382 



MOTION SICKNESS, I 



et al. (85). It would appear from the results 

 in Table IV that the roll rocker had a some- 

 what greater predictive efficiency than the 

 swing. About two-thirds of the men with 



TABLE III 



Correlation of Swing Reactions with 



History of Motion Sickness 



TABLE IV 



Correlation of Reactions to the 



"Roll Rocker" and History of 



Motion Sickness 



TABLE V 



Correlation of Reaction to a Swing 

 Test and to a Short Cruise at Sea 



Swing Reaction 



Unaffected 



Doubtful nausea 



Definite or marked re 

 action 



Total 



Sea Reaction 



Unaf- 

 fected 



21 



5 



33 



Nau- 

 seated 



Vom- 

 ited 



6 

 10 



24 



Total 



34 

 12 



20 



66 



a history of motion sickness displayed symp- 

 toms on the machine whereas a little less 

 than half the men with a positive history 

 had symptoms of motion sickness on the 

 swing. An even closer relation was reported 

 by Alexander et ah, between symptoms in- 



duced by a vertical accelerator and a ques- 

 tionnaire history of motion sickness (7) . In 

 this study, the vertical accelerator "sickness 

 rates" for subjects grouped according to their 

 previous history of motion sickness were as 

 follows: "susceptibles, 45 percent; inter- 

 mediates, 24 percent; non-susceptibles, 14 

 percent." The authors point out that their 

 findings were based upon controlled labora- 

 tory conditions and might, therefore, be 

 higher than would be obtained under operat- 

 ing conditions in the field. 



Seasickness and swing sickness were cor- 

 related in a study (54) of 66 men who were 

 tested on a swing and also taken to sea 

 (Table V). The investigators concluded 

 that the swing was of little practical value 

 as a preselection test for seasickness. It 

 would seem that they were unduly conser- 

 vative in their interpretation, since of the 

 32 men who had some positive reaction on 

 the swing test, 20 also had a positive reaction 

 to seasickness. 



Of a total of 1,000 swing tests in the AAF, 

 1 1 percent of the non-airsick flyers vomited, 

 in contrast to 65 jDercent of the airsick 

 eliminees (49). While Hemingway points 

 out that this is not perfect correlation, it 

 appears to be high enough to be of value 

 in screening procedures. 



Some of the objections to the determina- 

 tion of motion sickness susceptibility on a 

 swing or other device rest upon the difficulty 

 of retesting the men to get a reliable measure. 

 In one of the few quantitative studies of the 

 reliability of the swing test, Jasper et al. 

 (58) point out that 19 percent become sick 

 on only one of two test sessions. The cor- 

 relation obtained between tests 1 and 2 was 

 0.84 for 77 cases. It is likely that more 

 precision could be achieved in the determina- 

 tion of a threshold by improving the criteria 

 of onset of symptoms. 



Questionnaires 



Questionnaire forms have been developed 

 which require the person to indicate the 

 various forms of motion that have ever made 



