392 



MOTION SICKNESS, I 



during various patterns of acceleration 

 should indicate whether a qualitatively dif- 

 ferent kind of afferent discharge arises under 

 conditions of motion sickness. This work 

 can also indicate whether the labyrinthine 

 receptors are mere passive recorders of the 

 stimulating conditions or whether the struc- 

 tural and functional aspects of these recep- 

 tors are such that they play an important 

 role in differences in susceptibility. Direct 

 electrical stimulation of the vestibular por- 

 tion of the eight cranial nerve is also a means 

 of determining the importance of temporal 

 pattern of stimulation. Further tracing of 

 the vestibular pathways in the brain is nec- 

 essary to strengthen knowledge about the 

 role of various portions of the brain in motion 

 sickness. 



Effort should be made to derive a quanti- 

 tative expression for the threshold stimulus 

 and to establish the stability and reliability 

 of such measurements. In contrast to the 

 single threshold value, another value repre- 

 senting an adaptability coefficient is needed. 

 Once a reliable measure of adaptability is 

 established, studies can be carried out on the 

 optimal conditions for creating adaptation. 

 Perhaps such experiments can be made uti- 

 lizing the analogies of conditioning experi- 

 ments, since adaptation resembles experi- 

 mental extinction rather than sensory 

 adaptation, according to present indications. 

 Since adaptation or extinction of motion 

 sickness at present seems rather specific, 

 attention might be given to experimental 

 methods of generalizing the phenomenon. 



Visual factors in motion sicloiess need fur- 

 ther analysis, since artifacts of head position 

 and movements have not as yet been satis- 

 factorily ruled out. The use of the artificial 

 horizon in this connection appears particu- 

 larly fruitful. Such instrumental control of 

 visual orientation may be used to supply 

 "true" orientation or "conflicting" orienta- 

 tion to determine whether or not vision may 

 act both in the role of an inhibiting as well 

 as a facilitating influence. 



A few well-controlled experiments are 



needed to examine more closely the relation 

 between susceptibility and personality fac- 

 tors. An attack can be made by exposing 

 to controlled motion individuals l-mown to 

 be severely upset psychologically, e.g., in- 

 stitutionalized psychoneurotics. The use of 

 independent judgments in assaying person- 

 ality factors is particularly important and 

 for that reason groups of persons already 

 categorized as to personality traits should be 

 employed as subjects. This would minimize 

 the effect of the experimental bias so often 

 pointed out as being important in this area. 

 Additional work on the role of fear and 

 suggestion should be done to establish the 

 range of effect that might result from these 

 variables on motion sickness. Fear of the 

 situation involving motion could be induced 

 by a variety of techniques, including in- 

 goctrination lectures and post-hypnotic sug- 

 destion. 



Applied research might be set up in situa- 

 tions where follow-up records are possible. 

 Such studies would permit the application 

 of several tests of susceptibility before ex- 

 posure to motion, e.g., aboard ship. Anal- 

 ysis of such information would permit a 

 retrospective estimate of the efficiency of the 

 criteria. Follow-up studies would give a 

 more accurate account of the incidence and 

 adaptability to motion sickness than now 

 available. 



Search for drugs to reduce motion sickness 

 should be continued, although studies should 

 also be made of drugs which facilitate the 

 appearance of motion sickness. It may 

 prove as valuable from theoretical grounds 

 to know drugs which facilitate motion sick- 

 ness as to know the inhibitors. 



Summary 



Motion sickness consists of a pattern of 

 symptoms including sweating, nausea, and 

 vomiting that occurs as a result of exposure 

 to periodic acceleration. More than 50 per- 

 cent of the general population may be made 

 motion sick. Such sickness is observed on 

 airplanes, swings, trains, and in numerous 



