Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.561466
Title: Motion sickness with Earth-horizontal translational and rotational oscillation presented in isolation and in combination
Author: Joseph, Judith Anoushka
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2008
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Abstract:
Low-frequency Earth-horizontal translational and rotational oscillations can cause motion sickness in transport. Previous studies have found that motion sickness depends on the frequency, magnitude, direction and duration of the motion, however, knowledge of the mechanisms of motion sickness is far from complete. The concept of sensory conflict – that motion sickness arises because of a conflict between sensed and expected sensory information is central to theories of motion sickness, but little is known about how the physical characteristics of motion influence sensed and expected sensory signals. The aim of this research was to advance understanding of the effect on motion sickness of factors which may influence sensed and expected vestibular signals during exposure to low-frequency translational and/or rotational oscillation. The first experiment investigated whether motion sickness depends on the phase between combined lateral acceleration and roll oscillation at 0.2 Hz. The roll oscillation had one of four phases relative to the lateral acceleration: 0° delay, 14.5° delay, 29° delay, and 29° advance. Sickness decreased as the delay in the roll motion increased; less sickness occurred with a phase advance than a phase delay, suggesting that motion sickness cannot be predicted from the acceleration in the plane of the seat. The second experiment investigated how motion sickness varies between four 60-minute exposures of 0.1 Hz combined lateral and roll oscillation which involved different combinations of a high and low magnitude motion: LLLL, HHHH, LHHL and HLHL. The high magnitude motion produced greater sickness than the low magnitude motion. For the two variable motion conditions, there was no significant difference in accumulated illness ratings when the motion sickness dose values were the same. In the third experiment, 0.2 Hz roll and pitch oscillation were studied at three displacements: ±1.83° ±3.66° or ±7.32°. A trend for motion sickness to increase with increasing displacement was observed; similar sickness was caused by roll and pitch oscillation at each magnitude. In the fourth experiment, subject head displacement was measured during 0.2 Hz fore-and-aft oscillation with and without a backrest at three magnitudes: 0.22, 0.44, and 0.89 ms-2 r.m.s. Illness increased systematically with increasing magnitude of oscillation with a backrest, but less systematically without a backrest, suggesting an interaction between the effect of motion magnitude and the influence of a backrest. There were no significant differences in illness with or without a backrest at any of the magnitudes studied. Between subjects, there was little evidence to suggest that greater fore-and-aft and pitch displacement of the head was associated with an increase in motion sickness. Combined findings from the third and fourth experiments suggest that 0.2 Hz fore-and-aft oscillation causes greater sickness than 0.2 Hz pitch oscillation at each of the three magnitudes studied (assuming that pitch motion can be represented by the gravitational component, gSinθ). A motion sickness model is proposed showing how the factors investigated in this thesis affect the sensed and expected semi-circular canal signals which are assumed to be involved in the causation of motion sickness. The model predicts how sensed and expected signals vary according to the phase between motions, the magnitude, direction and duration of motion, the type of motion and the postural support given to subjects. Explanations of how the model predicts motion sickness based on the findings of this study and previous studies are discussed.
Supervisor: Griffin, Michael Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.561466  DOI: Not available
Keywords: QP Physiology ; BF Psychology ; TL Motor vehicles. Aeronautics. Astronautics
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