Knowing what's coming: Anticipatory audio cues can mitigate motion sickness

Being able to anticipate upcoming motion is known to potentially mitigate sickness resulting from provocative motion. We investigated whether auditory cues could increase anticipation and subsequently reduce motion sickness. Participants (N = 20) were exposed on a sled on a rail track to two 15-min conditions. Both were identical in terms of motion, being composed of the same repeated 9 m fore-aft displacements, with a semi-random timing of pauses and direction. The auditory cues were either 1) informative on the timing and direction of the upcoming motion, or 2) non-informative. Illness ratings were recorded at 1-min intervals using a 11-point scale. After exposure, average illness ratings were significantly lower for the condition that contained informative auditory cues, as compared to the condition without informative cues. This knowledge, i.e. that auditory signals can improve anticipation to motion, could be of importance in reducing carsickness in domains such as that of autonomous vehicles

An international survey on the incidence and modulating factors of carsickness

About two in three people have experienced carsickness at some point in their life (Reason & Brand, 1975). Little is known about current numbers of sufferers, cultural differences, or which modulating factors are being perceived as most relevant. Therefore, given a global increase of interest in carsickness driven by the development of automated vehicles, this survey intended to assess the status quo of carsickness in different parts of the world. We conducted an online survey with N = 4,479 participants in Brazil, China, Germany, UK and USA. 46% of participants indicated they had experienced some degree of carsickness in the past five years as a passenger in a car. When including childhood experiences, this rate increased to 59%, comparable to the 1975 findings by Reason and Brand. The highest and lowest incidence of carsickness was reported in China and Germany, respectively. In all countries, men and older participants reported a lower incidence of carsickness as compared to females and younger participants. The main modulating factors were found to be driving dynamics, visual activities, and low air quality. This study showed that carsickness still affects about 2/3 of passengers and discusses how its occurrence relates to in-transit activities and other modes of transport. The research provides a sound basis to further study how carsickness develops and to investigate countermeasures to potentially reduce it

Knowing what's coming: Unpredictable motion causes more motion sickness

This study explores the role of anticipation in motion sickness. We compared three conditions varying in motion predictability and assessed the effect of anticipation on subsequent illness ratings using a within-subjects design. Anticipation is thought to play a role in motion sickness by reducing the discrepancy between sensed and expected sensory information. However, both the exact role and potential magnitude of anticipation on motion sickness are unknown. Participants ( = 17) were exposed to three 15-min conditions consisting of repeated fore-aft motion on a sled on a 40-m rail (1) at constant intervals and consistent motion direction, (2) at constant intervals but varied motion direction, and (3) at varied intervals but consistent motion direction. Conditions were otherwise identical in motion intensity and displacement, as they were composed of the same repetitions of identical blocks of motion. Illness ratings were recorded at 1-min intervals using an 11-point motion sickness scale. Average illness ratings after exposure were significantly lower for the predictable condition, compared with both the directionally unpredictable condition and the temporally unpredictable condition. Unpredictable motion is significantly more provocative compared with predictable motion. Findings suggest motion sickness results from a discrepancy between sensed and expected motion, rather than from unpreparedness to motion. This study underlines the importance of an individual's anticipation to motion in motion sickness. Furthermore, this knowledge could be used in domains such as that of autonomous vehicles to reduce carsickness

Vection does not necessitate visually induced motion sickness

Vection, i.e. a visually induced illusory sense of self-motion, is assumed to play an essential role in visually induced motion sickness (VIMS). However, its precise role is unknown. Following the sensory conflict theory, a constant state of vection is not expected to lead to a visual-vestibular conflict whereas variability in vection, i.e. change in vection strength over time, would. In this study we investigated whether variability in vection rather than vection caused VIMS in participants exposed to constant optic flow using a head-mounted display. Strongest possible vection (i.e. 100% on a 0–100% scale) was reported by 16 out of 18 participants at some point during the experiment, with a total average vection score over the experiment of 58.6%. Initial motion sickness symptoms were reported by 15 out of 18 participants, although only averaging 1.78 on an 11-point scale. Neither average vection strength nor variability in vection were significantly correlated with motion sickness. Relating our findings to the literature, we argue that vection should be understood not as a direct cause of VIMS, but as a perceptual state still depending on other visual factors before VIMS occurs. Vection by itself, even if it is experienced strongly, does not necessitate VIMS

In-car speed estimations with real, virtual, and no view

Car handling, and hence, safety, is affected by the way we estimate speed. Speed, however, is often underestimated in degraded visual environments, including virtual environments such as driving simulators. In simulators the visual and physical motion are typically incongruent as limited by quality and amplitude, respectively, which may cause a negative transfer of training. To improve the (training) quality of simulators and make them feel more real, it would be helpful to fill a knowledge gap on in-car speed perception as affected by real and virtual views, within a single group of subjects. We did so by testing whether estimations of speed in terms of km/h could be a valid metric for that purpose. We therefore exposed 17 subjects, seated as passengers in the front of a car on a straight road to four experimental conditions: (1) driving with a real out-the-window view, (2) driving with a live video view, (3) standing still watching pre-recorded video's, and (4) driving with eyes closed. Field-of-view was made equal in all conditions. Speeds tested ranged between 20 and 60 km/h. On average, speed was estimated 5 km/h less than actual, while we did not find a statistically significant difference between the four conditions tested. These results seem to contradict previous observations on motion perception, in particular in simulators, that have been ascribed to the quality of the visuals used. This finding may yet be explained by the assumption that speed estimations in terms of km/h are dominated by (conscious) cognitive processes, while visual-vestibular coherence between visual and physical motion, is dominated by (unconscious) sensorial driven perceptual processes. This disqualifies perceived speed as a valid metric for studying motion perception related to the optimisation of simulators