ARMY RESEARCH LABORATORY

Motion Sickness Literature Search

Patricia M. Burcham

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Army Research Laboratory

Aberdeen Proving Ground, MD 21005-5425

ARL-MR-504 May 2002

Motion Sickness Literature Search

Patricia M. Burcham

Human Research & Engineering Directorate

Approved for public release; distribution is unlimited.
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

in
INTENTIONALLY LEFT BLANK

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 vestibuloocular 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 (crosscoupled 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 nonvertical 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.

2

In 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

10
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 highlysusceptible 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 probabilitymonitoring 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

11
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).

12
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"2root 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

13
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.

/

}

^^§i^

\i

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 fivepoint 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.

14
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, feedforward 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 wellbeing. 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 selfreported 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

*

"\' L

V*\

w

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 multitask 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
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26
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30
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The main conclusion was that roll

and pitch motion result in

performance deterioration and a

well-being decrement. These

effects may be reduced by

providing a visual reference frame,

even a single projected artificial

horizon.

Sea state, vessel encounter

direction to the primary swell and

hull design characteristics play amajor part in the provocation of

MS aboard marine vehicles. The89 Navy experimental vessel

(semi-submersible platform or

SSP), which represents a radical

change from the traditional monohull ship design, produced onlyvery minor levels of illness, which

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Ss were exposed to angular motion in a tilting room

during three experimental conditions: a) Closedcabin (CC) - Windows covered, no visual reference

from the outside world; b) Windows (W) uncovered,

a partial view ofthe environment; c) Artificial

Horizon (AH) - Windows covered, a horizon

projected on the walls by a rotating laser beam. For

MS, an ANOVA for repeated measures revealed a

significant main effect for the conditions (F

= 4.06,

p < 0.05).

A posteriori analysis showed a significant

difference between CC and AH conditions (t

= 1.82,

p < 0.05) and a significant difference between

W

and CC conditions (t

= 2.94,

p < 0.05). For wellbeing, an ANOVA for repeated measures showed a

significant effect for exposure duration (F

= 11.86,

p < 0.05) but only a marginal effect for conditions (F

= 2.74,

p < 0.08). For performance measures, an

ANOVA for repeated measures showed a significant

effect for conditions (F

= 3.19,

p < 0.05) and for

time (F = 12.18,

p < 0.01).

A posteriori analysis

indicated that condition CC was significantly

different from no motion (NM) (t

= 2.35,

p < 0.05)

and from

W (t = 2.05,

p < 0.05) but not from AH.

Significant covariance between the magnitude ofMS symptomatology and the encounter direction of

the primary swell {p < 0.01). Significant correlations

were found between sickness severity and subjectconcentration, fatigue, urine production, and urinespecific gravity.

Performance

measure

Memory

Comparison Task(MCT) - acomputerized

reaction

time task;

Dual Task

(DT) - consisted of atrackingtask and acontinuous

memory

task; a MSquestionnaire and a

verbalrating of

well-being

100 (excellent) and 0

(very bad).

Subjective

symptomquestionnaire,objectiveevidence - reportingof

vomiting

episodes

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REPORT DOCUMENTATION PAGE Form Approved

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

May 2002

3. REPORT TYPE AND DATES COVERED

Final

4. TITLE AND SUBTITLE

Motion Sickness Literature Search

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

Approved for public release; distribution is unlimited.

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

17. SECURITY CLASSIFICATION

OF REPORT

Unclassified

18. SECURITY CLASSIFICATION

OF THIS PAGE

Unclassified

19. SECURITY CLASSIFICATION

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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