A group of twelve persons selected only on the basis of their visual defects were exposed to stressful Coriolis accelerations under standardized conditions. All demonstrated differences in susceptibility to acute motion sickness that bore no relation to their rank order of visual deprivation. Insofar as comparison with a group of normal subjects was made possible, no significant differences in susceptibility were demonstrable. It was concluded that vision is not an essential but rather a secondary etiologic factor in the genesis of motion sickness. This is not incompatible with the fact that symptoms characteristic of motion sickness may be visually induced in the absence of 'motion.' (Author).

A group of twelve persons selected only on the basis of their visual defects were exposed to stressful Coriolis accelerations under standardized conditions. All demonstrated differences in susceptibility to acute motion sickness that bore no relation to their rank order of visual deprivation. Insofar as comparison with a group of normal subjects was made possible, no significant differences in susceptibility were demonstrable. It was concluded that vision is not an essential but rather a secondary etiologic factor in the genesis of motion sickness. This is not incompatible with the fact that symptoms characteristic of motion sickness may be visually induced in the absence of 'motion.' (Author).

A group of twelve persons selected only on the basis of their visual defects were exposed to stressful Coriolis accelerations under standardized conditions. All demonstrated differences in susceptibility to acute motion sickness that bore no relation to their rank order of visual deprivation. Insofar as comparison with a group of normal subjects was made possible, no significant differences in susceptibility were demonstrable. It was concluded that vision is not an essential but rather a secondary etiologic factor in the genesis of motion sickness. This is not incompatible with the fact that symptoms characteristic of motion sickness may be visually induced in the absence of 'motion.' (Author).

Motion sickness susceptibility of five labyrinthine-defective (L-D) and 25 normal subjects was tested under the force environments encountered in parabolic flight (0 g and hyper-g). The L-D subjects were uniformly symptomless, while the normal subjects revealed great inter- and intra-individual differences in susceptibility to motion sickness provoked by standardized head movements during: (1) the hypergravic and (2) the weightless phases of the parabolic maneuver while restrained; and (3) the weightless phase while being rotated in a chair. Four of six subjects tested under condition 1 were completely unaffected by the condition while two reacted with symptoms. Condition 2 provoked severe symptoms in five of the twelve subjects tested and moderate symptoms in one. Fifteen subjects tested under condition 3 revealed either a marked increase or decrease in susceptibility to Coriolis acceleration in weightlessness compared to terrestrial baseline measurements. (Author).

Nineteen normal persons and three deaf subjects with bilateral loss of labyrinthine function (L-D subjects) were exposed to Coriolis accelerations during the brief periods of weightlessness in parabolic flighy by having them move their heads while rotating in a Barany chair at 30 rpm. None of the L-D but all of the normal subjects except three experienced motion sickness: Only one of eight subjects selected on the basis of insusceptibility to symptoms in standard parabolic flights was free of symptoms; the other seven were motion sick and completed on the average only six parabolas. Two of three subjects selected primarily on the basis of low susceptibility to Coriolis acceleration in a slow rotation room were symptom free, and one was motion sick but his level of symptoms did not reach the end point of severe malaise during ten parabolas. In addition to demonstrating susceptibility to motion sickness when exposed to Coriolis acceleration in the weightless phase of parabolic flight, the findings are important in emphasizing the difficulty in predicting susceptibility to motion sickness in novel force environments. (Author).

The onset of motion sickness is characterized by a decline in generalized feelings of well-being. In this study, an attempt was made to quantify these subjective changes during the experimental production of motion sickness in the Slow Rotation Room. A simple eleven-point rating scale was used to measure the well-being state. The nature and the time of onset of symptoms were recorded independently. Systematic relationships were obtained between the amount of stimulation required to produce the Malaise 111 endpoint and the rate of change of well-being. In general, relatively susceptible individuals showed on immediate decline in well-being at the onset of the stimulus which continued to fall sharply until the endpoint was reached. With increasing resistance to motion sickness, this point of rapid decline ('avalanche phenomenon') was proportionately delayed. The point on the rating scale at which this rapid decline began was relatively consistent across all subjects. Various positions along the well-being scale were consistently associated with specific constellations of symptoms. The recovery of well-being, following the cessation of the stimulus, appeared to be slower in individuals of low susceptibility than in those who were highly susceptible. (Author).

The Coriolis (motion) sickness susceptibility index (CSSI) of 275 healthy male subjects was calculated from data obtained by a standardized laboratory procedure at each of five specific levels of motion sickness severity, viz, frank sickness (FS), severe malaise (M III), moderate malaise (M IIA and M IIB), and mild malaise (M I). The stressor value (E factor) of a single standardized head movement associated with each rotational rate of the test chair was adjusted to yield an equivalent CSSI score independent of the endpoint selected. Close agreement among the CSSI scores obtained at each endpoint was found in intercorrelations, test-retest reliability coefficients (N = 30), and frequency distributions that reflected the orderliness and stability in the appearance, ramification, and intensification of the acute symptomatology evoked in progressing from M I to FS. The endpoint M IIA appeared, however, to yield the best balance between subject acceptability and test confidence, and was used without exception to calibrate the motion sickness susceptibility of 250 additional subjects. (Author).

The effectiveness of a drug in reducing susceptibility to acute motion sickness is readily determined in a slow rotation room (SRR) where the stressful Coriolis accelerations are under quantitative control and the experimenter and subject can collaborate under laboratory conditions. Fifty subjects were used, each serving as his own control, in evaluating 16 representative antimotion sickness drugs. Only the drugs with a sympathomimetic or parasympatholytic action and some of the antihistamines were notably effective. The summation effect of dextroamphetamine sulfate and 1-scopolamine hydrobromide provided far better protection than any single drug. Other classes of drugs had either a slightly favorable or slightly unfavorable action. (Author).