Roll Vection Research Articles

Age-dependent perturbation of the perceptual and postural vertical by visual roll vection and susceptibility to motion sickness in children

BackgroundThe visual contribution to the perceptual and postural vertical is mediated by a multisensory integration process and may relate to children’s susceptibility to motion sickness that is hypothesized to arise from intersensory conflicts.ObjectiveTo analyze the maturation of visual contribution to the perceptual and postural vertical in conjunction with the motion sickness susceptibility in childhood.MethodsIn 81 healthy children (aged 2–17 years; 57 females), adjustments of the subjective visual vertical and posturographically tested mediolateral displacements of body sway were measured during free upright stance and large-field visual motion stimulation in the roll plane (roll vection). Motion sickness susceptibility was assessed by taking the history of parents and children.ResultsVection-induced tilts of the visual vertical showed a linear age-dependent decrease with largest tilts in the youngest (2–7 years; median of 20°) and smallest tilts in the oldest age group (13–17 years; median of 9–10°). Analogously, postural tilts as measured by mediolateral body sway were greatest in the youngest and smallest in the oldest age group. In contrast, motion sickness susceptibility was lowest in the youngest and highest in the oldest age group and exhibited an inverse correlation with vection-induced tilts of the visual vertical.ConclusionRoll vection-induced tilts of the visual and postural vertical exhibited a similar age-dependent course with the greatest effects in the youngest and the least effects in the oldest age group, the latter of which exhibited the highest susceptibility to motion sickness.

Orientation-defined visual rotation significantly affects observer's perceived self-motion

It is believed that visual self-motion perception (vection) can be effectively induced only in the case where the inducer's motion is defined by luminance modulation. In this study, psychophysical experiments examining the potential effects of visual motion defined by features other than luminance on visual self-motion perception (vection) were conducted, employing orientation-defined rotation (so-called fractal rotation) as a visual inducer. The experiments clearly indicate that orientation-defined visual rotation can strongly induce an observer's perceived self-rotation (roll vection), although it was significantly weaker than that induced by luminance-defined rotation. In the case where the orientation and luminance rotations were combined and presented simultaneously, perceived self-rotation was mainly determined by the luminance rotation when both factors were set to rotate in consistent or inconsistent directions. These results suggest that feature-defined visual motion containing no luminance modulation has the potential to contribute to visual self-motion perception.

20 Optic Flow Stimuli Effects on Standing Balance in Young and Older People with Low and High Fall Risk

Abstract Introduction Optic flow stimuli can destabilise postural control, especially those with increased visual field dependence. This study aimed to examine the effects of optic flow stimuli on postural stability between: 1) younger and older adults; and 2) low-falls-risk and high-falls-risk older adults. Methods 76 participants were grouped into ‘young’ (20-40 years, n=25), and ‘old’ (≥65 years, n=51); the latter was further stratified into ‘old-LFR’ (low fall risk, n=27) and ‘old-HFR’ (high fall risk, n=24). Participants stood on a force platform in a dark room with motion capture markers on the head, torso and lower limb. Optic flow stimuli were projected on a large screen encompassing the field of view as moving white dots for 30 seconds in four different conditions: radial expansion, radial contraction, circular (roll vection) anticlockwise and circular clockwise. Postural control was calculated from center of pressure (COP) and lower limb joint and trunk angles; changes between baseline (static dots) and optic flow conditions were compared between groups. Results Optic flow stimuli led young and older participants to shift their COP in the expected direction for each stimulus condition (forward for expansion, backward for contraction, left for anticlockwise, right for clockwise). For radial expansion, significantly increased anteroposterior sway was found in old-LFR and old-HFR (p≤0.001) but not \young (p≥0.17). Similar results were seen for radial contraction. For circular clockwise, significantly increase mediolateral sway was found in old-HFR (p=0.002) but not young (p=0.912) or old-LFR (p=0.749). Results differed for circular anticlockwise, with greater changes seen in anteroposterior sway compared with mediolateral, particularly in old-HFR. No stimuli by group interaction effects were seen in body kinematics. Conclusions Optic flow stimuli have a more destabilising effect on balance in older than younger adults, particularly those at increased risk of falling.

Roll vection in migraine and controls using inertial nulling and certainty estimate techniques.

Vection is an illusory perception of self-motion that occurs when a visual motion is presented in the majority of the visual field. We used certainty estimate (CE) and inertial nulling (IN) techniques to study the effect of visual stimuli on roll perception in 10 migraine and 9 control subjects. A visual roll stimulus was presented for 1 to 8s. For the IN method, an inertial stimulus was delivered during the final 1s of the visual stimulus during which subjects judged the direction of perceived motion. The inertial motion was varied to find the point of subjective equality (PSE) at which both responses were equally likely to be reported. For the CE trials, the same durations of visual motion were used but without inertial motion and subjects rated their certainty of motion on a scale of 0–100. The overall difference in PSE between 1s and 8s subjects is significant (p = 0.03). Migraineurs had a ten fold larger effect in IN studies in the 8s than 1s (p = 0.01), but controls did not have a significant difference (p = 0.72). Unlike the control population, in migraineurs the perception of roll increased significantly with the duration of the visual stimulus. There was a large variation between subjects with both the CE and IN measures. The CE measure was poorly correlated with IN measures but demonstrated a similar trend with larger variation between subjects.

Visual Field Dependence Is Associated with Reduced Postural Sway, Dizziness and Falls in Older People Attending a Falls Clinic.

Moving visual fields can have strong destabilising effects on balance, particularly when visually perceived motion does not correspond to postural movements. This study investigated relationships between visual field dependence (VFD), as assessed using the roll vection test, and reported dizziness, falls and sway under eyes open, eyes closed and optokinetic conditions. Ninety five falls clinic attendees undertook the roll vection test (i.e. attempted to align a rod to the vertical while exposed to a rotating visual field). Sway was assessed under different visual conditions by centre of pressure movement. Participants also completed questionnaires on space and motion discomfort, fear of falling, depression and anxiety. Thirty four (35.8%) participants exhibited VFD, i.e. had an error > 6.5º in the roll vection test. Compared to participants without VFD, participants with VFD demonstrated less movement of the centre of pressure across all visual conditions, were more likely to report space and motion discomfort and to have suffered more multiple falls in the past year. VFD was independent of fear of falling, anxiety and depression. VFD in a falls clinic population is associated with reduced sway possibly due to a stiffening strategy to maintain stance, dizziness symptoms and an increased risk of falls.

The effects of local rotation on roll vection induced by globally rotating visual inducer

A visual stimulus rotating globally along an observer's line of sight can induce the illusory perception of self-rotation in the opposite direction (roll vection). Psychophysical experiments were conducted to examine the effects of local rotations of visual elements of the stimulus that were manipulated independently of the global rotation. The results indicated that the addition of local rotations inconsistent with the global rotation (assumed to be the primary inducer of roll vection), generally decreased the strength of perceived self-rotation. The uniformity of orientation of the elements composing the global visual pattern and the visual polarities assigned to each visual element, i.e., intrinsic directionality concerning up and down, were observed to function as modulators of the effects of the local rotation. These results suggested that local motion signals arising from independent rotations assigned to each element of a visual object cannot be ignored in the perceptual mechanism underlying roll vection.

Visual Jitter Inhibits Roll Vection for an Upright Observer

It is widely known that visual jitter convoluted with an expanding optical flow can robustly enhance an observer's illusory perception of forward self-motion (eg Palmisano et al 2000 Perception 29 57-67). In the present investigation I examine the effects of visual jitter on visually induced self-rotation (roll vection). The results showed that the strength of roll vection was decreased under conditions where the visual jitter was convoluted into the rotating visual stimulus. Although the extent of the decrement differed according to the amplitude and direction of the jitter, visual jitters in any direction with any amplitude can significantly reduce vection strength, at least under the conditions examined in the present experiment. The perceptual process underlying jitter effects on vection is discussed in the context of visuo-vestibular conflict in perception of self-motion.

Pre-flight sensorimotor adaptation protocols for suborbital flight1

Commercial suborbital flights, which include 3-5 minutes of 0 g between hyper-g launch and landing phases, will present suborbital passengers with a challenging sensorimotor experience. Based on the results of neurovestibular research in parabolic and orbital flight, and the anticipated wide range of fitness and experience levels of suborbital passengers, neurovestibular disturbances are likely to be problematic in this environment. Pre-flight adaptation protocols might alleviate some of these issues. Therefore, we describe a set of sensorimotor tests to evaluate passengers before suborbital flight, including assessment of the angular vestibulo-ocular reflex (VOR), ocular skew and disconjugate torsion, subjective visual vertical, and roll vection. Performance on these tests can be examined for correlations with in-flight experience, such as motion sickness, disorientation, and visual disturbances, based on questionnaires and cabin video recordings. Through an understanding of sensorimotor adaptation to parabolic and orbital flight, obtained from many previous studies, we can then suggest appropriate pre-flight adaptation procedures.

Visual Rotation Axis and Body Position Relative to the Gravitational Direction: Effects on Circular Vection

The visual–vestibular conflict theory asserts that visual–vestibular conflicts reduce vection and that vection strength is reduced with an increasing discrepancy between actual and expected vestibular activity. Most studies support this theory, although researchers have not always accepted them. To ascertain the conditions under which the theory of the visual–vestibular conflict can be applied, we measured circular vection strength accompanied by manipulation of the visual–otolith conflict by setting the axes of visual global motion (pitch, roll, and yaw) as either earth-horizontal or earth-vertical, using three different body positions (supine, left-lateral recumbent, and sitting upright). When the smaller stimulus was used, roll vection strength was greater with the visual–otolith conflict than without it, which contradicts the visual–vestibular conflict theory. We confirmed this result, as observers were able to distinguish circular vection from an illusory body tilt. Moreover, with observers in an upright position, the strength of yaw vection, which does not involve the visual–otolith conflict, increased and was almost equal to that of roll vection, which involves the visual–otolith conflict. This suggests that if the visual stimulus covers the entire visual field, the strength of circular vection around the earth-vertical axis exceeds that around the earth-horizontal axis, which is a finding consistent with the visual–vestibular conflict theory.

Effects of Viewpoint Jitters Onf Roll Vection

It has been revealed that random viewpoint jitters or periodical viewpoint oscillation superimposed in visual stimulus which simulates the observer's self-motion can enhance visually induced self-motion perception (vection), even if there are sustained conflicts between visual and vestibular information. The effects of jitter/oscillation have been confirmed both using forward self-motion induced by expanding display and horizontal linear self-motion induced laterally moving visual pattern. In the present investigation, we examined whether jitter/oscillation advantage would affect visually induced self-rotation (roll vection) induced by rotating visual pattern. In psychophysical experiments with 12 undergraduate participants, we compared perceived strength of roll vection between the stimulus conditions where simulated viewpoint jitters were superimposed or not. The results indicated that viewpoint jitters significantly weakened strength of perceived self-rotation. On the other hand, random roll component superimposed in pure radial expanding pattern can enhance illusory forward self-motion. These results suggest that the effects of viewpoint jitter would affect differently on linear vection induced by expanding optical flow and circular vection induced by visual rotation.

Interaural self-motion linear velocity thresholds are shifted by roll vection.

The otolith organs respond equivalently to changes in gravitational force due to head tilt and to changes in inertial force due to linear acceleration. It has been shown that the central nervous system (CNS) uses internal models of the laws of physics to distinguish tilt from translation. Models with these internal models predict that illusory tilt, if large enough, will be accompanied by an illusion of linear motion. To investigate this prediction, we measured interaural, self-motion, direction-detection thresholds in darkness and with roll optokinetic stimulation. Each lateral translation consisted of a single cycle of sinusoidal acceleration, after which subjects indicated whether they translated to the left or right. We found that the interaural direction-detection threshold measured during clockwise and counterclockwise optokinetic stimulation shifted in opposite directions relative to thresholds in darkness. Using a generalized linear model, we determined that this finding was statistically significant (P < 0.005) and is consistent with the prediction that illusory tilt should be accompanied by a non-zero neural estimate of linear velocity that, if large enough (supra-threshold), contributes to translation perception.

Localization of Sound Presented Via a Spatial Audio Display during Visually Induced Vection in Pitch, Roll, and Yaw

There is growing interest in the potential application of 3D audio displays to impart spatial information to aircraft pilots. As the aviation environment is dynamic, the effect on sound localization of the visual and vestibular stimulation resulting from motion during flight needs to be assessed. In this study, we investigated whether sound localization is affected by visual cues to self-motion. Participants localized bursts of broadband acoustic noise presented from the frontal hemifield under conditions of yaw, pitch, and roll vection (around the z-, y-, and x-axis, respectively) induced by wide-field visual motion of a projected sinusoidal grating. Lateral and elevation components of localization errors were measured. Average signed lateral and elevation errors were less than 1.6 degrees for all vection conditions. The effects of vection condition on lateral and elevation errors were not statistically significant. Also, the interactions between vection condition and sound-source location for these errors were not significant. The magnitudes of the 95% confidence intervals for the differences in lateral and elevation errors between the no-vection condition and each of the other vection conditions did not exceed 3 degrees. In the presence of visual cues to yawing, pitching, or rolling self-motion, the perception of auditory space is generally consistent with the available head-centered auditory cues to sound-source location. These results support the application of 3D audio displays in dynamic visual environments such as that experienced during flight.

Increased Role of Peripheral Vision in Self-Induced Motion in Patients with Age-Related Macular Degeneration

The contribution of peripheral vision in inducing self-motion (vection) was investigated in people with bilateral age-related macular degeneration (AMD). Eleven patients with bilateral AMD and dense central scotomas with no islands of functional central retina and 12 age-matched control subjects were exposed to random-dot patterns projected on a large screen. The dots either moved from left to right, inducing linear vection, or rotated about the roll axis, inducing roll vection. Latency, total vection time, and objective and subjective measures of tilt were recorded. The patients with AMD experienced shorter latencies than did the age-matched control participants, but the total vection time in both conditions and tilt during roll vection were the same in both groups. There was a positive correlation between objective tilt and subjective measures of tilt in the AMD, but not in the age-matched control group. There was a negative relationship between absolute scotoma size and latency. Two main conclusions were drawn. First, the role of peripheral vision in inducing vection is enhanced in people with bilateral central vision loss. Second, people with bilateral AMD adapt successfully to a moving environment (they do not experience vection longer, nor do they tilt more) and are more aware of their postural position than are age-matched control subjects.

Gait deviations induced by visual stimulation in roll

Locomotion control uses proprioceptive, visual, and vestibular signals. The vestibular contribution has been analyzed previously with galvanic vestibular stimulation (GVS), which constitutes mainly a virtual head-fixed rotation in the roll plane that causes polarity-specific deviations of gait. In this study we examined whether a visual disturbance has similar effects on gait when it acts in the same direction as GVS, i.e., when roll vection is induced by head-fixed visual roll motion stimulation. Random dot patterns were constantly rotated in roll at +/-15 degrees /s on a computer-driven binocular head-mounted display that was worn by eight healthy participants. Their gait trajectories were tracked while they walked a distance of 6 m. A stimulation effect was observed only for the first three to four steps, but not for the whole walking distance. These results are similar to the results of previous GVS studies, suggesting that in terms of the direction of action visual motion stimulations in the roll plane are similar to GVS. Both kinds of stimulation cause only initial balance responses in the roll plane but do not contribute to the steering of gait in the yaw plane.

Type of Motion in Inverted Self-Motion Perception Induced by a Foreground Stimulus

Slowly moving foreground induces an illusory self-motion perception in the same direction as its motion direction (inverted vection). In this study, the effects of motion type of the foreground stimulus on inverted vection were investigated using a sample of 3 men and 1 woman. As indices of perceived strength of the inverted vection, duration and estimated magnitude were measured. Analysis of the psychophysical experiment indicated that a translating foreground induced inverted linear vection in the same direction as the stimulus motion. However, a rotating foreground did not induce an inverted roll vection. Statistical analyses indicate that there is a significant difference between two foreground motion conditions (Duration: t3=14.54, p <.01; Estimation: t3=16.92, p<.01). This result supports the hypothesis that eye-movement information is responsible for the occurrence of inverted vection.

回旋性視覚刺激下の自覚的垂直位（Ｓｕｂｊｅｃｔｉｖｅ Ｖｉｓｕａｌ Ｖｅｒｔｉｃａｌ：ＳＶＶ）とｖｅｃｔｉｏｎ

Previous experiments have established that visual stimulation in the roll plane causes people to feel roll vection. However, few experiments have been aimed at characterizing the relationship between changes in the subjective visual vertical (SVV) and the generation of vection. In this experiment we investigate the relationship between SVV, a quasi-subjective parameter, and vection, the visually induced perception of selfmotion. We observed three different patterns of change in SVV. Even with fixed visual stimuli, in many cases SVV changed continuously. These results suggest that conflicts among different sensory inputs produce dynamic changes in the priority of these sensory inputs. The longer vection is perceived, the more predominant the visual sensory input becomes.

視覚誘発性自己回転感における男女差

Vestibular function gradually deteriorates with aging, however, its behavioral consequences are not easily recognized due to a substitution process by other sensory modalities such as visual or proprioceptive inputs. Not only age but also gender can make a significant difference in these functions. To reveal such hidden substitution processes by visual signals, the measurement of the static as well as the dynamic subjective visual vertical was performed in 65 healthy subjects of different age. The static subjective visual vertical was found to be stable among all subjects, whereas the shift of the dynamic subjective visual vertical during rotation of the background scene gradually increased with age. There was a significant difference between males and females in this trend. Females usually showed greater deviation with increased age. This finding indicates that the hormonal differences between genders make a difference in generation and recognition of roll vection.

Phobic postural vertigo

Patients with phobic postural vertigo (PPV) often report a particularly increased unsteadiness when looking at moving visual scenes. Therefore, the differential effects of large-field visual motion stimulation in roll plane on body sway during upright stance were analyzed in 23 patients with PPV, who had been selected for the integrity of their vestibular and balance systems, and in 17 healthy subjects. Visual motion stimulation induced a sensation of apparent body motion (roll vection) in all patients and normal subjects. Normal subjects showed an increased lateral sway path with a lateral shift of the center of pressure (COP) in stimulus direction (mean 1.67 cm, SD 1.63). The patients also exhibited an increase in sway path during visual motion stimulation; however, their body sway differed from that of normals in that there was no lateral displacement of COP (mean 0.19 cm, SD 0.73). The lateral displacement of COP and the increase in RMS of body sway during visual motion stimulation were significantly greater in normals than in the patients ( p<0.05). The patients' increased body sway without COP deviation does not imply an increased risk of falling. Two explanations are conceivable for this increased body sway without body deviation in patients with PPV: (a) the patients rely more on proprioceptive and vestibular rather than on visual cues to regulate upright stance; or (b) they depend on visual, vestibular, and proprioceptive information, but the threshold at which they initiate a compensatory body sway opposite in direction to a perceived body deviation is lower than in normal subjects. The data support the second explanation.

Effect of field size, head motion, and rotational velocity on roll vection and illusory self-tilt in a tumbling room.

The effect of field size, velocity, and visual fixation upon the perception of self-body rotation and tilt was examined in a rotating furnished room. Subjects sat in a stationary chair in the furnished room which could be rotated about the body roll axis. For full-field conditions, complete 360 degrees body rotation (tumbling) was the most common sensation (felt by 80% of subjects). Constant tilt or partial tumbling (less than 360 degrees rotation) occurred more frequently with a small field of view (20 deg). The number of subjects who experienced complete tumbling increased with increases in field of view and room velocity (for velocities between 15 and 30 degrees s-1). The speed of perceived self-rotation relative to room rotation also increased with increasing field of view.

Does intermittence in induced rotary movement have any explanatory significance?

Induced rotary movement has been reported to start and stop repeatedly during 1 min of observation. This has been taken as evidence for the involvement either of cyclorotational optokinetic nystagmus or of roll vection. Both assertions are dubious. Regarding cyclorotational optokinetic nystagmus, available evidence shows that it is too weak to be important in induced rotary movement. Also, induced rotary movement and cyclorotational optokinetic nystagmus are affected differently by the velocity of eliciting stimulation. Regarding roll vection, the conditions for its intermittence do not match those for induced rotary movement. Also, although aftereffects for induced rotary movement are negative, those for roll vection are positive and negative. Intermittence in induced rotary movement may be parsimoniously explained as characteristic of a weak effect.