412 



MOTION SICKNESS, II 



effectiveness of ship motion, although the 

 latter is characterized by comparatively low 

 accelerations. Such disparities lead one to 

 speculate on the possibility that the time- 

 course of the ship-imposed motion may have 

 etiological consequences bej^ond the effects 

 of labyrinthine stimulation, e.g., the estab- 

 lishment of an asynchrony between laby- 

 rinthine and other receptors (see above), 

 and the possible handicap which irregular 

 oscillations, as in a storm, may place on 

 adaptive processes.^^ 



Suggestions for Future Research 



Although the gaps in the physical knowl- 

 edge of the motion sickness phenomenon 

 have probably been evident enough from 

 the foregoing pages, it may be worth while 

 to reiterate them here in more organized 

 fashion. 



It seems quite evident that for the motion- 

 sickness problem and for other research 

 problems as well — e.g., those of naval archi- 

 tecture, amphibious tactics, etc. — a rather 

 extensive survey of the motions of various 

 types of vessels in various seaways would 

 be eminently worth while, and not too diffi- 

 cult or costly to make. Such data should 

 include continuous records of roll, pitch, and 

 scend, and it should be harmonically 

 analyzed in the manner of Deacon (8). The 

 correlation of such motions with sea condi- 

 tions^^ assumes special importance in view 

 of the recent advances in the forecasting of 

 sea conditions near shores (28). Any quan- 

 titative knowledge of ship motion should 

 find its way into the design of experimental 

 sickness-inducing machines, not only in the 

 interest of studying the effects of periodic 

 stimulation, but also in the investigation of 

 the "randomness" and phase-difference 

 effects cited above as possible etiological 

 factors. 



" See Abels, H., cited in referencs (20). 



18 "Average" sea conditions have, of course, 

 been investigated (see, for instance, the tabulation 

 of H. Johow, cited in the review by McEachern, 

 Morton, and Lehman, 18). 



Experiments of the sort carried out by 

 Steinhausen, Ross, Lowenstein and Sand, 

 and Adrian require great technical skill, but 

 they appear to be among the most satis- 

 factory ones for the purpose of elucidating 

 receptor mechanics and neural response. 

 On such preparations, for example, it would 

 be very profitable to study the effect of 

 oscillatory motion (which has, hereto, only 

 been calculated theoretically), and to settle 

 the important issue as to whether a canal 

 can be stimulated by purely linear motion. 

 The Adrian technique might be reapplied 

 to extend our knowledge of the correlation 

 between motion and the electrical response 

 of the otolithic apparatus, among other 

 things to learn whether response is two- or 

 unidirectional. On the theoretical side, it 

 appears worth while to formulate the motion 

 of linear vibrators (of the otolithic and 

 cupular type), disposed as they would be in 

 the human head of an individual aboard a 

 ship, and to calculate the o--values for the 

 conditions of the ship motion. This would 

 require only a simple extension of the con- 

 siderations of the second section above. 

 The author is not qualified to venture 

 opinions as to what particular approaches 

 would be most profitable in studying central 

 nervous phenomena, but only to acknowl- 

 edge the great obstacle to quantitative 

 description posed by present day ignorance 

 of such phenomena. 



The question of head position and sus- 

 ceptibility is an important practical one. 

 Aside from its connection with receptor 

 mechanics it might be worth while to study 

 it in the course of specific operations, such 

 as short transits in small landing craft (42), 

 or at certain stations. Not necessarily the 

 most immediately practical ones, but cer- 

 tainly the most basic studies in experimental 

 production of seasickness are those of the 

 type undertaken by Wendt. The author 

 would venture to guess that the interpreta- 

 tion of such experiments will be easier with 

 the aid of some theoretically-based analysis 

 of the kind suggested here, although the 



