An Ecological Critique of the Sensory Conflict Theory of Motion Sickness

In this article we present a critique of the sensory conflict theory of motion sickness. We discuss three forms of sensory conflict that are believed to exist: input conflict, output conflict, and expectancy violation. We argue that any concept of sensory conflict necessarily entails the violation of internal expectations and, hence, that the three forms of conflict are logically identical. In the motion sickness literature, it is implicit that the expected pattern is one in which the inputs of the visual, vestibular, and somatosensory systems are redundant. We argue that an expectation of redundancy cannot plausibly result from interaction with the environment. We review data indicating that nonredundant patterns of intermodal stimulation lead to adaptive changes in the control of behavior; this implies that the calculation of nauseogenic conflict must be unrelated to the control of behavior. Moreover, we argue that no single pattern of sensory stimulation, redundant or otherwise, can serve as a reliable standard or expecta- tion for the calculation of sensory conflict. We conclude that there is no principled basis on which the conflict theory can distinguish between nauseogenic and nonnauseogenic situations. It follows that the concept of sensory conflict cannot provide a theoretical explanation for the existence of motion sickness. We review data suggesting an important role for the control of behavior in the etiology of motion sickness. This suggests a new basis for understanding the phenomena of motion sickness.     

An ecological Theory of Motion Sickness and Postural Instability

In this article we present a new theory of motion sickness. In the sensory conflict theory, changes in stimulation of perceptual systems are believed to be responsible for motion sickness. We discuss the fact that these changes in stimulation are not independent of the animal-environment interaction, but are determined by corresponding changes in the constraints operating on the control of action. Thus, provocative situations may be characterized by novel demands on the control of action as well as by novel patterns of stimulation. Our hypothesis is that animals become sick in situations in which they do not possess (or have not yet learned) strategies that are effective for the maintenance of postural stability. We identify a broad range of situations over which the occurrence of motion sickness is related to factors that should influence postural stability. This allows us to establish a logical link between motion sickness and postural stability. Our analysis implies that an understanding of stability should be an important part of the agenda in research on perception and action in general. We suggest that postural instability could be related to the concept of dynamical disease which has been developed in the literature on nonlinear physiological control systems. We conclude with suggestions for research based on the new approach.     

Control of a Virtual Avatar Influences Postural Activity and Motion Sickness

The influence of vehicular control on motion sickness has implications for theories of motion sickness etiology. We asked whether motion sickness susceptibility might also be related to the control of non-vehicular locomotion. Participants were exposed to a console video game that featured ambulatory locomotion of a virtual avatar. In a yoked control design, individuals either played the game (players) or watched another participant's recorded game play (viewers). Viewers were more likely than players to report motion sickness. During exposure to the video game players moved more than viewers, and the movement of players was more predictable or self-similar than the movement of viewers. Coupling of movement within player-viewer pairs was greater for pairs in which the viewer later reported motion sickness than for pairs in which both participants stated that they were not motion sick. The results reveal that motion sickness incidence can be influenced by the control of stimulus motion, in general, and is not limited to control of vehicular motion. We discuss implications of these findings for theories of motion sickness etiology.     

Stance Width Influences Postural Stability and Motion Sickness

We examined the influence of stance width (the distance between the feet) on postural sway and visually induced motion sickness. Stance width influences the magnitude of body sway, and changes in sway precede the subjective symptoms of motion sickness. Thus, manipulation of stance width may influence motion sickness incidence. Participants (healthy young adults) were exposed to complex, low-frequency oscillation of a moving room. Participants stood with their feet 5 cm, 17 cm, or 30 cm apart. During exposure to visual motion, the widest stance (30 cm) was associated with reduced incidence of motion sickness. For all stance widths, motion sickness was preceded by significant changes in motion of the head and torso. The results support the postural instability theory of motion sickness and suggest practical implications for the prevention of motion sickness. Adoption of wider stance may decrease the risk of motion sickness in operational situations.     

Postural Precursors of Postboxing Motion Sickness in a Manual Aiming Task

We asked whether body sway during performance of a visual-manual task would differ between boxers who experienced post-match motion sickness and those who did not. Before and after boxing we measured standing body sway while participants performed a manual precision aiming task. After boxing, participants stated, yes/no, whether they were motion sick; they also reported motion sickness symptoms, and concussion-related symptoms. Seven of thirteen boxers reported motion sickness after boxing. We compared boxers who reported post-boxing motion sickness versus those who did not. Body sway before boxing differed between boxers who reported post-bout motion sickness and those who did not. Immediately after boxing, motion sickness symptoms and concussion-related symptoms were elevated among boxers who stated that they were motion sick. The results suggest that patterns of body sway may be related to individual differences in susceptibility to motion sickness and concussion-like symptoms in adult male boxers, such that objective measurements of body sway might be used to predict susceptibility in individuals.     

Consequence of Self Versus Externally Generated Visual Motion on Postural Regulation

A limiting factor in the use of virtual environments to examine perception and action is that it is dependent on the quality of the interaction. A virtual reality game (first-person viewpoint with moderate difficulty) was used to investigate the link between control and postural regulation. Postural regulation was examined using a motion capture system, and the differences that emerged as a result of the participant being a passive observer versus an active participant were evaluated using a fractal procedure: dispersion analysis. A significant interaction was found between control and health, namely, participants' postural behavior tended to be less uniform when they were sick and when they were in control of the environment. These results lead the authors to suggest that successful interaction with novel environments depends on the ability to find and consistently use appropriate control strategies.     

Interstimulus Intervals and Sensory Modality Modulate the Impact of a Cognitive Task on Postural Control

The present literature not only reveals the use of a wide variety of cognitive tasks but variability in their interaction with postural control. The question then arises, as to, whether postural control is sensitive to specific features of a cognitive task. The present experiment assessed the impact of cognitive tasks with interstimulus intervals (ISI) of varied duration and sensory modality on postural control in young adults. Seventeen participants (23.71 ± 1.99 years old) were instructed to stand on a force platform while concurrently performing cognitive tasks with ISIs of two and 5 s. The tasks were presented both, auditorily and visually. The visual tasks consisted of counting the total occurrence of a single digit. The auditory tasks consisted of counting the total occurrence of a single letter. Performing the cognitive tasks with an ISI of 2 s resulted only in an increase in the anteroposterior mean power frequency. Presenting the tasks visually also significantly reduced area of 95% confidence ellipse and AP and mediolateral sway variability. These results may suggest that ISIs can modify postural performance by altering the allocation of attentional focus. Also, presenting tasks using a visual sensory modality appears to yield lower postural sway.     

Hierarchical Error Evaluation: The Role of Medial-Frontal Cortex in Postural Control

Motor error evaluation appears to be a hierarchically organized process subserved by 2 distinct systems: a higher level system within medial-frontal cortex responsible for movement outcome evaluation (high-level error evaluation) and a lower level posterior system(s) responsible for the mediation of within-movement errors (low-level error evaluation). While a growing body of evidence suggests that a reinforcement learning system within medial-frontal cortex plays a crucial role in the evaluation of high-level errors made during discrete reaching movements and continuous motor tracking, the role of this system in postural control is currently unclear. Participants learned a postural control task via a feedback-driven trial-and-error shaping process. In line with previous findings, electroencephalographic recordings revealed that feedback about movement outcomes elicited a feedback error–related negativity: a component of the human event-related brain potential associated with high-level outcome evaluation within medial-frontal cortex. Thus, the data provide evidence that a high-level error-evaluation system within medial-frontal cortex plays a key role in learning to control our body posture.     

Wesleyan University Studies of Motion Sickness: V. Incidence of Sickness at Various Hours of the Day

Small groups lasting eight sessions each and aimed at improving patients' interpersonal problem-solving skills were conducted for a total of 41 hospitalized psychiatric patients. Forty control patients received the same pre and posttests but no training. Twenty-three patients participated in play-reading groups without problem-solving training (placebo condition). Three separate 3 by 2 repeated measures analyses of variance showed that hospitalization alone improved the patients' functioning on the criterion test of problem-solving, but that the problem-solving training groups advanced the improvement significantly. More disturbed patients made only slightly greater gains than less disturbed ones. The hospital stay was significantly shorter for the experimental and the placebo groups than for the control sample.     

Cultural Conflict and the Feminine Role: An Experimental Study

Summary

Levenson's multidimensional I-E Scale was administered to 625 male and female university students and adults in America and Greece. The scores were categorized by sex, country, and employment status (job-holding adults or students) on each of the three control dimensions and then subjected to 2 × 2 × 2 analyses of variance. There were no significant sex main effects for any of the three I-E dimensions, thus calling into question previous cross-cultural findings that women were more external than men. Americans and Greeks did not differ on the Personal Control dimension, but Greeks did believe that they live in a more unpredictable environment than the Americans and also one in which powerful others control their outcomes. The results also indicated that students report having less of a sense of responsibility for their own actions than adults, but the two groups did not differ significantly on the Powerful-others or Chance dimensions. Finally, differences in the patterns of scoring across I-E content areas among subjects suggested the usefulness of utilizing a multidimensional I-E scheme in future cross-cultural personality research.     

情绪冲突控制过程的脑电特征研究

应用Flanker研究范式探讨了正常成人被试在情绪冲突控制过程中的脑电特征.结果发现:干扰刺激的特征主要在P200上得到体现,判断刺激的特征主要在N300上得到体现,干扰刺激与判断刺激的特征体现了个体注意控制的过程.积极情绪和消极情绪在判断过程中发挥着不同的作用,但无论是作为干扰刺激还是作为判断刺激,消极情绪都使任务难度增大,对加工过程造成干扰;积极情绪则不然.     

Influence of Complexity and Coupling of Optic Flow on Visually Induced Motion Sickness

Postural stability is critical for our ability to engage in other behaviors and can be influenced by several factors, including changes in optic flow. In situations where postural stability is degraded for prolonged periods of time, motion sickness commonly results. The current research examined how the complexity of a motion stimulus and the coupling of a motion stimulus to the actions of the participant influenced postural sway and motion sickness. Differences in incidence of motion sickness and postural sway characteristics emerged across conditions. In particular, postural sway of participants who became motion sick was characterized by increases in magnitude and spatial complexity but by a decrease in temporal complexity compared with participants who remained well.     

The Role of Visual Feedback about Motion of the Ground on Postural Sway

Abstract

We asked whether body sway would be influenced by visual information about motion of the ground surface. On a ship at sea, standing participants performed a demanding visual search task or a simple visual inspection task. Display content was stationary relative to the ship or relative to the Earth. Participants faced the ship’s bow or its port side. Performance on the visual search task was representative of terrestrial studies. Body sway was greater during viewing of the Earth Stationary displays than during viewing of the Ship Stationary displays. We discuss possible implications of these results for theoretical and applied issues.     

Effects of the Central Executive on Postural Control

The authors focused on individual working memory (WM) capacity and examined its effect on postural control. Participants were 79 young volunteers split into two groups of low- and high WM span, based on scores from the Reading Span Test. The length of unrest was measured in the following conditions: double-leg standing as a single (D-S) task, single-leg standing as a single (S-S) task, double-leg standing as a dual (D-D) task, and single-leg standing as a dual (S-D) task. Regarding inte-group comparisons, total length was prolonged significantly between the low- and the high-span groups but only on the S-D task. The present results revealed that dual-task interference emerged in the low-span group when in a more unstable posture.     

An Experimental Investigation of Source Confusion in Televised Messages: News Versus Advertisements

The study reported here employed a mixed factorial design to experimentally investigate the effects of message format on memory for the source of information. Political messages were presented in 3 types of formats: conventional political ads, news‐like political ads, and news stories. Memory for the source of information was measured directly after exposure and a week later. The results of the experiment suggest that format and time had a significant effect on memory for the source. Subjects identified the source of information with about the same level of accuracy across formats right after exposure. A week later, subjects were significantly more inept at attributing information contained in news‐like ads to its source than doing so for conventional ads and news stories. At that point, information presented in news‐like ads was incorrectly attributed to news about 70% of the time.     

Sensory and Postural input in the Occurrence of a Gender Difference in Orienting Liquid Surfaces

The Psychological Record - In the water-level task, both spatial skill and physical knowledge contribute to representing the surface of a liquid as horizontal irrespective of the container’s...     

Explaining Normative Versus Nonnormative Action: The Role of Implicit Theories

The current research investigates what motivates people to engage in normative versus nonnormative action. Prior research has shown that different emotions lead to different types of action. We argue that these differing emotions are determined by a more basic characteristic, namely, implicit theories about whether groups and the world in general can change. We hypothesized that incremental theories (beliefs that groups/the world can change) would predict normative action, and entity theories (beliefs that groups/the world cannot change) as well as group identification would predict nonnormative action. We conducted a pilot in the context of protests against a government plan to relocate Bedouin villages in Israel and a main study during the Israeli social protests of the middle class. Results revealed three distinct pathways to collective action. First, incremental theories about the world predicted hope, which predicted normative action. Second, incremental theories about groups and group identification predicted anger, which also predicted normative collective action. Lastly, entity theories about groups predicted nonnormative collective action through hatred, but only for participants who were highly identified with the group. In sum, people who believed in the possibility of change supported normative action, whereas those who believed change was not possible supported nonnormative action.     

Control of Equilibrium Position and Stiffness Through Postural Modules

If muscles are viewed as spring-like torque generators, then the integral of torque with respect to joint angle is the potential energy of that muscle. An energy function for the musculoskeletal system can be defined by summing the energy contribution of each muscle and the potential energy stored in the limb. Any local minimum in this energy landscape is a possible equilibrium position for the limb. The gradient of this function with respect to joint angles is a torque field, and the task of postural control is to find a set of muscle activations to produce a desired field. We consider one technique by which this approximation may be achieved: A postural module is defined as a synergy of muscles that produce a class of torque functions that converge at a constant equilibrium position, but whose stiffness at this position varies as a function of activation of the postural module. For a single-joint system, we show that through control of two such modules it is possible to produce any stiffness at any desired equilibrium position. To extend this scheme to a multijoint system, we initially derive the mechanical constraints on the shape of the restoring force field when a multijoint limb is displaced from equilibrium. Next, we consider voluntary control of the force field when the human arm is displaced from equilibrium: Mussa-Ivaldi, Hogan, and Bizzi (1985) have suggested that subjects are unable to voluntarily change the shape and orientation of the field, although they can readily scale it. This suggests existence of a limitation on the independent recruitment of arm muscles. We show, through simulation, that the inability to voluntarily control the shape and orientation of the restoring force field can be attributed to an organization of postural modules that act as local stiffness controllers. We propose that through coactivation, postural modules coarsely encode the work space and serve as an intermediate control system in the motor control hierarchy.