 

 of ten series each. 



In the case of fatigue, the clinicians have not been able 

 to cite any convincing evidence. On the other hand, we 

 have found the decrease which appears under practice 

 to carry over for long periods of time, thus proving that 

 the decrease is not due to temporary exhaustion. In 

 other words all of our experiments have gone to show 

 that nj^stagTQus is not a simple invariable effect of vestib- 



' See Parsons, R. P.. and Seger, L. H.. Barany chair tests and flying 

 ability. J. Aniei: Med. Ass., 1918, 70. 1064-1065. 



«See Griffith, C. R., The decrease in after-nystagmus during repeated 

 rotation. The Larynposcope, 1920. 30, 12S-137 ; The organic effects of repeated 

 bodily rotation, J. of Exper. Psycliol., 1920, 3, 15-46 ; An experimental study 

 of dizziness, ibid., 1920, 3, 89-125. 



