Inconsistent Locomotion Inhibits Vection

Hot Wind to the Body Can Facilitate Vection Only When Participants Walk Through a Fire Corridor Virtually

Vection has been reported to be enhanced by wind, as long as the wind is a normal temperature and not hot. However, here we report that a hot wind can facilitate vection, as long as it is natural and consistent with the visual stimulus. We created a fire-corridor stimulus that was consistent with a hot wind and a control stimulus composed of cubes, which were irrelevant to a hot wind. We compared the vection strength induced by a fire-corridor (fire condition) visual stimulus with that induced by geometric cubes (no-fire condition) visual stimulus. There were three wind type conditions: a normal temperature wind, hot wind, and no wind. The results showed that a normal temperature wind facilitated vection and that a hot wind (but not a normal wind) highly enhanced vection when a fire-corridor stimulus was presented. These results suggest that vection is highly affected and modulated by high-level cognitive processes.

Virtual Walking Sensation by Prerecorded Oscillating Optic Flow and Synchronous Foot Vibration

This article reports the first psychological evidence that the combination of oscillating optic flow and synchronous foot vibration evokes a walking sensation. In this study, we first captured a walker's first-person-view scenes with footstep timings. Participants observed the naturally oscillating scenes on a head-mounted display with vibrations on their feet and rated walking-related sensations using a Visual Analogue Scale. They perceived stronger sensations of self-motion, walking, leg action, and telepresence from the oscillating visual flow with foot vibrations than with randomized-timing vibrations or without vibrations. The artificial delay of foot vibrations with respect to the scenes diminished the walking-related sensations. These results suggest that the oscillating visual scenes and synchronous foot vibrations are effective for creating virtual walking sensations.

Future challenges for vection research: definitions, functional significance, measures, and neural bases

This paper discusses four major challenges facing modern vection research. Challenge 1 (Defining Vection) outlines the different ways that vection has been defined in the literature and discusses their theoretical and experimental ramifications. The term vection is most often used to refer to visual illusions of self-motion induced in stationary observers (by moving, or simulating the motion of, the surrounding environment). However, vection is increasingly being used to also refer to non-visual illusions of self-motion, visually mediated self-motion perceptions, and even general subjective experiences (i.e., “feelings”) of self-motion. The common thread in all of these definitions is the conscious subjective experience of self-motion. Thus, Challenge 2 (Significance of Vection) tackles the crucial issue of whether such conscious experiences actually serve functional roles during self-motion (e.g., in terms of controlling or guiding the self-motion). After more than 100 years of vection research there has been surprisingly little investigation into its functional significance. Challenge 3 (Vection Measures) discusses the difficulties with existing subjective self-report measures of vection (particularly in the context of contemporary research), and proposes several more objective measures of vection based on recent empirical findings. Finally, Challenge 4 (Neural Basis) reviews the recent neuroimaging literature examining the neural basis of vection and discusses the hurdles still facing these investigations.

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.

Stronger vection in junior high school children than in adults

Previous studies have shown that even elementary school-aged children (7 and 11 years old) experience visually induced perception of illusory self-motion (vection) (Lepecq et al., 1995, Perception, 24, 435–449) and that children of a similar age (mean age = 9.2 years) experience more rapid and stronger vection than do adults (Shirai et al., 2012, Perception, 41, 1399–1402). These findings imply that although elementary school-aged children experience vection, this ability is subject to further development. To examine the subsequent development of vection, we compared junior high school students' (N = 11, mean age = 14.4 years) and adults' (N = 10, mean age = 22.2 years) experiences of vection. Junior high school students reported significantly stronger vection than did adults, suggesting that the perceptual experience of junior high school students differs from that of adults with regard to vection and that this ability undergoes gradual changes over a relatively long period of development.

Vection in depth during treadmill walking

Vection has typically been induced in stationary observers (ie conditions providing visual-only information about self-motion). Two recent studies have examined vection during active treadmill walking--one reported that treadmill walking in the same direction as the visually simulated self-motion impaired vection (Onimaru et al, 2010 Journal of Vision 10(7):860), the other reported that it enhanced vection (Seno et al, 2011 Perception 40 747-750; Seno et al, 2011 Attention, Perception, & Psychophysics 73 1467-1476). Our study expands on these earlier investigations of vection during observer active movement. In experiment 1 we presented radially expanding optic flow and compared the vection produced in stationary observers with that produced during walking forward on a treadmill at a 'matched' speed. Experiment 2 compared the vection induced by forward treadmill walking while viewing expanding or contracting optic flow with that induced by viewing playbacks of these same displays while stationary. In both experiments subjects' tracked head movements were either incorporated into the self-motion displays (as simulated viewpoint jitter) or simply ignored. We found that treadmill walking always reduced vection (compared with stationary viewing conditions) and that simulated viewpoint jitter always increased vection (compared with constant velocity displays). These findings suggest that while consistent visual-vestibular information about self-acceleration increases vection, biomechanical self-motion information reduces this experience (irrespective of whether it is consistent or not with the visual input).

I speak fast when I move fast: the speed of illusory self-motion (vection) modulates the speed of utterances

Speed of utterance is an important factor in smooth and efficient conversation. We report a technique to increase utterance speed and that might improve a speaker's impression and information efficiency in conversation. We used a visual display consisting of optic flows in a large visual field that induced participants' illusory self-motion perception (vection). The speed of vection corresponded to the speed of the optic flows. Using this method, we investigated whether vection speed affects utterance speed. We presented fast- and slow-moving optic flow stimuli while dynamically swapping random dots presented to participants, during which time the participants were asked to talk for 2 min. Results revealed that the utterance speed was significantly faster in the fast optic flow condition. Our method could be a stepping stone for establishing a technique of modulating speech speed effectively.

Wearing Heavy Iron Clogs Can Inhibit Vection

Visually induced illusory self-motion perception is termed vection. We measured vection strength in participants wearing either wooden or iron clogs together with or without a weight-jacket (four conditions). We hypothesized that the heavier items would inhibit vection more because they make locomotion difficult. Results partially showed that the iron clogs could inhibit vection. We concluded that cognition of the fact that the heavier iron clogs made locomotion difficult might function as an inhibitor of vection, suggesting that cognition can alter vection strength.

Second-order motion is less efficient at modulating vection strength

Visually induced illusions of self-motion (vection) are often induced using constant velocity optic flow. However, adding simulated viewpoint jitter and oscillation to these displayscan significantly improve the vection experience (especially when this jitter/oscillation is orthogonal to the constant flow component - Nakamura, 2010; Palmisano et al., 2008). In the present experiment, we found that vection was only facilitated when luminance-, but not contrast-, defined vertical oscillatory motion was added to the constant horizontal display motion (even though observers clearly reported seeing both the oscillatory and constant display motions in both conditions). These findings demonstrate that the vection enhancement provided by simulated viewpoint oscillation is not simply based on the perceived display motion.

Healin' groovy: movement affects the appearance of the healing grid illusion

Vection alters the perception of a visual illusion. It enhances the illusory completion of the healing grid (Kanai, 2005, Best Illusion of the Year Contest, Vision Sciences Society). When we perceive our self-motion, the mode of vision is different from that of when we are stationary.

Perceptually Plausible Sounds Facilitate Visually Induced Self-Motion Perception (Vection)

We examined whether and how sounds influence visually induced illusory self-motion (vection). Visual stimuli were presented for 40 s. They were made radially, expanding or contracting visual motion field and luminance-defined gratings drifting in a vertical or horizontal direction. Auditory stimuli were presented with the visual stimuli in most conditions; we employed sounds that increased or decreased in intensity, or ascended or descended in frequency. As a result, the sound which increased in intensity facilitated forward vection, and the sound which ascended/descended in frequency facilitated upward/downward vection. The perceptual plausibility of the sound for the corresponding self-motion seemed an important factor of enhancing vection.

Consistent Air Flow to the Face Facilitates Vection

We examined whether a somatosensory cue suggesting forward self-motion facilitated vection. We provided a consistent air flow to subjects' faces by using an electric fan. Vection strength was increased when the air flow was provided.