Induced Self-motion Perception Research Articles

Four-Stroke Apparent Motion Can Effectively Induce Visual Self-Motion Perception: an Examination Using Expanding, Rotating, and Translating Motion.

The current investigation examined whether visual motion without continuous visual displacement could effectively induce self-motion perception (vection). Four-stroke apparent motions (4SAM) were employed in the experiments as visual inducers. The 4SAM pattern contained luminance-defined motion energy equivalent to the real motion pattern, and the participants perceived unidirectional motion according to the motion energy but without displacements (the visual elements flickered on the spot). The experiments revealed that the 4SAM stimulus could effectively induce vection in the horizontal, expanding, or rotational directions, although its strength was significantly weaker than that induced by the real-motion stimulus. This result suggests that visual displacement is not essential, and the luminance-defined motion energy and/or the resulting perceived motion of the visual inducer would be sufficient for inducing visual self-motion perception. Conversely, when the 4SAM and real-motion patterns were presented simultaneously, self-motion perception was mainly determined in accordance with real motion, suggesting that the real-motion stimulus is a predominant determinant of vection. These research outcomes may be worthy of considering the perceptual and neurological mechanisms underlying self-motion perception.

Effects of Visually Induced Self-Motion on Sound Localization Accuracy

The deterioration of sound localization accuracy during a listener’s head/body rotation is independent of the listener’s rotation velocity. However, whether this deterioration occurs only during physical movement in a real environment remains unclear. In this study, we addressed this question by subjecting physically stationary listeners to visually induced self-motion, i.e., vection. Two conditions—one with a visually induced perception of self-motion (vection) and the other without vection (control)—were adopted. Under both conditions, a short noise burst (30 ms) was presented via a loudspeaker in a circular array placed horizontally in front of a listener. The listeners were asked to determine whether the acoustic stimulus was localized relative to their subjective midline. The results showed that in terms of detection thresholds based on the subjective midline, the sound localization accuracy was lower under the vection condition than under the control condition. This indicates that sound localization can be compromised under visually induced self-motion perception. These findings support the idea that self-motion information is crucial for auditory space perception and can potentially enable the design of dynamic binaural displays requiring fewer computational resources.

Effects of Body Orientation Relative to Gravity on Vection in Children and Adults.

We investigated the effects of the interaction between the body and gravitational axes on vection (visually induced self-motion perception) in school-age children and adults. Experiment 1 was a pilot study of adults that was conducted to determine the appropriate experimental settings for the main experiment that included children and adults. The adult participants experienced vection in four different directions in the head-centered coordinate (forward, backward, upward, and downward) under two postural conditions: standing (in which the body and gravitational axes were consistent) and supine (in which the body orientation was orthogonally aligned to the gravitational axis). The adults reported more rapid and longer lasting vection when standing than when supine. In the main experiment (Experiment 2), we tested adults and school-age children under conditions similar to those of Experiment 1 and found that the reported vection was more rapid and longer lasting in children than in adults, whereas the reported vection tended to be more rapid and longer lasting under the standing condition than the supine condition for both age groups. Based on the similarities and differences between children and adults found in the present and previous vection studies, child-specific features of vection are discussed.

Different EEG brain activity in right and left handers during visually induced self-motion perception

Visually induced self-motion perception (vection) relies on visual–vestibular interaction. Imaging studies using vestibular stimulation have revealed a vestibular thalamo-cortical dominance in the right hemisphere in right handers and the left hemisphere in left handers. We investigated if the behavioural characteristics and neural correlates of vection differ between healthy left and right-handed individuals. 64-channel EEG was recorded while 25 right handers and 25 left handers were exposed to vection-compatible roll motion (coherent motion) and a matched, control condition (incoherent motion). Behavioural characteristics, i.e. vection presence, onset latency, duration and subjective strength, were also recorded. The behavioural characteristics of vection did not differ between left and right handers (all p > 0.05). Fast Fourier Transform (FFT) analysis revealed significant decreases in alpha power during vection–compatible roll motion (p < 0.05). The topography of this decrease was handedness-dependent, with left handers showing a left lateralized centro-parietal decrease and right handers showing a bilateral midline centro-parietal decrease. Further time–frequency analysis, time locked to vection onset, revealed a comparable decrease in alpha power around vection onset and a relative increase in alpha power during ongoing vection, for left and right handers. No effects were observed in theta and beta bands. Left and right-handed individuals show vection-related alpha power decreases at different topographical regions, possibly related to the influence of handedness-dependent vestibular dominance in the visual–vestibular interaction that facilitates visual self-motion perception. Despite this difference in where vection-related activity is observed, left and right handers demonstrate comparable perception and underlying alpha band changes during vection.

Material surface properties modulate vection strength.

Realistic appearance and complexity in the visual field are known to affect the strength of vection (visually induced self-motion perception). Although surface properties of materials are, therefore, expected to be visual features that influence vection, to date, the results have been mixed. Here, we used computer graphics to simulate self-motion through rendered 3D tunnels constructed from nine different materials (bark, ceramic, fabric, fur, glass, leather, metal, stone, and wood). There are three ways in which the new stimuli are changed from those found in previous studies: (1) as they move, their appearances interactively change with the 3D structures of the simulated world, as do all the lighting effects and 3D geometric appearances, (2) they are colored, (3) and their components covered a large portion of the visual field. The entire inner surface of each tunnel was composed from one of the nine materials, and optic flow was evoked when an observer virtually moved through the tunnel. Bark, fabric, leather, stone, and wood effectively induced strong vection, whereas, ceramic, glass, fur, and metal did not. Regression analyses suggested that low-level image features such as the lighting and amplitude of spatial frequency were the main factors that modulated vection strength. Additionally, subjective impressions of the nine surface materials showed that the perceived depth, smoothness, and rigidity were related to the perceived vection strength. Overall, our results indicate that surface properties of materials do indeed modulate vection strength.

Perceived Rigidity Significantly Affects Visually Induced Self-Motion Perception (Vection).

When an observer sees a uniformly moving visual stimulus, he or she typically perceives an illusory motion of his or her body in the opposite direction (vection). In this study, the effects of the visual inducer's perceived rigidity were examined using a horizontal sine wave-like line stimulus moving horizontally. Lowering the sine wave amplitude resulted in the perception of a less rigid visual stimulus motion, although the stimulus was always set to move completely rigidly. The psychophysical experiment revealed that visual self-motion perception was weaker in the lower amplitude condition where the visual stimulus was perceived as less rigid. The follow-up experiments showed that the effects of sine wave amplitude manipulation were unrelated to the modulation of the perceived speed. Furthermore, small gaps inserted into the sine waves effectively increased the perceived rigidity and resulted in a strong self-motion perception even in the lower amplitude condition. The current investigation, together with previous studies, clearly demonstrated that perceived features, in addition to the physical ones, play a key role in visual self-motion perception. Visual stimuli, perceived as more rigid, provide a more reliable frame of reference in the observers' spatial orientation, determining their self-motion perception.

An Illusory Contour Can Facilitate Visually Induced Self-Motion Perception.

Uniform motion of a visual stimulus induces an illusory perception of the observer's self-body moving in the opposite direction (vection). The present study investigated whether vertical illusory contours can affect horizontal translational vection using abutting-line stimulus. The stimulus consisted of a number of horizontal line segments that moved horizontally at a constant speed. A group of vertically aligned segments created a 'striped column', while line segments in adjoining columns were shifted vertically to make a slight gap between them. In the illusory contour condition, the end points of the segments within the column were horizontally aligned to generate vertical illusory contours. In the condition with no illusory contour, these end points were not aligned within the column so that the illusory contour was not perceived. In the current study, 11 participants performed this experiment, and it was shown that stronger vection was induced in the illusory contour condition than in the condition with no illusory contour. The results of the current experiment provide novel evidence suggesting that non-luminance-defined visual features have a facilitative effect on visual self-motion perception.

刺激動画像に対するミニチュア効果付与が視覚誘導性自己運動知覚に及ぼす影響( VR心理学5～脳機能計測とVR～)

刺激動画像に対するミニチュア効果付与が視覚誘導性自己運動知覚に及ぼす影響( VR心理学5～脳機能計測とVR～)

CORRIGENDUM to Relative Visual Oscillation Can Facilitate Visually Induced Self-Motion Perception

[This corrects the article DOI: 10.1177/2041669516661903.].

Relative Visual Oscillation Can Facilitate Visually Induced Self-Motion Perception.

Adding simulated viewpoint jitter or oscillation to displays enhances visually induced illusions of self-motion (vection). The cause of this enhancement is yet to be fully understood. Here, we conducted psychophysical experiments to investigate the effects of different types of simulated oscillation on vertical vection. Observers viewed horizontally oscillating and nonoscillating optic flow fields simulating downward self-motion through an aperture. The aperture was visually simulated to be nearer to the observer and was stationary or oscillating in-phase or counter-phase to the direction of background horizontal oscillations of optic flow. Results showed that vection strength was modulated by the oscillation of the aperture relative to the background optic flow. Vertical vection strength increased as the relative oscillatory horizontal motion between the flow and the aperture increased. However, such increases in vection were only generated when the added oscillations were orthogonal to the principal direction of the optic flow pattern, and not when they occurred in the same direction. The oscillation effects observed in this investigation could not be explained by motion adaptation or different (motion parallax based) effects on depth perception. Instead, these results suggest that the oscillation advantage for vection depends on relative visual motion.

Up-down asymmetry in visually induced self-motion perception

Up-down asymmetry in visually induced self-motion perception

Effects of auditory information on self-motion perception during simultaneous presentation of visual shearing motion.

Recent studies have found that self-motion perception induced by simultaneous presentation of visual and auditory motion is facilitated when the directions of visual and auditory motion stimuli are identical. They did not, however, examine possible contributions of auditory motion information for determining direction of self-motion perception. To examine this, a visual stimulus projected on a hemisphere screen and an auditory stimulus presented through headphones were presented separately or simultaneously, depending on experimental conditions. The participant continuously indicated the direction and strength of self-motion during the 130-s experimental trial. When the visual stimulus with a horizontal shearing rotation and the auditory stimulus with a horizontal one-directional rotation were presented simultaneously, the duration and strength of self-motion perceived in the opposite direction of the auditory rotation stimulus were significantly longer and stronger than those perceived in the same direction of the auditory rotation stimulus. However, the auditory stimulus alone could not sufficiently induce self-motion perception, and if it did, its direction was not consistent within each experimental trial. We concluded that auditory motion information can determine perceived direction of self-motion during simultaneous presentation of visual and auditory motion information, at least when visual stimuli moved in opposing directions (around the yaw-axis). We speculate that the contribution of auditory information depends on the plausibility and information balance of visual and auditory information.

Visual blur and motion sickness in an optokinetic drum.

The most commonly cited hypotheses for motion sickness (MS) focus on inconsistent sensory inputs. Visual/vestibular conflicts may lead to MS, but visual input from retinal regions/neural pathways that are sensitive to motion might bear more weight in MS etiology. We hypothesized that inducing blurred vision in an optokinetic drum would attenuate the influence of foveal (parvocellular) input, but not peripheral (magnocellular) input that is sensitive to motion. Increased relative influence of peripheral visual input was predicted to subsequently lead to more visual/vestibular conflict and subsequently more severe MS symptoms. Through goggles that were either clear or frosted, 15 subjects (5 men, 10 women, mean age = 24.9 yr, range = 18-49) viewed the interior of a rotating (60° · s(-1)) optokinetic drum for 10 min. Subjects completed the Simulator Sickness Questionnaire (SSQ) before and after viewing. Overall subjective sickness ratings (0-10) and visually induced self-motion perception (vection) ratings (0-10) were also recorded. Postexposure SSQ scores obtained in the blur condition (total - 52.9, oculomotor - 38.9, disorientation - 69.6) were significantly higher than those obtained in the control condition (total - 30.4, oculomotor - 21.7, disorientation - 37.8). Overall sickness ratings and vection ratings were also significantly higher in the blur condition. These results suggest that visual blur can exacerbate MS, perhaps because of differential influences of visual pathways. Although these results were obtained with an optokinetic drum, possible effects of visual blurring in motion provocative environments such aircraft, watercraft, spacecraft, and land vehicles should be considered.

Optic Flow Induces Nonvisual Self-Motion Aftereffects

There is strong evidence of shared neurophysiological substrates for visual and vestibular processing that likely support our capacity for estimating our own movement through the environment. We examined behavioral consequences of these shared substrates in the form of crossmodal aftereffects. In particular, we examined whether sustained exposure to a visual self-motion stimulus (i.e., optic flow) induces a subsequent bias in nonvisual (i.e., vestibular) self-motion perception in the opposite direction in darkness. Although several previous studies have investigated self-motion aftereffects, none have demonstrated crossmodal transfer, which is the strongest proof that the adapted mechanisms are generalized for self-motion processing. The crossmodal aftereffect was quantified using a motion-nulling procedure in which observers were physically translated on a motion platform to find the movement required to cancel the visually induced aftereffect. Crossmodal transfer was elicited only with the longest-duration visual adaptor (15 s), suggesting that transfer requires sustained vection (i.e., visually induced self-motion perception). Visual-only aftereffects were also measured, but the magnitudes of visual-only and crossmodal aftereffects were not correlated, indicating distinct underlying mechanisms. We propose that crossmodal aftereffects can be understood as an example of contingent or contextual adaptation that arises in response to correlations across signals and functions to reduce these correlations in order to increase coding efficiency. According to this view, crossmodal aftereffects in general (e.g., visual-auditory or visual-tactile) can be explained as accidental manifestations of mechanisms that constantly function to calibrate sensory modalities with each other as well as with the environment.

Walking without optic flow reduces subsequent vection.

This experiment investigated the effect of walking without optic flow on subsequent vection induction and strength. Two groups of participants walked for 5 min (either wearing Ganzfeld goggles or with normal vision) prior to exposure to a vection-inducing stimulus. We then measured the onset latency and strength of vection induced by a radially expanding pattern of optic flow. The results showed that walking without optic flow transiently yielded later vection onsets and reduced vection strength. We propose that walking without optic flow triggered a sensory readjustment, which reduced the ability of optic flow to induce self-motion perception.

Distortion of auditory space during visually induced self-motion in depth.

Perception of self-motion is based on the integration of multiple sensory inputs, in particular from the vestibular and visual systems. Our previous study demonstrated that vestibular linear acceleration information distorted auditory space perception (Teramoto et al., 2012). However, it is unclear whether this phenomenon is contingent on vestibular signals or whether it can be caused by inputs from other sensory modalities involved in self-motion perception. Here, we investigated whether visual linear self-motion information can also alter auditory space perception. Large-field visual motion was presented to induce self-motion perception with constant accelerations (Experiment 1) and a constant velocity (Experiment 2) either in a forward or backward direction. During participants' experience of self-motion, a short noise burst was delivered from one of the loudspeakers aligned parallel to the motion direction along a wall to the left of the listener. Participants indicated from which direction the sound was presented, forward or backward, relative to their coronal (i.e., frontal) plane. Results showed that the sound position aligned with the subjective coronal plane (SCP) was significantly displaced in the direction of self-motion, especially in the backward self-motion condition as compared with a no motion condition. These results suggest that self-motion information, irrespective of its origin, is crucial for auditory space perception.

The Minimum Stimulus Conditions for Vection—Two- and Four-Stroke Apparent Motions Can Induce Self-Motion Perception

Vection can be induced by repeated presentation of static visual images with only two or four frames. The result suggests that vection is only affected by the perceived motion of the visual stimulus, not by awareness of visual displacement.

Effects of Dynamic Luminance Modulation on Visually Induced Self-Motion Perception: Observers' Perception of Illumination is Important in Perceiving Self-Motion

Coherent luminance modulation of visual objects affects visually induced perception of self-motion (vection). The perceptual mechanism underlying the effects of dynamic luminance modulation were investigated with a visual stimulus simulating an external environment illuminated by a moving spotlight (the normal spotlight condition) or an inverted luminance version of it (the inverted luminance condition). Two psychophysical experiments indicated that vection was generally weakened in the inverted luminance condition. The results cannot be fully explained by the undesirable differences of luminosity within the experimental environment, and suggest that the contrast polarity of the visual stimulus has a significant impact on vection. Furthermore, the results show that the dynamic luminance variations weaken vection in the normal spotlight condition in which the observers perceived illumination modulations. In contrast, in the inverted luminance condition, in which the observers cannot perceive the illumination manipulation, the dynamic luminance variations may not impair vection, and may even be expected to strengthen vection, even though they shared similar global and systematic luminance variation with the normal spotlight condition. These experiments suggest that the observer's perception of illumination is a key factor in considering the effects of dynamic luminance modulation of the visual stimulus.

P3-20: Two and Four Stroke Apparent Motions Can Induce Self-Motion Perception

P3-20: Two and Four Stroke Apparent Motions Can Induce Self-Motion Perception

Ventral and dorsal streams processing visual motion perception (FDG-PET study).

BackgroundEarlier functional imaging studies on visually induced self-motion perception (vection) disclosed a bilateral network of activations within primary and secondary visual cortex areas which was combined with signal decreases, i.e., deactivations, in multisensory vestibular cortex areas. This finding led to the concept of a reciprocal inhibitory interaction between the visual and vestibular systems. In order to define areas involved in special aspects of self-motion perception such as intensity and duration of the perceived circular vection (CV) or the amount of head tilt, correlation analyses of the regional cerebral glucose metabolism, rCGM (measured by fluorodeoxyglucose positron-emission tomography, FDG-PET) and these perceptual covariates were performed in 14 healthy volunteers. For analyses of the visual-vestibular interaction, the CV data were compared to a random dot motion stimulation condition (not inducing vection) and a control group at rest (no stimulation at all).ResultsGroup subtraction analyses showed that the visual-vestibular interaction was modified during CV, i.e., the activations within the cerebellar vermis and parieto-occipital areas were enhanced. The correlation analysis between the rCGM and the intensity of visually induced vection, experienced as body tilt, showed a relationship for areas of the multisensory vestibular cortical network (inferior parietal lobule bilaterally, anterior cingulate gyrus), the medial parieto-occipital cortex, the frontal eye fields and the cerebellar vermis. The “earlier” multisensory vestibular areas like the parieto-insular vestibular cortex and the superior temporal gyrus did not appear in the latter analysis. The duration of perceived vection after stimulus stop was positively correlated with rCGM in medial temporal lobe areas bilaterally, which included the (para-)hippocampus, known to be involved in various aspects of memory processing. The amount of head tilt was found to be positively correlated with the rCGM of bilateral basal ganglia regions responsible for the control of motor function of the head.ConclusionsOur data gave further insights into subfunctions within the complex cortical network involved in the processing of visual-vestibular interaction during CV. Specific areas of this cortical network could be attributed to the ventral stream (“what” pathway) responsible for the duration after stimulus stop and to the dorsal stream (“where/how” pathway) responsible for intensity aspects.