Motion Sickness Literature Search

ARMY RESEARCH LABORATORY

Motion Sickness Literature Search

Patricia M. Burcham

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ARL-MR-504 MAY 2002

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Army Research Laboratory Aberdeen Proving Ground, MD 21005-5425

ARL-MR-504 May 2002


Patricia M. Burcham Human Research & Engineering Directorate


A review of the literature about motion-induced cognitive and perceptual decrements and about motion sickness was conducted to identify screening methods and mitigation techniques and to gain estimates of the portion of population affected. Screening and mitigation techniques that show promise for indirect driving will be evaluated in imminent laboratory and field experiments.

Contents

1. Background 1

2. Findings 2 2.1 General 2 2.2 Visually Induced 7 2.3 Coriolis Induced 9 2.4 Immersive Virtual Reality 12 2.5 Low Frequency Linear Oscillation 13 2.6 Simulator Sickness 15 2.7 Seasickness 15 2.8 Ground Vehicle Sickness 16 2.9 Air Sickness 20

3. Discussion 21

4. Recommendations and Conclusions 24

References 27

Appendix A. Summary Chart 31

Distribution List 49

Report Documentation Page 51

Figures 1. Median Symptoms Over Time 19 2. Mean Symptoms Over Time 20

Table 1. Sensory Rearrangements Known to Produce Motion Sickness 3

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IV

MOTION SICKNESS LITERATURE SEARCH

1. Background

Motion sickness is a syndrome precipitated by different forms of travel, amusement park rides, and other unusual forms of motion. There are generally three classes of symptoms that can be distinguished. The first class consists of a disruption in perceptual and sensorimotor activities involving the vestibular system, such as disorientation, disequilibrium, and inappropriate vestibulo- ocular or vestibulo-spinal reflexes. The second group also appears to have a perceptual origin and consists of many autonomic symptoms such as pallor, drowsiness, salivation, sweating, nausea, and vomiting. The third set of symptoms is referred to as the "sopite syndrome" which includes symptoms such as mood changes, lethargy, and sleep. The onset of motion sickness symptoms is known to cause performance decrements (Yardley, 1992; Lawson & Mead, 1998).

To equip the Army with a rapidly deployable force, combat vehicles need to be smaller, lighter, survivable, and more mobile. Future combat vehicles require crew stations to be positioned deep within the vehicle hull. Vision blocks and sights will be replaced with cameras and displays. Thus, driving will be conducted with indirect vision that can lead to motion sickness because of display resolution, field of view (FOV), and system lag problems. In addition, vehicle control will be exercised through controls and displays without a direct view of the outside world. Because the Future Combat Systems program emphasizes moving operations, any additional perceptual and cognitive load placed on the soldier may result in unacceptable performance decrements. As a result, the Human Research and Engineering Directorate of the U.S. Army Research Laboratory (ARL) has identified a need to investigate and identify the causal effects of motion sickness as related to indirect driving and the use of displays in combat vehicles. In preparation for experimental research, ARL completed a literature search to investigate possible prevention methods, the percentage of population affected, and possible subject screening methods. The results yielded the identification of susceptibility factors, motion sickness theories, and motion sickness history questionnaires that may be used for validation purposes and may provide a means to screen study participants. No research was conducted on motion sickness associated with indirect driving. Factors influencing susceptibility include sex, age, exposure history, receptivity, adaptability, and personality characteristics. ARL's research will be tailored to validate screening methods and to apply previous successful efforts in reducing motion sickness to current systems and development.

2. Findings

2.1 General

2.1.1 Reason, 1978

Reason reviewed some important theoretical and practical considerations related to motion sickness. Sensory rearrangement theory is briefly outlined. Behavioral measures to minimize the risk of motion sickness, quantitative studies of vertical periodic motion, factors influencing susceptibility to motion sickness (sex, age, exposure history, receptivity and adaptability, and personality characteristics), and recommendations of the most effective use of anti-motion sickness drugs are discussed. Based on previous research, a variety of drugs and drug combinations was shown to offer some protection against motion sickness, but none are entirely effective in all conditions.

2.1.1.1 Sensory Rearrangement

Sensory rearrangement, a predominant theory, was coined to describe the main ingredient of experimental situations in which information reaching one set of receptors is systematically distorted to render it incompatible with that reaching functionally related receptors. The spatial senses (eyes, vestibular system, proprioceptive receptors in joints, tendons, and muscles) function in harmony to convey perfectly correlated information. This delicate harmony can be disrupted when persons work in an environment where these senses conflict. When we allow ourselves to be transported by mobile device or to be moved within an unusual force environment, this delicate harmony is disrupted. Incongruity among the normal channels of information is produced and a mismatch occurs between the pattern of spatial input of what is perceived and what is expected, based on previous experience with the natural environment. Two classes of sensory rearrangement include visual-inertia rearrangement (inertial includes both the vestibular and non-vestibular proprioceptors) and canal-otolith rearrangements (when vision is absent). The synergistic relationship between visual and inertial senses and between the canal and otolith receptors can be disturbed in three ways1.

Type 1 - When A and B simultaneously signal contradictory or uncorrelated information.

Type 2 - When A responds in the absence of an expected corroborating signal from B.

Note. A and B represent positions of these normally correlated receptor systems; specifically, A represents visual or canal while B represents inertial or otolith, respectively.

Type 3 - When B responds in the absence of an expected corroborating signal from A.

Therefore, six situations in which motion sickness may be expected to occur if the theory is true can be derived from the two classes of sensory rearrangement and three conflict types (see Table 1).

Table 1. Sensory Rearrangements Known to Produce Motion Sickness

Type of motion cue mismatch Visual (A) - Inertial (B) Canal (A) - Otolith (B)

Type I: AandB simultaneously signal contradictory information

TypelE: A responds without expected B signal

Type III: B responds without expected A signal

1. Seated so that the external view is from a side or rear window of a moving vehicle

2. Moving the head while wearing an optical device that distorts the visual field.

1. Viewing a cinerama-type motion picture while in a moving vehicle.

2. Operating a fixed base vehicle simulator with a dynamic visual display (simulator sickness).

1. Trying to read a map or book while in a moving vehicle.

2. Riding in an enclosed vehicle (no external visual reference).

1. Tilting the head about an axis other than the axis of spinning while riding on a rotating platform (cross- coupled or Coriolis sickness).

2. Making quick head movements while in weightless flight (space sickness).

1. Irrigating the outer ear with water that is hotter or colder than blood temperature (caloric stimulation).

2. Pressure vertigo because of ambient pressure changes.

1. Low frequency (<0.5 Hz) linear oscillation.

2. Rotation about a non- vertical or earth-horizontal axis.

There are at least two important implications for the practical management of motion sickness. First, the applied researcher is directed to assess the nauseogenic potential of a particular vehicle design or seating configuration. The sources of motion information available to the passenger and how these sources are most likely to be in conflict need to be determined. The researcher then needs to consider whether an existing conflict could be eliminated or reduced by repositioning the passengers' seats or providing a more adequate external visual reference.

When possible, seats should be designed to give positive head restraint, since limiting independent head wobbling is known to be highly effective in reducing the incidence of motion sickness. There is also considerable evidence that adopting the supine position (lying on the back with face upward) reduces the risk of symptoms. Second, the passenger has considerable behavioral control over his or her own susceptibility. Canal-otolith conflicts can be minimized by keeping the head as still as possible or by adopting the supine position when practical. Visual-inertial conflicts can be minimized by maintaining a clear view of the road ahead, focusing on the horizon or on any visible landfall. When a visual-inertial conflict is inevitable (e.g., when sitting in a backward or sideways facing seat or being below decks or in any enclosed vehicle), it often helps to close the eyes. If this is impractical, some benefit may be gained by wearing an optical device that occludes the peripheral visual field, leaving the central area unobscured. Thick spectacle frames may even confer some advantage. There is considerable evidence that the central FOV is minimally involved in maintaining spatial orientation.

2.1.1.2 Quantitative Studies of Vertical Periodic Motion

Wave frequency is the critical factor in triggering mechanisms responsible for motion sickness in vertical periodic motion, and the greatest responsivity of these mechanisms is the frequency region of 0.2 Hz. Sickness incidence diminishes with increasing frequency and is nearly nonexistent above 0.6 Hz. Sickness incidence increases as a monotonic function of acceleration level over a range from 0.03 g to 0.04 g. As a result, caution has been given against the engineering strategy of "smoothing" the ride characteristics by reducing the high-frequency motion (over 0.5 Hz) at the expense of increasing energy in the lower frequency bands, since even moderate accelerations at frequencies in the region of 0.2 Hz produce a very high risk of motion sickness.

2.1.1.3 Motion Sickness Susceptibility Factors

Factors influencing susceptibility include sex (women are more susceptible than men), age (peaks at age 12, then declines), exposure history (experiential factors may contribute to gradual diminution of susceptibility), receptivity (refers to the characteristic way the central nervous system transduces or codes stimulus energy), adaptability (refers to the rate at which an individual adjusts to sensory rearrangement), and personality characteristics (positive correlation between neuroticism and motion sickness susceptibility; susceptible persons tended to have a more emotional or autonomic nervous system response to stress).

2.1.2 Brand and Reason, 1975

Brand and Reason discuss the weaknesses of the over-stimulation and otolith theories while supporting the "sensory conflict" theory and the neural mismatch hypothesis of motion sickness. The central thesis is that the conflict theory offers the most plausible basis for the identification of essential common features of

different situations that provoke symptoms. All motion sickness-provoking situations involve sensory rearrangement whereby motion signals transmitted by the eyes, vestibular system, and nonvestibular proprioceptors are mismatched with one another as well as what is expected because of prior experience. The vestibular receptors are always implicated directly or indirectly in these conflicts as in visually induced sickness. The input to the vestibular receptors is artificially distorted, rendering them incompatible with the eyes, one another, or both.

Most sickness-provoking sensory conflicts fall under two general headings. One is visual-inertial rearrangements in which the conflict lies between two sense modalities2, and the other is canal-otolith rearrangements in which the conflict is within one modality, between the two vestibular receptor systems.

When an individual is denied an external visual reference (such as passive vehicular motion in which the passenger does not have a clear view of the external environment), motion sickness susceptibility may be reduced by the passenger shutting his eyes or having an artificial horizon provided.

Brand and Reason also discuss "protective adaptation," which is a diminishing and eventual disappearance of motion sickness signs and symptoms in most individuals after prolonged exposure to a provocative stimulus.

Motion sickness most likely first appeared as a result of man's first attempt to improve his mobility through the construction of a boat.

In 1881, Irwin remarked that seasickness was prompted by a "discord between the immediate or true visual impressions and a certain visual habit or visual sense of the fitness or order of things..." This was coined the "visual vertigo" theory, which is similar to sensory conflict.

Motion sickness was a problem of "considerable military significance" during World War II. Motion sickness resulted in serious efficiency degradation because troops were not accustomed to being transported by land, sea, and air.

Wave motion research directed by Wendt at the Wesleyan University and University of Rochester revealed that sickness incidence peaked in a frequency range between 0.25 and 0.33 Hz.

Brand and Reason discuss the fact that similar findings by investigators using swings with a frequency swing of 0.25 Hz were effective in producing sickness. Faster or slower swinging rates resulted in lower incidence of sickness.

2In which "inertial" refers to both the vestibular and nonvestibular proprioceptors

Benson (1973) obtained a clear negative correlation between sickness incidence and the frequency of oscillation over a range of frequencies investigated (0.22 to 0.59 Hz).

The consistent finding in vertical oscillation studies is that 0.25 Hz is most effective in producing sickness, while frequencies of 0.55 Hz or greater generally elicit little or no sickness. Experimental evidence shows that within a frequency range of 0.1 to 1.0 Hz, there is a change in phase angle between the stimulus and the response from otolithically driven cells in the vestibular nuclei, while between 1.0 and 2.0 Hz, the phase angle is relatively stable.

In 1942, the National Research Council of Canada studied the cause, incidence, and control of motion sickness. Canadian wartime investigators made some of the most significant contributions toward motion sickness prevention and understanding. The "roll-pitch rocker" was used in these studies to simulate vehicle motion (Morton et al., 1947). Later, the two- and four-pole swings became the primary research tools (Manning, 1943; Manning & Stewart, 1949). Johnson and his colleagues demonstrated that mechanical head restraint is effective in reducing the incidence of sickness aboard various types of transport. Canadian researchers also conducted drug studies. The principal result was the Royal Canadian Navy seasickness remedy—a combination of hyoscyamine, hyoscine, and niacin. The United States armed services later adopted this preventive medication.

Russian investigators exposed their trainee aviators to vestibular training (a full gamut of accelerative stimuli before flight). It was designed to prevent motion sickness by promoting "statokinetic stability." This reflects a person's ability to regain balance after being subjected to rapid rotation that artificially disturbs the sense of orientation.

The most important wartime discoveries included understanding the functioning of the vestibular system in producing symptoms, the efficacy of hyoscine as a preventive, susceptibility assessment techniques, protective adaptation mechanisms, quantitative data about effective characteristics of motion stimulus, and important qualitative information about the effects of head position and external visual reference on motion sickness susceptibility.

Brand and Reason further discuss three types of conflict within each of the two broad rearrangement categories. There are six distinct kinds of sensory conflict in which motion sickness can occur.

Graybiel (1965) concluded that motion sickness is a "vestibular sickness" after 10 years of study of individuals whose labyrinths had been destroyed. These

individuals never experienced motion sickness symptoms during exposure to a wide variety of provocative situations.

There are few investigators today who would claim that the semicircular canals are exclusively involved in the cause of motion sickness. The same holds true for the "otolith-only" viewpoint.

The supine position is beneficial in reducing motion sickness symptoms and can be attributed to the otoliths being less responsive to vertically acting linear accelerations. The supine position offers a considerable degree of head restraint.

Brand and Reason discuss motion sickness and performance, motion sickness susceptibility factors, Coriolis techniques, and questionnaires to reveal an individual's sickness frequency and severity of symptoms.

2.1.3 Yardley,1992

This research examined the role of activity and perceptual learning in motion sickness through a survey of two kinds of research. The first is concerned with perception of orientation and self-motion during the conditions of "sensory conflict," which are thought to cause motion sickness. The second consists of investigations into prediction and prevention of motion sickness. The inconclusive results of both kinds of motion sickness research have stemmed from a common neglect to examine the role played by active perceptual strategies, exploration, and voluntary movement in reactions to unusual perceptual environments. The studies reviewed in this paper have used unrepresentative perceptual conditions and have controlled or ignored the voluntary activities and perceptual strategies employed by their subjects. Therefore, these studies have excluded the very factors most likely to influence responses to nauseogenic conditions. A complete re-evaluation of motion sickness seems overdue. It is suggested that research addressing susceptibility and resistance to environments provoking illness adopt a fresh approach. More specifically, research should be concerned with informative structures that can only be defined in relation to the activities of the perceiver.

2.2 Visually Induced

2.2.1 Dolezal, Connon, and O'Neal, 1985

In this study with 15 subjects, the visual environment was manipulated by prismatically reversing the "up-down" FOV, which was preceded by a no-prism baseline condition. The purpose of this procedure was to determine if unfamiliar and unexpected optical information can lead to motion sickness. Vestibular stimulation was held constant. Subjects were required to repeat six visually guided fine motor coordination tasks that followed an increasing order of difficulty for all subjects. The first three tasks were standardized Bailey Infant Scale of Mental Development Items. First, subjects were asked to drop 10 small

1/2-inch cubes singly into a small hole in the center of a container after removing the top, emptying the cubes, and replacing the top. Second, subjects were asked to remove six pegs from a pegboard, place the pegs on the side of the pegboard farthest from him, and to replace them. Third, subjects were asked to build a tower of eight, 1-1/4-inch cubes from a pool of 12 cubes symmetrically arranged in a 5-inch by 6-1/2-inch by 2-1/2-inch deep box. Subjects had to place the eight blocks on the table first before they began building the tower. Fourth, subjects were required to exchange one AA size battery in a 4-1/2-inch by 2-1/2-inch calculator for another. Fifth, subjects were shown a standard 13-inch by 13-inch checker board fully set up for play and were asked to replace the plastic pieces exactly. The experimenter then placed the game pieces by handful into a 5-1/4-inch by 6-3/4-inch by 2-1/2-inch deep box from which the subjects were required to retrieve them. Sixth, subjects were asked to place, from a tray, 2-1/2-inch long plastic pegs into their respective holes in a "Score 4," 8-inch by 8-inch game board and then to place one plastic bead on each of the pegs. Times were recorded. Additionally, behavioral tests were conducted, which included perceptual tasks, equilibrium tests, fine and gross motor coordination tests, and motion sickness ratings. The short session was 65 to 75 minutes, and the long session was 85 to 100 minutes.

The following symptoms were observed: dizziness and queasiness, especially during head movements; poor balance when participants stood; unsteady equilibrium while participants walked; disorientation when participants moved around and during attempted precise eye-hand coordination; and associated autonomic activity including sweating (GSR), muscle tension (EMG), skin surface temperature (EDG), and pulse throughout.

Subjects showed rapid improvement when they performed six visually guided fine motor coordination tasks for a second time. The results demonstrated the prominent role played by unfamiliar and unexpected optical movement information. This experimental paradigm is believed to perceptually pre-adapt personnel to the ill effects visually inherent in disorienting situations.

2.2.2 Dobie, May, Fisher, and Bologna, 1989

Techniques for reducing visually induced motion sickness were examined. Subjects were selected and assigned to one of four groups, based on their responses to a motion sickness questionnaire. One group received 10 sessions of desensitization training (DT) only; a second group received 10 sessions of cognitive therapy (CT) only; a third group received 10 sessions of combined desensitization and cognitive therapy treatment (CG); and a fourth group received no treatment (C). The results indicated that the groups that received cognitive therapy (i.e., CT and CG) exhibited significant increases in tolerance to visually induced motion (VM) when pre-treatment measures were compared to post-treatment measures.

2.2.3 Dobie and May, 1990

The objective was to determine to what extent training tolerance of one motion stimulus would generalize other motion experiences. The three apparati used included a Dichgans and Brandt circular drum with a mirrored ceiling and inner surface lined with 6-inch wide alternating black and white vertical stripes, a rotating chair that tilted ±40° in both the frontal and lateral planes, and a standard video monitor that displayed a white square that expanded from 1° to 9° of visual angle over repeated periods of 800 ms. During post-tests, it was revealed that treatments with the chair and the drum provided specific increases in tolerance of the device used during treatment and that treatment with the chair provided a generalized tolerance of visually induced motion. The results supported the notion of specific and general components in learning to tolerate motion environments.

2.2.4 Tiande and Jingshen, 1991

Findings show that yaw vection, combined with pitch or roll head movements, significantly increased motion sickness, while pitch vection with any type of head movement or head and scene rotation about the same axis significantly reduced motion sickness. When the head was kept stationary, pitch vection was most stressful for motion sickness, followed by roll vection, then yaw vection, although yaw vection was the strongest sensation of self-rotation.

2.3 Coriolis Induced

2.3.1 Woodman and Griffin, 1997

Coriolis stimulation (or cross-coupled stimulation) occurs when the head is rotated about an axis other than the axis of rotation of the body. This will occur, for example, when the head is rotated in pitch while the person sits on a chair and undergoes continuous rotation in yaw (i.e., about a vertical axis).

Coriolis stimulation studies are often conducted with constant speed rotation about an axis close to the head. However, head movement required to cause cross-coupled stimulation tends to take the head away from the center of rotation. At positions other than at the center of rotation, the head will be exposed to gravitational acceleration as well as centripetal acceleration. Therefore, when the head moves, the change in acceleration differs from the acceleration that occurs with the same head movement at the center of rotation. The otoliths will give a response to head pitch through the acceleration caused by the combination of the earth's gravitational field and any centripetal acceleration. If otolith signals influence motion sickness during Coriolis stimulation, a difference in sickness can be expected when head movements are made at the center of rotation (where there is no centripetal acceleration) or away from the center of rotation.

One objective of this experiment was to compare sickness provoked by Coriolis stimulation when the person is seated away from the center of rotation with sickness when the person is seated at the center of rotation.

There were 24 blindfolded participants who were trained to make 30-degree pitch motions of the head every 30 seconds while rotating about a vertical axis at 10 rpm on a turntable at two separate locations: (a) at the center of rotation, and (b) 0.75 m from the center of rotation. Following each head movement, the participants rated their motion sickness. The reported symptoms varied between participants from simply becoming tired to slight dizziness to very nauseous.

It was concluded that precise body location at the center of rotation is not critical during Coriolis stimulation, but the direction of head movement has a large effect on nausea. Participants responded that rotating the head downward (i.e., pitched forward) gave rise to increased motion sickness symptoms more so than did rotating the head upward. It is suggested that there is an influence of somatosensory information on sickness caused by Coriolis stimulation. There were no significant differences between the ratings given by men and women either at the center of rotation or at the radius of rotation.

2.3.2 Cowings and Toscano, 1982; Toscano and Cowings, 1982

Autogenic feedback training (AFT) for motion sickness symptom suppression was the focus of Cowings and Toscano's (1982) research. Twenty-four men were randomly assigned to four groups matched for Coriolis motion sickness susceptibility. Coriolis sickness involves cross-coupled angular acceleration whereby the head is rotated about an axis other than the axis of bodily rotation. These head motions deliver Coriolis accelerative stimulus to the semicircular canals which then give signals that differ from those that occur with this head movement in a stationary environment. The "unexpected" signal from the semicircular canals offers a varied combination of canal, otolith, and somatosensory signals than what is expected from past experience. This is one cause of motion sickness.

Treatment group I (highly susceptible) and treatment group II (moderately susceptible) significantly improved performance in the Coriolis sickness susceptibility index (CSSI) after being taught to control autonomic responses with a training method called autogenic feedback. The highly and moderately susceptible groups were given 2 hours of this training about self-regulation of physiological responses. The article discusses receptivity, a perceptual phenomenon that describes how the central nervous system as a whole codes stimulus intensity. It is believed that a neural mismatch produces a stress-like response of the autonomic nervous system. Delineation between the tonic and phasic properties of a specific biological process (e.g., heart rate) is necessary since these physiological responses are time dependent. Tonic activity is the underlying baseline level that is more stable over a longer period of time. Phasic

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activity is the responses superimposed on the tonic level, which are more unstable and of snorter duration. Tonic and phasic properties of a specific biological process (e.g., heart rate) are also discussed. AFT is an autonomic conditioning procedure. Frequent observations of individuals who are highly- susceptible to motion sickness initially produce larger shifts from baseline in autonomic response levels as a consequence of nauseogenic stimulation, whereas individuals of moderate or low susceptibility exhibited more tightly integrated patterns of activity with changes of smaller magnitude. As an individual learns to diminish autonomic reactivity, the tolerance of motion-sickness-eliciting stimuli increases. It is possible that observed differences in initial susceptibility may be related to the ability of the brain to effectively regulate autonomic reactions to nauseogenic stimuli.

Toscano and Cowings (1982) compared AFT and an alternate cognitive task at reducing motion sickness. AFT involved practicing a series of mental exercises to facilitate control of autonomic activity which, in turn, reduced the tendency for autonomic activity levels to diverge from baseline during stressful conditions that cause motion sickness. The alternate cognitive task involved a probability- monitoring task in which subjects played "blackjack" with verbal information only. Visual and verbal information was provided until the subject could play blackjack with verbal information only. The subject's cards were read to him between head movement instructions. Each subject was asked to keep track of the game, emit verbal responses for "playing the hand," and make head movements as requested via a tape-recorded voice.

Eighteen men were randomly assigned to three groups matched for Coriolis motion sickness susceptibility. Group I was taught to control their autonomic responses. Group II received "sham" training and an alternate cognitive task, and Group III received no treatment. The treatment group received a total of 6 hours of autogenic feedback training in self-regulation of physiological responses. Results showed that Group I could withstand the stress of Coriolis acceleration as much as three times longer after training. There were no changes in Groups II and HI.

2.3.3 Miller and Graybiel, 1970

A standard method for quantifying susceptibility to Coriolis sickness was evaluated. The subject was secured in a Stille rotary chair and blindfolded to eliminate any visual influences. Each subject was required to demonstrate the standardized head movement sequence that provides the Coriolis acceleration during chair rotation. The chair was accelerated in a clockwise or counterclockwise direction until one of several constant velocities was reached. Sequential head movements were continued until a cumulative point score of symptoms totaled 8, the lowest number of points in the severe malaise criterion (M III). Motion sickness signs and symptoms were scored on a tally sheet. When head movements at a constant chair velocity produce vestibular stress that

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exceeds functional vestibular reserve, the average relative stimulus effect of a single head movement can be expressed by factor E. Factor E is linearly related (log/log function) to chair velocity. The CSSI, each individual's score, can be calculated by multiplying the E factor for the revolutions per minute used in the study by the number of head movements (N) required to elicit M III (CSSI = E x N). The result yields a quantitative motion sickness susceptibility to Coriolis acceleration within a single scale of numbers (1 to 100).

2.4 Immersive Virtual Reality

2.4.1 E.C. Regan, NATO Research Study Group 16 Workshop Presentation

This study was conducted to document the frequency of occurrence and severity of negative or unwanted side effects of immersive virtual reality (VR) technology. Apparatus included a Provision 200 VR system, virtual research flight helmet, Polhemus Fastrak tracking system, three-dimensional (3-D) mouse, and standard demonstration software. Subjects were required to complete a malaise rating scale before the immersion, at 5-minute intervals during the 20-minute immersion period, and at 5 and 10 minutes post-immersion. Subjects also completed a standard simulator sickness questionnaire immediately before and after the immersion. The questionnaire consisted of a range of symptoms that invited the subjects to respond to the absence, presence, and (sometimes) severity of the symptoms. Sixty-one percent of subjects reported some symptoms of malaise at some point during the 20-minute immersion period and 10-minute post-immersion period. These symptoms ranged from headaches and eye strain to severe nausea. Five percent of the subjects had to withdraw because their symptoms were severe. Two possible side effects were documented and discussed. The first possible cause is a conflict of senses during VR immersion that results in malaise. The second is technology factors, such as display resolution, which are responsible for some of the symptoms.

Many of the side effects that result from VR immersion are similar to motion sickness symptoms. This article discusses sensory conflict theory and the fundamental signs and symptoms of motion sickness (nausea, pallor, flushing, cold sweating, abdominal discomfort, changes in gastric motility, changes in levels of circulating hormones, and cardiovascular and respiratory changes).

The basis of the sensory conflict, a prevalent theory, is that all conditions that provoke motion sickness are characterized by a situation in which the signals transmitted from the visual system, the vestibular system, and the non-vestibular position senses conflict with each other or with our expectations that are based on previous experience. There are two main conflict categories: either the information from the visual system and the information from the vestibular system are incompatible with each other, or the information from within the vestibular system is incompatible (i.e., canals and otoliths provide incompatible signals).

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Immersive VR can induce sensory conflict when movement is controlled by some form of hand device. It induces a conflict with the visual and vestibular systems; the visual system suggests body movement while the vestibular suggests a more static body position. It would seem plausible that by bringing the visual and vestibular cues more into alignment, side effects would be reduced. One way might be to facilitate more natural methods of moving through virtual environments such as coupling subjects' movements on a treadmill to their movements in the virtual world or interfacing an exercise bike to the VR system. Sensory conflict is unlikely to be the sole causal factor. Some side effects may be attributable to technological factors such as resolution, FOV, and system lag. Low-resolution head-mounted displays (HMDs) are more likely to increase visual system stress than higher resolution devices. The impact of resolution improvements is not clear. It is suggested that visual enhancements may not reduce malaise. Some evidence even suggests increased simulator discomfort with technological advances. It is unclear what effect FOV has on malaise during VR immersion. A wide FOV may create more compelling feelings of vection that may increase malaise, but a narrow FOV may require greater head movements that may also increase malaise.

Literature about simulator sickness suggests that symptoms of malaise increase as system lag increases. Anecdotal evidence suggests that variations in lag, rather than lag by itself, cause malaise. Display update lags may induce a conflict when the time between an action (head movement) and the result (change in visual scene) become discernible. The visual-vestibular conflict arises from discrepancies in time between the physical movement (provides vestibular cues) and the movement of the visual field. Presently, there are few data about minimum discernible lags or acceptable levels of system lag.

2.5 Low Frequency Linear Oscillation

2.5.1 Golding and Kerguelen, 1992; Golding, Markey, and Stott, 1995

Golding and Kerguelen (1992) compared the nauseogenic potential of low frequency linear motion in the "earth-vertical" (sitting upright) versus the "earth-horizontal" (supine) plane, delivered through the same Z-axis of the head and body. Subjects were exposed to linear motion (0.3 Hz, 1.8 ms"2 root mean square) through the same head and body Z-axis in earth-vertical versus horizontal while they performed a continuous visual search task or shut their eyes. The visual search task required each participant to search for a number that was defined by the intersection of a letter (column) and number (row) combination. This combination was given to the participant verbally. The search matrix consisted of 12 columns by 12 rows. The defining letters (A to L) and numbers (1 to 12) were placed in a random order to make the participant scan widely. The matrix was situated 0.6 m from the participant's eyes. Analysis of covariance for sickness rating as covariant of performance, removing any time and subject, vertical or horizontal effects, revealed a small but significant

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relationship between deviation in sickness rating and concurrent deviation in performance (r = -0.21, df 120, 2-tailed p < 0.05). There was correspondence to a reduction in response rate by approximately two responses per minute across the extremes of sickness rating from "feeling OK" to "moderate nausea". Results showed that vertical motion was clearly more provocative than horizontal motion. Performance of the search task was hampered by motion sickness.

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Golding, Markey, and Stott (1995) demonstrated that low frequency linear oscillation through the z-axis of the body was more nauseogenic when it was applied in the vertical direction, with subjects seated upright, than in the horizontal direction, with subjects supine. Results suggest that upright versus supine body posture and stimulation through x-axis versus z-axis together enhance the nauseogenicity of low frequency linear oscillation, and these effects are additive. However, motion direction with respect to gravity vector (horizontal versus vertical) is a less important factor.

A servo-controlled hydraulic platform with a canvas cab that housed a seat and headrest produced vertical motion. A sled carrying a similar enclosed canvas cab that housed a seat and headrest produced horizontal motion. A standard five- point harness with quick release box was used to restrain subjects. A padded rear head support was provided. Otherwise, the head was not restrained. Subjects were enclosed in a canvas cab to eliminate visual and tactile (airflow) cues of motion. Subjects were required to perform a continuous visual search task according to verbal instruction that consisted of searching for a digit in a 12-by-12 matrix. This search task acted to control attention and augment nauseogenicity of motion.

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In Experiment 1, subjects received two linear oscillatory motion changes: upright seated posture with horizontal motion through the x-axis of the head and body and upright seated posture with vertical motion through z-axis of head and body. The degree of motion sickness rating scale was 1 = no symptoms; 2 = mild symptoms, but no nausea; 3 = mild nausea and any additional symptoms; 4 = moderate nausea and any additional symptoms. The time to sickness ratings were significantly higher for horizontal than for vertical motion. Total symptom scores until motion stopped were significantly less for vertical than for horizontal.

There were three conditions in Experiment 2: upright seated with horizontal motion through x-body axis; upright seated posture with vertical motion through z-body axis; and supine posture with vertical motion through x-body axis. There were no significant analysis of variance effects for time to sickness rating 2. There was a significant effect of time to sickness rating 3 for motion condition for all subjects.

Through examination, means and specific comparisons revealed that time to reach sickness stages 3 and 4 was significantly less for horizontal than for vertical.

2.6 Simulator Sickness

2.6.1 Kennedy, Fowlkes, Berbaum, and Lilienthal, 1992

This paper discussed the usefulness of a motion sickness history questionnaire (MHQ) in the prediction of simulator sickness, a form of motion sickness experienced by individuals who train in ground-based flight simulators. Four MHQ scoring keys were compared. Navy and Marine Corps aviators (N = 456) completed the MHQ before their regular flight simulator training. All scoring keys were predictive of reported symptoms. The highest correlation was obtained with the simulator sickness (SS) key. Therefore, it was suggested that pilots use the SS key for self-testing so that they may be aware of their risk for simulator sickness. The use of this SS questionnaire may reduce safety risk, optimize training, and avoid flying restrictions imposed when symptoms are experienced.

2.7 Seasickness

2.7.1 Rolnick and Bles, 1989

The incidence of motion sickness in sailors working below deck is generally higher than in those who have the horizon as a visual reference on the bridge. This study looked at the possible benefit of a projected artificial horizon as a means of preventing seasickness. Twelve subjects were exposed to angular motion in a tilting room during three conditions: a) windows covered, allowing

15

no visual reference from the outside world; b) windows uncovered, allowing a partial view of the environment; and c) windows covered and a horizon projected onto the walls by a rotating laser beam. Subjects were exposed for 35 minutes in each condition while they performed different computerized tasks. There were fewer symptoms of motion sickness in the "artificial horizon" and "window" conditions. The presence of visual reference prevented the decrement in performance found in the "closed cabin" condition. These results suggest that a projected horizon may alleviate motion sickness aboard naval vessels and thus improve performance.

2.7.2 Wiker, Kennedy, McCauley, and Pepper, 1979

This study showed significant covariance between the magnitude of motion sickness symptomatology and the encounter direction of the vessel to primary swell. When the vessel was steaming into the seas or primary swell, motion sickness severity was greatest. Sea state, direction in which the vessel encountered the primary swell, and hull design played a major part in motion sickness provocation aboard marine vehicles.

2.8 Ground Vehicle Sickness

2.8.1 Rolnick and Lubow, 1991

Control was examined as a possible factor in motion sickness. It has been noted that being a driver instead of a passenger of a moving vehicle greatly reduces the likelihood of motion sickness just as pilots have been found to be less susceptible than other crew members. The purpose of this study was to empirically validate findings by Reason and Benson that motion sickness is not solely based on sensory information but on other influences such as the role of intention, feed- forward mechanism, or efferent-afferent correlation. Factors that have been suggested to explain driver immunity, including head movements, visual information, perceived control, predictability, and activity, are discussed. Twenty-two pairs of yoked subjects were exposed to nauseogenic rotation. Paired active and passive male subjects were placed in a two-seat rotating device. The active subject had a joystick with which he could control rotation. The passive subject was exposed to the same rotation without control. The heads of the subject pair were yoked by a rod attached to two helmets that were worn by the subjects. Only the active subject initiated head movements. The passive subject was asked to go along with the movements. Active (controllability) subjects were less likely to terminate before the experiment's completion, showed reduced motion sickness symptoms, and showed less decrement in their well-being, as compared to the passive subjects.

2.8.2 Vogel, Kohlhaas, and von Baumgarten, 1982

The purpose of this study was to test the hypothesis that otolith stimulation by linear acceleration in a car may elicit motion sickness. Thirty-eight healthy

16

subjects were accelerated in an ambulance car. Weak forward acceleration was alternated with brisk braking. Subjects were placed in one of the following positions: (1) sitting upright and facing forward in the car, (2) lying supine, head forward on a stretcher, (3) lying in a supine position, head backward. The experiment was terminated when 30 braking actions were completed or when the subject requested to stop. Motion sickness symptoms were observed and recorded after each trial via a scaling index that was weighted according to the strength of any particular symptom. The experiment clearly showed that horizontal linear acceleration in a car, coupled with the stop-and-go technique is effective in provoking motion sickness. More than 43% of the subjects became motion sick in less than 10 minutes.

2.8.3 Turner and Griffin, 1999

Turner and Griffin wanted to identify personal and environmental factors influencing individual susceptibility to motion sickness during road transport. A 14-item questionnaire was completed by 3,256 coach passengers pooled across 56 coach journeys. The questionnaire contained two measures of motion sickness, with a further item asking for information about sickness onset time. The first sickness measure, illness rating (IR), consisted of a 4-point subject rating of well- being. The second measure of motion sickness addressed specific symptoms. Passenger ages ranged from 8 to 80 years. Passenger characteristics, travel regularity, activity during travel, use of anti-motion sickness drugs, and self- reported motion sickness susceptibility were collected during the 56 coach journeys. Travel environment characteristics (visibility, temperature, and seating) were also recorded. The relationship of these variables to passenger illness and more specific motion sickness symptoms was examined. Overall, 28.4% of passengers reported feeling ill, 12.8% reported nausea, and 1.7% reported vomiting during travel coach. Sickness decreased with increasing age and travel experience. Females reported feeling ill more than their male counterparts by a ratio of four to three. Sickness was found to increase with poor forward visibility. Occurrence of illness was approximately three times higher for passengers with no view of the road ahead (mean, 34.6%) compared to those who could see the road ahead extremely well (mean, 12.7%). No relationships were found between the occurrence of sickness and temperature or time of travel. This research also suggests that habituation through greater travel regularity occurs independently of reductions that occur with age. Differences in the pattern of sickness responses exhibited by males and females suggest that females are more affected by a poor forward view. It is predicted that motion sickness in coaches may be reduced through improved saloon and window designs in order to maximize external passenger visibility.

2.8.4 Cowings, Toscano, DeRoshia, and Tauson, 1999.

The command and control (C2) vehicle (C2V) is required to support mobile operations and C2 within the confines of the vehicle. During early testing, it was discovered that human operators experienced motion sickness during moving

17

operations. As a result, the U.S. Army Research Laboratory's Human Research and Engineering Directorate and the National Aeronautics and Space Administration's Life Sciences Division performed a study to quantify the incidence and severity of motion sickness and any related performance decrement. The motion effects of the C2V parked, moving, and shortly halted were reported.

The main objectives were to (a) determine whether a significant difference existed among three internal configurations of the C2V or between seats within these vehicles; (b) determine whether a significant difference existed among the park, move, or short halt conditions; and (c) validate a method of converging indicators to assess the environmental impact of long space flights on crew members when a large sample of participants was used during ground-based operational conditions.

Twenty-four soldiers participated and were exposed to each of 12 seats (four seats in three configurations) for a 4-hour "cell". Three vehicle configurations were examined: (a) oblique, whereby the seat closest to the front faced forward and the other three seats were at 20-degree angle from the direction of travel; (b) perpendicular, whereby the front seat faced forward and the other three seats were at a 90-degree angle; (c) 4-forward, whereby all seats faced forward. Participants completed a motion sickness and mood scale and the delta cognitive battery for each cell. Half of the participants were instrumented to record physiological data. Each cell consisted of a parked administration of the test batteries, followed by two test batteries during motion and three test batteries during short halts.

Fifty-five percent of the participants reported moderate to severe motion sickness symptoms. The most frequently reported symptom was drowsiness (60% to 70% of participants), followed by headache (40% to 56%), sensations of increased warmth unrelated to ambient air temperature (40% to 45%), nausea (35% to 42%), and uncomfortable stomach sensations approaching nausea (20%). Short halts did not lessen symptoms. Performance was significantly degraded during moving operations versus the parked condition, with only a partial recovery during short halts. Performance degradation was comparable to blood alcohol levels at or above 0.08% (the legal limit of alcohol consumption in most states) in 35% of the soldiers during moving operations and 22% during short halts. No significant difference was reported between seat or vehicle in any of the measurements.

In summary, (a) there was no significant difference between vehicle configurations; (b) there was a negative impact on crew performance and health when subjects attended to visual computer screens while the vehicle was moving; (c) short halts did not substantially reduce symptom severity or

18

performance degradation; and (d) performance and mood were impaired in the vehicle, relative to pre- and post-tests conducted in a classroom facility.

It was suggested that the methodology used in this research project may be useful in the examination of the impact on soldiers in other land, sea, and air vehicles for which C2 functions similar to those of the C2V are planned. The examination of soldiers' physiological responses, performance, and mood states in these environments offers a more comprehensive assessment of the effectiveness of countermeasures for improving crew health and operational efficiency.

When asked about adaptation effects, Mr. Tauson responded via e-mail that the adaptation data were not included in the original report. As a result of some later questions, he reviewed the symptom data over time. The results are presented in two charts (see Figures 1 and 2). Basically, as would be expected, there was brief adaptation followed by an equalization in the first two-thirds of the chart. The increase in the last third is a little puzzling. Mr. Tauson believed that this was attributable to the introduction of a slightly different configuration or to the subjects' reaching some sort of endurance limit. It is possible that the subjects were reaching the point where their adaptive strategies were being overtaken by simple conditioning. In other words, the subjects' bodies knew what was going to happen.

1 \ \ \

Short Halt Moving Parked

1 1

1 1

1 »

w ,-A*

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8 9 10 11 12 13 14

Figure 1. Median Symptoms Over Time.

19

Figure 2. Mean Symptoms Over Time.

2.9 Air Sickness

2.9.1 Kennedy, 1975

Kennedy's objective was to show that training success can be predicted from motion sickness-related measures. The use of a motion sickness questionnaire to predict susceptibility to motion sickness or flight training success, depending on how the items are scored, was discussed. The motion sickness questionnaire (MSQ) was empirically validated against an experimental procedure for producing motion sickness symptomatology scores on the questionnaire, which were statistically related to the likelihood of successful aviation training. The MSQ inquired into each subject's exposure to motion, preferences for, and symptoms experienced in the devices. The subjects were then exposed to the Dial test, a standard and scorable procedure for producing motion sickness symptoms that is correlated with other motion sickness forms. A high score indicates resistance to MS since the score is the number of dial sequences attempted before emesis or requested nonparticipation. The group embedded figures test, another paper and pencil test, measured the field independence trait. The theory that motion sickness results from conflict of perceptual input is also discussed. High neuroticism scores were predictive for lack of success. Field independent persons seem less likely to attend to inappropriate fields. Field independence relates to an ability to separate figure from ground and to alternate between figure and ground. Also, the correlation between intellectual abilities scores (numerical and verbal ability, and mechanical aptitude) and field independence showed that common factors relating to flight training exist.

20

2.9.2 Jones, Levy, Gardner, Marsh, and Patterson, 1985

It was demonstrated that well-motivated fliers (military student pilots) with chronic, severe airsickness who were unresponsive to other treatment methods could return to unrestricted flying by using biofeedback-mediated self-regulation to enhance relaxation and lower autonomic arousal once nausea occurred. Elements of biofeedback training, autogenic training, mental imagery, deep muscle relaxation, systematic desensitization, diaphragmatic breathing, and occasional brief psychotherapeutic interventions were included in the application of the technique. Programs were tailored to each flier's particular personality style and autonomic response pattern. There was only a 15% failure rate of the biofeedback technique, attesting to this approach's effectiveness.

2.9.3 Johnson and Mayne, 1953

Earlier research showed that individual differences in susceptibility to motion sickness depend to a large extent on concurrent head movement in response to the movements imposed on the body as a whole. Statistics gathered from World War II show that airborne infantry are particularly susceptible to air sickness. As a result, it was decided that trials would be conducted with Army personnel in the process of training as paratroopers. In approximately 700 tests with more than 500 subjects (Canadian paratroop trainees), results showed that headrests have a consistent effect in preventing air motion sickness during air transportation in all turbulence conditions. It was possible to predict that in 95 of every 100 flights, between 60% to 83% of the susceptible Canadian paratroop trainees could avoid airsickness with the use of a headrest device during "normal turbulence." There is some indication that the incidence of air motion sickness in soldiers decreases as the time since the last meal increases; no general conclusions can be made with confidence.

3. Discussion

The literature revealed a myriad of possible causal factors and types and suggested remedies to reduce or potentially eliminate motion sickness symptoms and related performance decrements. Demographic factors that may influence motion sickness susceptibility are gender, exposure history, receptivity, adaptability, and personality characteristics. Unfamiliar and unexpected optical information may also provoke motion sickness. The primary theory of motion sickness is that of sensory conflict whereby signals from the visual, vestibular, and non-vestibular systems conflict with one another or with previous experience.

Some motion sickness symptoms in immersive virtual reality may be the result of resolution, field of view, and system lag. It is unlikely that sensory conflict is the

21

Single causal factor in immersive reality. The impact of resolution and FOV on motion sickness is unclear. Woodman and Griffin (1977) reported that direction of head movement during Coriolis stimulation has a large effect on nausea. Rotating the head downward (pitched forward) rather than upward increases motion sickness symptoms. Vertical motion rather than horizontal has been found to be more provocative. Golding et al. (1995) revealed that upright versus supine body position and stimulation through the X-axis versus the Z-axis both enhance nauseogenicity of low frequency linear oscillation and these effects are additive. Active control, such as a driver or pilot compared to passengers, was found to play a role in motion sickness susceptibility and well-being. Active versus passive showed less decrement in well-being and reduced symptoms. Rolnick and Lubow (1991) showed that subjects who had control over their motion environment reported significantly fewer motion sickness symptoms and less of a decrement in well-being. Vogel et al. (1982) published that horizontal linear acceleration in a car when the stop-and-go technique was used is effective in provoking motion sickness. More than 43% became motion sick in less than 10 minutes. Finally, Cowings et al. (1999) reported a negative impact on crew performance and health when subjects attended to computer screens while the vehicle was moving.

Three primary classes of motion sickness symptoms were identified in the literature. The first class involves the vestibular system whereby there is a disruption of perceptual and sensorimotor activities, such as disorientation, disequilibrium, and inappropriate vestibulo-ocular or vestibulo-spinal reflexes. The second class has a perceptual origin and consists of many autonomic symptoms such as pallor, drowsiness, salivation, sweating, nausea, and vomiting. The third class includes symptoms such as mood changes, lethargy, and sleep and is referred to as the "sopite syndrome". This syndrome is a more recently discussed symptom class. None of the journal articles reviewed in this search specifically address the sopite syndrome. The causes of each symptom class vary over a wide range of mechanisms, including an individual's previous experience with motion and subsequent expectations.

The average exposure time in these research efforts was 30 minutes. In a combat environment, soldiers have to endure long miles in confined vehicles for several hours. Golding and Kerguelen were the only researchers who actually discussed recovery times. They reported that the slowest recovery time from low-frequency linear oscillation was 7 minutes. They warned that the subjective recovery time may be an underestimate of residual after-effects. Consequently, we do not know how soon a soldier could return to a full performance level after experiencing motion sickness.

Training techniques were discussed in 4 of the 21 journal articles reviewed. Toscano and Cowings (1982) revealed that subjects who were taught to control autonomic responses could withstand Coriolis acceleration stress as much as

22

three times longer after training. Dobie et al. (1989) showed that a combination of desensitization and cognitive therapy was most effective at increasing resistance to visually induced disorientation. Jones et al. (1985) reported a failure rate of only 15% for biofeedback-mediated self-regulation for enhancement of relaxation and lowering of autonomic arousal once nausea had occurred. Of 53 fliers grounded for chronic, severe motion sickness, 79% returned to and maintained satisfactory operational flying status, while 6% were partially successful following treatment. Dobie and May (1990) showed that tolerance in using one device can transfer to another motion experience. It appears that the best way to produce generalized motion adaptation is to subject the individual to a very provocative, perhaps vestibular, mode of stimulation.

Some other measures that may reduce motion sickness include seating configuration, vehicle design, positive head restraint, adequate external visual reference or artificial horizon, biofeedback, autogenic feedback training (individual taught to control autonomic responses), mental imagery, diaphragmatic breathing, and psychotherapeutic interventions.

Researchers have "standardized" several cognitive and physical performance measures to assess motion sickness severity, but few have addressed militarily relevant measures. Rolnick used the memory comparison task (MCT) and a dual task to assess performance. MCT is a computerized reaction time task. DT consisted of a tracking task and a continuous memory task. These would be applicable to drivers, commanders, command and control personnel, or infantry for example.

In a protocol to validate a motion sickness history questionnaire, ARL used a rail walk test (Heath, 1943) to measure locomotor coordination, a multi-task monitoring environment called SYNWORK (Elsmore, 1994; Lieberman, Mays, Shukitt-Hale, Chinn & Tharion, 1996) to measure cognitive performance, and an aiming performance test using the Noptel ST-2000 system. The rail-walking test consisted of three wooden rails 9 feet by 4 inches, 9 feet by 2 inches, and 6 feet by 1 inch. The height of each rail is sufficient to avoid contact of the participant's foot with the floor. Each rail was divided into units of feet. Each participant was asked to train on each rail by walking heel to toe. Scores were recorded before and after the study trial. The raw score was the total number of feet walked without the participant stepping off. SYNWORK consisted of a synthetic multi- task monitoring work environment for a personal computer. This test required continuous monitoring of four tasks: Sternberg memory; 3-column addition; visual tracking; and signal detection. The stimulation incorporated workload, resource sharing, and contingency factors. Scores were recorded before and after the trial. Aiming performance with the Noptel ST-2000 consisted of an optical unit attached to an air gun (no projectile used), a reflector attached to the target, and an interface box of electronics that connects the optical unit to a personal computer for data display, analysis, and storage.

23

Motion sickness severity was often defined through ratings such as those from a study performed by Golding et al. (1995): ratings 1 (no symptoms), 2 (mild symptoms, no nausea), 3 (mild nausea and any additional symptoms), and 4 (moderate nausea and any additional symptoms). These ratings varied from study to study.

4. Recommendations and Conclusions

The literature search revealed several potential motion sickness prevention methods. It is recommended that these prevention methods be researched to determine whether a benefit exists for indirect vision driving. The operator's seat should be designed to offer head restraint to limit independent head movement. This has been known to be highly effective in reducing motion sickness incidence. There is also considerable evidence that adopting the supine position reduces motion sickness symptoms.

During design, consideration should also be given to wave frequency in vertical periodic motion. It was determined that sickness incidence diminishes with increasing frequency and is nearly nonexistent above 0.6 Hz. Therefore, caution has been given against "smoothing" ride characteristics by reducing high frequency motion at the risk of increasing low frequency bands, thereby increasing the risk of motion sickness.

Another potential area of consideration is perceptual adaptation through prior exposure or training session. Unfamiliar and unexpected optical movement information can lead to motion sickness. In a moving combat vehicle, there will likely be many instances of unexpected optical information because of the jolts of riding and lack of situational understanding, for example. Little information was found about the effects of motion on perceptual and cognitive performance. Given that Future Combat Systems are emphasizing cognitive performance while the vehicle is moving, this is a major void in the research literature. Further research is needed in this area to identify the impacts on the various types of roles performed (e.g., command and control, infantry, medical, or vehicle operator). Emphasis should be placed on the organized development of measures sensitive to these roles and their relationship to vehicle characteristics.

Another possible method is to bring visual and vestibular cues into alignment through display resolution, FOV, and system lag. The impact that improved resolution or wide versus narrow FOV has on motion sickness is unclear. However, it is suggested that motion sickness symptoms increase with system lag. Further evidence suggests that sickness is caused by lag variation, not lag by itself. Display update lags may induce a conflict when time between head

24

movement and visual scene become discernible, for example. This issue weighs heavily with Future Combat Systems' use of numerous displays while moving.

Many researchers used motion sickness history questionnaires (MSHQ) as a means to predict susceptibility. MSHQs were designed to identify an individual's pre-exposure background or life's experiences to motion such as simulation, aviation, shipboard, and virtual environment (Kennedy, 1975; Miller & Graybiel, 1971). This questionnaire type varied since it is adapted to the specific research at hand. Dobie uses two rating checklists; one is an activity (individual experience) checklist and the other is a motion sickness (response to activities experienced) checklist. Dobie adds activities such as carnival rides, swings, elevators, and bicycles to his checklists. Another questionnaire type often used in conjunction with the MSHQ was a symptomatology questionnaire (Kennedy, 1975) that was used to rate the type and degree of motion sickness experienced during a specific exposure.

25


26

References

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Brand, J.T., & Reason, J.J. (1975). Motion sickness. London: Academic Press.

Cowings, P.S., & Toscano, W.B. (1982). The relationship of motion sickness susceptibility to learned autonomic control of symptom suppression. Aviation, Space, and Environmental Medicine, 53(6), 570-575.

Cowings, P.S., Toscano, W.B., DeRoshia, C, & Tauson, R.A. (1999). The effects of the command and control vehicle (C2V) operational environment on soldier health and performance (ARL-MR-468). Aberdeen Proving Ground, MD: U.S. Army Research Laboratory.

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Lieberman, H.R., Mays, M.Z., Shukitt-Hale, B., Chinn, K.S.K., & Tharion, W.J. (1996). Effects of sleeping in a chemical protective mask on sleep quality and cognitive performance. Aviation, Space, and Environmental Medicine, 67, 841-8.

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Manning, G.W. (1943). Acclimation to swing sickness. Report to Assoc. Comm. on Aviation Medicine Research. Canada: NRC.

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Rolnick, A., & Lubow, R.E. (1991). Why is the driver rarely sick? The role of controllability in motion sickness. Ergonomics, 34(7), 867-879.

Sharkey, T., McCauley, M., Schwirzke, M., Casper, P., & Hennessy, R. (February 1995). The effects of whole body motion, head-mounted display, and hand control device on tracking performance. Warren, MI: U.S. Army Tank-Automotive Command, TARDEC.

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Turner, M., & Griffin, M (1999). Motion sickness in public road transport: Passenger behavior and susceptibility. Ergonomics, 42(3), 444-461.

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Wiker, S.F., Kennedy, R.S., McCauley, M.E., & Pepper, R.L. (1979). Susceptibility to seasickness: Influence of hull design and steaming direction. Aviation, Space, and Environmental Medicine, 50(10), 1046-1051.

Woodman, P.D., & Griffin, M.J. (1997). Effect of direction of head movement on motion sickness caused by Coriolis stimulation. Aviation, Space, and Environmental Medicine, 68, 93-8.

Yardley, L. (1992). Motion Sickness and Perception: A reappraisal of sensory conflict approach. British Journal of Psychology, 83,449-471.

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The

mai

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tha

t rol

l an

d pi

tch

mot

ion

resu

lt in

pe

rfor

man

ce d

eter

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tion

and

a w

ell-

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ent.

The

se

effe

cts

may

be

redu

ced

by

prov

idin

g a

visu

al r

efer

ence

fra

me,

ev

en a

sin

gle

proj

ecte

d ar

tific

ial

hori

zon.

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stat

e, v

esse

l en

coun

ter

dire

ctio

n to

the

prim

ary

swel

l an

d hu

ll de

sign

cha

ract

eris

tics

play

a

maj

or p

art

in t

he p

rovo

catio

n of

M

S ab

oard

mar

ine

vehi

cles

. The

89

Nav

y ex

peri

men

tal

vess

el

(sem

i-su

bmer

sibl

e pl

atfo

rm o

r SS

P), w

hich

rep

rese

nts

a ra

dica

l ch

ange

fro

m t

he tr

aditi

onal

mon

o-

hull

ship

des

ign,

pro

duce

d on

ly

very

min

or l

evel

s of

illn

ess, w

hich

c .0 re

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ere

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sed

to a

ngul

ar m

otio

n in

a ti

lting

roo

m

duri

ng th

ree

expe

rim

enta

l co

nditi

ons: a

) C

lose

d ca

bin

(CC

) -

Win

dow

s co

vere

d, n

o vi

sual

ref

eren

ce

from

the

out

side

wor

ld;

b) W

indo

ws

(W)

unco

vere

d,

a pa

rtia

l vi

ew o

f the

env

iron

men

t; c) A

rtif

icia

l H

oriz

on (

AH

) -

Win

dow

s co

vere

d, a

hor

izon

pr

ojec

ted

on t

he w

alls

by

a ro

tatin

g la

ser

beam

. Fo

r M

S, a

n A

NO

VA

for

rep

eate

d m

easu

res

reve

aled

a

sign

ific

ant m

ain

effe

ct f

or th

e co

nditi

ons

(F =

4.0

6,

p <

0.05

). A

post

erio

ri a

naly

sis

show

ed a

sig

nifi

cant

di

ffer

ence

bet

wee

n C

C a

nd A

H c

ondi

tions

(t =

1.8

2,

p <

0.05

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d a

sign

ific

ant d

iffe

renc

e be

twee

n W

an

d C

C c

ondi

tions

(t =

2.9

4, p

< 0

.05)

. Fo

r w

ell-

be

ing,

an

AN

OV

A f

or r

epea

ted

mea

sure

s sh

owed

a

sign

ific

ant e

ffec

t for

exp

osur

e du

ratio

n (F

= 1

1.86

, p

< 0

.05)

but

onl

y a

mar

gina

l ef

fect

for

con

ditio

ns (

F =

2.74

, p <

0.0

8).

For

perf

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REPORT DOCUMENTATION PAGE Form Approved OMR Nn 0704-01 flfi

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503.

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE

May 2002

3. REPORT TYPE AND DATES COVERED

Final

4. TITLE AND SUBTITLE


5. FUNDING NUMBERS

AMS: 622716 PR: AH70

6. AUTHOR(S)

Burcham, P. M. (ARL)

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

U.S. Army Research Laboratory Human Research & Engineering Directorate Aberdeen Proving Ground, MD 21005-5425

8. PERFORMING ORGANIZATION REPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

U.S. Army Research Laboratory Human Research & Engineering Directorate Aberdeen Proving Ground. MD 21005-5425

10. SPONSORING/MONITORING AGENCY REPORT NUMBER

ARL-MR-504

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION/AVAILABILITY STATEMENT


12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

A review of the literature about motion-induced cognitive and perceptual decrements and about motion sickness was conducted to identify screening methods and mitigation techniques and to gain estimates of the portion of population affected. Screening and mitigation techniques that show promise for indirect driving will be evaluated in imminent laboratory and field experiments.

14. SUBJECT TERMS

motion sickness susceptibility simulator sickness

15. NUMBER OF PAGES

55 16. PRICE CODE

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Unclassified

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Unclassified

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Unclassified

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NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89) Prescribed by ANSI Std. Z39-18 51 298-102

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