Abstract
High levels of vehicle automation are expected to increase the risk of motion sickness, which is a major detriment to driving comfort. The exact relation between motion sickness and discomfort is a matter of debate, with recent studies suggesting a relief of discomfort at the onset of nausea. In this study, we investigate whether discomfort increases monotonously with motion sickness and how the relation can best be characterized in a semantic experiment (Experiment 1) and a motion sickness experiment (Experiment 2). In Experiment 1, 15 participants performed pairwise comparisons on the subjective discomfort associated with each item on the popular MIsery SCale (MISC) of motion sickness. In Experiment 2, 17 participants rated motion sickness using the MISC during exposures to four sustained motion stimuli, and provided (1) numerical magnitude estimates of the discomfort experienced for each level of the MISC, and (2) verbal magnitude estimates with seven qualifiers, ranging between feeling ‘excellent’ and ‘terrible’. The data of Experiment 1 show that the items of the MISC are ranked in order of appearance, with the exception of 5 (‘severe dizziness, warmth, headache, stomach awareness, and sweating’) and 6 (‘slight nausea’), which are ranked in opposite order. However, in Experiment 2, we find that discomfort associated with each level of the MISC, as it was used to express motion sickness during exposure to a sickening stimulus, increases monotonously; following a power law with an exponent of 1.206. While the results of Experiment 1 replicate the non-linearity found in recent studies, the results of Experiment 2 suggest that the non-linearity is due to the semantic nature of Experiment 1, and that there is a positive monotonous relation between MISC and discomfort in practice. These results support the suitability of MISC to assess motion sickness.
Highlights
It is expected that the introduction of automated vehicles will provide major benefits in terms of safety, utility, and comfort to passengers as well as having beneficial effects on the environment through increased driving efficiency
As per anecdotal data obtained during debriefing, this was due to responses of a few individuals who associated vomiting with a relief of motion sickness symptoms
The verbal qualifiers indicate that individuals tend to agree on feeling ‘terrible’ at a MIsery SCale (MISC) of 6; feeling ‘so–so’ occurs between MISC scores of 1 and 3, and individuals differ with respect to the baseline level of comfort experienced, such that people tend to start out feeling ‘good’, rather than ‘excellent’
Summary
It is expected that the introduction of automated vehicles will provide major benefits in terms of safety, utility, and comfort to passengers as well as having beneficial effects on the environment through increased driving efficiency. To prevent and mitigate this issue as much as possible, it is necessary to understand the aetiology of motion sickness and determine its relation to discomfort. This in turn requires reliable tools to measure these states experimentally. Motion sickness may be quantified using physiological measures or subjective rating scales. Physiological measures, such as Electro-GastroGraphy (EGG; e.g., Gruden et al 2021) or the Galvanic Skin Response (GSR; e.g., McClure et al 1971; Cowings et al 1986; Irmak et al 2020)
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