PSYCHOGENIC FACTORS IN MOTION SICKNESS 



389 



shocks during rotation (121). In this study, 

 an individual was regarded as sick if he re- 

 quested that the motion be stopped before 

 12 minutes. This criterion of sickness is 

 comphcated by the fact that an electric 

 shock is an annoyance by itself, and individ- 

 uals may have requested that the motion be 

 stopped not only because they felt ill, but 

 because they wished to avoid further shocks. 

 Of interest is the finding that there was no 

 relation between "neurotic" tendency and 

 susceptibility to motion sickness on the ro- 

 tating chair. Within the limitations of the 

 study it would appear that, if fear is an 

 important factor, it operates independently 

 of neurotic personality qualities. Of 14 in- 

 dividuals in the study who had no previous 

 history of motion siclcness, only 4 were made 

 sick upon rotation with shock. Of 14 other 

 subjects who had a history of motion sick- 

 ness, 6 were made sick on the chair without 

 the electric shock. It would thus appear that 

 the basic susceptibility of an individual was 

 relatively more important than his response 

 to the fear-inducing stimulus. The finding 

 that electric shock potentiates the appear- 

 ance of motion sickness would be most rele- 

 vant to first flights or the first day aboard 

 ship. In sea- or airsiclaiess, the repeated 

 exposure to the motions of the ship or plane 

 would reduce the element of fear through 

 familiaritj'' (43). 



Neurotic or Personality Maladjustment 



One of the early studies on motion sickness 

 reported that neurotic children who tend to 

 be car sick have an emotional association 

 with motion that has a significant effect upon 

 the appearance of symptoms (28). This re- 

 port prompted others to investigate the pos- 

 sibility of a relation between personality and 

 susceptibility to motion sicloiess. Many of 

 the studies of this type are subject to criti- 

 cisms that grow out of the difficulties of 

 obtaining adequate control subjects and also 

 for failure to recognize alternative explana- 

 tions. For example, men examined in a 

 Naval Hospital because of severe seasickness 



shortly after they had been discharged from 

 a ship are hkely to present an unusual picture 

 because of the loss of weight, which in some 

 cases amounted to 30 pounds or more during 

 the past war. The impact of the physical 

 debility plus the realization by the man that 

 he has not been able to perform his job 

 adequately can easily prejudice the examiner 

 into assuming he is dealing with a psycho- 

 logical and constitutional misfit. 



Observations on men sent to a Naval 

 Hospital because of seasiclaiess led one in- 

 vestigator to conclude that a large propor- 

 tion of the men severely affected by motion 

 sicloiess have neurotic complications (100, 

 101). Another study of men sent to shore 

 because of severe seasiclaiess was based upon 

 observations obtained after the men were 

 reassigned to shore duty. In the latter case, 

 the men had an opportunity to gain back 

 lost weight and the chance to perform a shore 

 job (17). Although there was a higher per- 

 centage of individuals with psychological de- 

 fects than might be expected by chance, the 

 proportion was much lower than that ex- 

 pected if severe seasickness were solely an 

 expression of emotional or neurotic defect. 

 It was also found that a history of motion 

 sicloiess correlated more closely with suscep- 

 tibility to seasickness than did neurotic tend- 

 encies as measured by a psychosomatic 

 complaint questionnaire prepared for use in 

 psychiatric screening. This result was based 

 upon the study of several groups of naval 

 personnel that totalled over 1,500 individ- 

 uals, including men aboard ship, men who 

 had completed tours of sea duty, and new 

 recruits (18). Fraser (33) reported similar 

 results in a study of 80 consecutive cases of 

 airsicloiess washouts. In this sample there 

 were 36 normal, 32 "neurotic," and 12 doubt- 

 ful cases of personal adjustment. Also wor- 

 thy of note was the additional observation 

 that, of 20 men grounded for psychoneurotic 

 disorders, none manifested airsickness, de- 

 spite the fact that two men had such severe 

 anxiety states that they had been reported 

 to lie on the floor of the aircraft incapable 



