Recent Publications

We investigated relations between experience driving physical automobiles and motion sickness during the driving of virtual automobiles. Middle-aged individuals drove a virtual automobile in a driving video game. Drivers were individuals who had possessed a driver's license for approximately 30 years, and who drove regularly, while non-drivers were individuals who had never held a driver's license, or who had not driven for more than 15 years. During virtual driving, we monitored movement of the...

CONCLUSIONS: The results are consistent with the postural instability theory of motion sickness, and help to illuminate relationships between the control of physical and virtual vehicles.Chang C-H, Chen F-C, Kung W-C, Stoffregen TA. Effects of physical driving experience on body movement and motion sickness during virtual driving. Aerosp Med Hum Perform. 2017; 88(11):985-992.

Virtual environments such as those used in video games and driving/flight simulators are used for entertainment and training, but are often associated with visually induced motion sickness (VIMS). In this study, we asked whether passive restraint of the head and torso could reduce VIMS in younger and older adults. Twenty-one younger (18-35 years) and 16 older (65 + years) healthy adults engaged in a simulated driving task using a console video game while seated. On different days, participants...

Affordances are available behaviors that emerge out of relations between properties of animals and properties of their environment. Affordances are nested within one another. One way to conceptualize this nesting is through a mean-ends hierarchy. Previous research has shown that perceivers are sensitive to hierarchical means-ends relationships when perceiving affordances for their own actions. Affordances are also nested in a social context. We investigated perception of hierarchical mean-ends...

On land, the spatial magnitude of postural sway (i.e., the amount of sway) tends to be greater when participants look at the horizon than when they look at nearby targets. By contrast, on ships at sea, the spatial magnitude of postural sway in young adults has been greater when looking at nearby targets and less when looking at the horizon. Healthy aging is associated with changes in the movement patterns of the standing body sway, and these changes typically are interpreted in terms of...

Anecdotal reports suggest that motion sickness may occur among users of contemporary, consumer-oriented head-mounted display systems and that women may be at greater risk. We evaluated the nauseogenic properties of one such system, the Oculus Rift. The head-mounted unit included motion sensors that were sensitive to users' head movements, such that head movements could be used as control inputs to the device. In two experiments, seated participants played one of two virtual reality games for up...

Motion of the surface of the sea (waves, and swell) causes oscillatory motion of ships at sea. Generally, ships are longer than they are wide. One consequence of this structural difference is that oscillatory ship motion typically will be greater in roll (i.e., the ship rolling from side to side) than in pitch (i.e., the bow and stern rising and falling). For persons on ships at sea, affordances for walking on the open deck should be differentially influenced by ship motion in roll and pitch....

In studying the perception of affordances, researchers have typically identified a single affordance and designed experiments to evaluate the perception of that affordance. Yet in daily life, multiple affordances always exist. One consequence of this is that there may be higher order, means-ends relations between different affordances. In 4 experiments, we created situations in which lower order, subordinate affordances could affect the realization of higher order, superordinate affordances, and...

Research on affordances typically has focused on the identification and perception of a single affordance. However, in daily life, multiple affordances are available. We investigated potential hierarchical relations among affordances of tools in two experiments. In Experiment 1, participants assembled a tool consisting of an L-shaped object and attached masses so as to perform a particular behavior on a target object-tipping over or sliding it-located at a particular distance from the...

The spatial magnitude of standing body sway is greater during viewing of more distant targets and reduced when viewing nearby targets. Classical interpretations of this effect are based on the projective geometry of changes in visual stimulation that are brought about by body sway. Such explanations do not motivate predictions about the temporal dynamics of body sway. We asked whether the distance of visible targets would affect both the spatial magnitude and the multifractality of standing body...

We exposed standing men and women to motion relative to the illuminated environment in a moving room. During room motion, we measured the kinematics of standing body sway. Participants were instructed to discontinue immediately if they experienced any symptoms of motion sickness, however mild. For this reason, our analysis of body sway included only movement before the onset of motion sickness. We analyzed the spatial magnitude of postural sway in terms of the positional variability and mean...

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Motion sickness is more common among women than among men. Previous research has shown that standing body sway differs between women and men. In addition, research has shown that postural sway differs between individuals who experience visually induced motion sickness and those who do not and that those differences exist before exposure to visual motion stimuli. We asked whether sex differences in postural sway would be related to sex differences in the incidence of visually induced motion...

CONCLUSIONS: Motion sickness induced using linear visual oscillatory stimuli exhibited sex differences greater than those that have been reported in field studies. Sex differences in motion sickness may vary as a function of the type of motion stimulation (linear versus angular).

CONCLUSIONS: We obtained direct evidence that ship motions in roll and pitch differentially affect the timing of stepping patterns in human gait. This novel finding motivates new research on quantitative parameters of gait at sea.

Body movement influences the structure of multiple forms of ambient energy, including optics and gravito-inertial force. Some researchers have argued that egocentric distance is derived from inferential integration of visual and non-visual stimulation. We suggest that accurate information about egocentric distance exists in perceptual stimulation as higher-order patterns that extend across optics and inertia. We formalize a pattern that specifies the egocentric distance of a stationary object...

This study investigated the effects of dementia on standing postural adaptation during performance of a visual search task. We recruited 16 older adults with dementia and 15 without dementia. Postural sway was assessed by recording medial-lateral (ML) and anterior-posterior (AP) center-of-pressure when standing with and without a visual search task; i.e., counting target letter frequency within a block of displayed randomized letters. ML sway variability was significantly higher in those with...

On land, body sway during stance becomes coupled with imposed oscillations of the illuminated environment or of the support surface. This coupling appears to have the function of stabilizing the body relative to the illuminated or inertial environment. In previous research, the stimulus has been limited to motion in a single axis. Little is known about our ability to couple postural activity with complex, multi-axis oscillations. On a ship at sea, we evaluated postural activity using measures of...

BACKGROUND: Developmental coordination disorder (DCD) is a diagnosis for children who present with movement difficulties, but are of normal intelligence without neurological deficits. Previous studies have demonstrated that children with DCD exhibit perceptual deficits and lower cognition performance. To date, their autonomic nervous system (ANS) responses during tasks requiring cognitive and perceptual effort have not been compared to typically developing children (TDC).

The control of standing body posture is affected by mechanical perturbations, such as motion of the support surface. Postural activity also is responsive to subtle social factors: When 2 people interact there is spontaneous interpersonal coordination of their movements. We asked whether interpersonal postural coordination based on visual contact would be robust in the presence of mechanical perturbations that characterize sea travel. During an ocean voyage, pairs of participants stood facing...