376 



MOTION SICKNESS, I 



is likely that the stimulus is a combination 

 of these two forms. (See Part II of this 

 chapter for additional details.) 



A close relation exists between the vesti- 

 bular apparatus and the autonomic nervous 

 system. Various phenomena associated 

 with the autonomic nervous system, other 

 than motion siclmess, e.g., vasomotor 

 changes and pupil dilation, may be seen in 

 animals upon stimulation of the vestibular 

 apparatus electrically, by hot or cold water, 

 or by acceleration (105). The role of the 

 higher brain centers in vestibularly induced 

 responses appears to be primarily an in- 

 hibitory one (120). 



Effects on Efficiency 



The undesirable effects of motion siclmess 

 upon efficiency of personnel have often been 

 dismissed as negligible, since few Navy men 

 fail to stand their watches during emer- 

 gencies because of seasickness. The excep- 

 tion to this is the group of men who are 

 seasick almost all the time at sea (100, 101). 

 Even one such individual may represent a 

 serious loss to a submarine because of the 

 specialized skills and limited number of per- 

 sonnel aboard. For this reason, captains 

 of submarines on War Patrols felt that men 

 sent to boats should be carefully screened 

 to eliminate any men who might be chronic- 

 ally seasick (30). 



There is some evidence that most individ- 

 uals who are made transiently motion sick 

 can exert themselves to the point of adequate 

 performance when the situation demands 

 (5). Such performance, which might be 

 called "peak efficiency," need not be closely 

 related to the performance of daily routine. 

 The latter might be called "maintenance 

 efficiency." Even though seasick, a man 

 may be able to exert himself to emergency 

 performance; the result of his efforts depends 

 to a significant extent upon how well he has 

 maintained his "gear." During rough 

 weather, seasick personnel lose interest in 

 doing anything except the barest necessities, 

 and an obvious lack of spontaneity can be 



observed aboard ship even in those men not 

 frankly seasick. Not only do the men fail 

 to indulge in the usual "horse play" and 

 spend almost all time off-watch in their 

 bunks, but they also fail to secure gear 

 properly. Such effects of seasiclaiess upon 

 "maintenance efficiency" should be seriously 

 considered as having a significant effect upon 

 personnel efficiency or performance. 



Criterion of Motion Sickness 



Every study of motion sickness has been 

 confronted with the issue of deciding when 

 a man is motion sick. It is obvious that 

 different results will be reported on the in- 

 cidence of motion sicloiess, or the beneficial 

 effect of some therapy, if a symptom such as 

 sweating is used as the criterion instead of 

 employing vomiting as the criterion of 

 motion sickness. The following is a general 

 outline of useful schemes to rate degree of 

 motion sickness: 



Motion Sickness 

 Rating 



No symptoms 



1 Slight nausea or other minor com- 



plaint 



2 Nausea and sweating 



3 Vomiting but able to work 



4 Incapacitated 



Only gross sweating, pallor, and vomiting 

 are observable without questioning the in- 

 dividual. Sweating may be detected by 

 means of skin resistance measurement em- 

 ploying a galvanometer (41). This tech- 

 nique, however, is limited largely to 

 laboratory conditions. The association of 

 sweating with motion sickness is much more 

 regular than are changes in blood pressure 

 and pulse rate (40, 41). Measurement of 

 blood pressure and pulse rate were reported 

 to be of little or no value in either estimating 

 severity of motion sickness or predicting 

 susceptible AAF personnel during exposure 

 to motion (40). A characteristic fall in 

 blood pressure was reported on a small group 

 of seasick men (104), but it is unlikely that 

 such changes are useful in estimating degree 



