We examined the relationship between the degree of sense of immersion (one aspect of our human personality) and visually induced self-motion perception (vection). A psychological experiment using radially expanding patterns that induced self-motion perception was conducted, followed by an assessment of the sense of immersion. The participants rated the level of general applicability by answering simple four questions. Also they rated their level of immersion to vection by answering other 18 simple questions. We found that vection strength correlated positively with the degree of the sense of immersion but not with the level of immersion to vection itself.

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In visual psychophysics, a CRT monitor has been widely used to present visual stimuli, while its temporal resolution was limited by its frame length of about 5 ms (i.e., refresh rate of 200 Hz). Recently, however, a high speed DLP projector was introduced to the market, which realizes much shorter frame length (〜 0.2 ms) for binary images. For such projectors, moreover, the duty ratio of the optical images can be manipulated, which makes it possible to investigate the mechanism of human temporal visual processing which cannot be accessed with the conventional visual devices. In this paper, we explain some temporal properties of the projector essential to the psychophysical experiments and show an example of experimental setup made in combination of the projector with a programming library for psychophysical experiments.

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We developed a walking recording and experiencing system. For the recording system we captured stereo motion images from two cameras attached to a person's forehead with synchronized data of ankles' accelerations. For the experiencing system we presented 3-D motion images with binocular disparity on a head-mounted display, and presented vibrations to user's soles of feet at the same time. The vibration was made from a footstep sound when a person walked. We found that users subjectively reported that the 3-D motion images with synchronized foot vibrations elicited stronger feelings of walking, leg motion, stepping, and telepresence than without vibrations. These results suggest that our walking experiencing system gives users somewhat active walking feelings.

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We compared the strength of self-motion perception (vection) with and without a decoy who reported very strong or very weak vection. When the decoy reported strong vection, participants reported stronger vection than they did when the decoy reported weak vection. To the best of our knowledge, this is the first report demonstrating that vection perception can be altered by conformity to decoys.

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We measured vection strength induced by six different colors in an optic flow stimulus. Vection strength was measured by using button pressing and via magnitude estimation. Vection strength was inhibited by multiple colored dots but not by uniform grey dots. Even with brighter background, this inhibition effect was obtained. This result might be related to the fact that stimuli that are 'too colorful' are not a realistic representation of the external world.

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Recently, we can very easily and frequently find vection scenes in Japanese movies and animation films. However there had not been a database for them. Our purpose of this study was to make a database of vection scenes in Japanese movies and animations and provide VR psychologists all over the world with that database. We checked many movies and animations and found 30 vection scenes. We uploaded that information on our web site (senotake.jp). We also conducted a psychological experiment to assess vection strength obtained by those scenes and compared them to perceived vection obtained by a normal and simple vection stimulus (the standard stimulus) that had been used in our previous vection experiments. The results showed that perceived vection induced by those scenes were nearly the same strength as that of vection induced by the standard stimulus. We also revealed some effective and inefficient techniques of scene presentations in this study. Finally we calculated various image statistics and compared them to vection strength. That analysis revealed that a scene that contained more changes could induce stronger vection. We sincerely hope that this study can be the bridge between experimental psychologists and contents creators and developers.

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The present study investigated how somatosensory stimuli influence auditory distance perception, by manipulating spatial and temporal consistency between these stimuli. Auditory stimuli were presented in participants' rear space through a dynamic binaural virtual auditory display, while somatosensory stimuli were presented via small electric fans (i.e., air current stimuli). Participants performed an auditory distance discrimination task. Results showed that auditory distance discriminability was decreased when the somatosensory and auditory stimuli occurred at the same time but different azimuthal angles. In contrast, the discriminability was maintained when both stimuli occurred at the same azimuthal angle. These results suggest the contribution of somatosensory cues to auditory distance perception.

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For users in a shared virtual environment (VE), a sense of being there together (copresence) is a key to behave as if they are in an actual environment. The present study investigated whether copresence can be measured using the social Simon effect (SSE) and event-related potentials (ERPs) associated with this effect. In the standard Simon effect, single participants press a left or right key in response to target color, while the target appeared on the left or right side of a monitor. Responses are generally faster when the target and key are located on the spatially-congruent side than on the incongruent side. This less happens when participants responds only to either color with either key. However, this effect reemerges when a participant responds to either color with either key, and their partner sat side by side responds to the other color with the other key. This is called SSE. We hypothesized that the SSE should occur if users experience copresence in the VE. Experiment 1 replicated the SSE in the actual environment. In Experiments 2 and 3, two participants in different rooms observed the same virtual environment with their partners' avatar through head-mounted displays, and performed the task. We compared between a group in which the participants interacted with their partner beforehand in the VE (high copresence group) and that in which they did not (low copresence group). The results showed that the stronger SSE occurred for the former group, suggesting that the SSE can be a measure for copresence in the VE.

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To construct secure augmented reality (AR), it is important to clarify the relationship between visual attention and stimuli in 3D environments. We used object substitution masking (OSM) which is a phenomenon that depends on attentional transition. In this study, a target and masking dots appeared on different depth planes. The results suggested that OSM disappeared when the target was presented 50cm farther than the mask under using split monitor viewing. However, the resulting OSM was not affected by the depth differences under stereoscopic viewing. These results suggest that appropriate depth differences between visual information can preserve visibility in AR environments.

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In this study, we examined whether the activation of the mirror neuron system is influenced by the spatial accuracy of sound field reproduction using an auditory virtual reality system. In the experiment, we measured the brain activity during listening to action-related and nonaction-related sounds with electroencephalography using mu rhythm suppression as an index of motor cortical activation. Also, we set three sound reproduction conditions: 'spatialized (valid)', 'non-spatialiezed (invalid)' and 'monaural' conditions. In both spatialized and non-spatialized condition, the sound stimuli were presented through 96-ch. loud speakers. The results showed that the mu-suppression for action-related sounds was significantly larger in the spatialized sound conditions than the non-spatialized and the monaural conditions, and suggested that the mirror neuron activation was influenced by the spatial accuracy of sound field reproduction. These results suggest the possibilities to use mirror neuron activation as an objective measure for 'plausibility illusion' of virtual reality systems.

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The ideal AR x-ray vision should enable users to clearly observe and grasp not only occludees, but also occluders. In this paper, we report a first evidence for the validity of a vergence-based selective rendering both occludee and occluder layers with dynamic opacity in AR x-ray vision. Using the gaze depth as a trigger to select the layers has an essential advantage over using other gestures or voice commands in the sense of avoiding collision between user's intentional selection and unintentional actions. Experiments with a visual paired-comparison task shows that the proposed method has achieved a 20% higher success rate, and reduced 30% of the average task completion time than a non-selective method using a constant and half transparency. The results prove the feasibility of vergence-based AR x-ray vision.

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In this paper, the authors introduce recently found visual effects; based on them, they make considerations on several problems in 3D image display. Especially, focused on volume perception with binocular viewing and from motion, they considered the causes producing the card board cut-out phenomena and fattening effects in image; then gave the potential method to reduce them.

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In this paper, we investigated to control a phantom sensation by visual stimuli. A phantom sensation is one of tactile illusion caused by vibration stimuli. Some previous works employed vibration motors for a tactile display, and utilized a phantom sensation to present tactile stimuli in a large area with a few vibration motors. Our research is to control tactile perception by visual stimuli. Our previous works showed that visual stimuli influence tactile perception. From the results, we considered that it is also possible to control a phantom sensation by visual stimuli. We made a primitive visual-tactile display, and conducted some experiments. The results showed that visual stimuli influenced a phantom sensation and it seemed to be possible to cause or not to cause a phantom sensation by visual stimuli.

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Latency, measured from the user's motion to the display output, causes virtual reality cybersickness and decreases task performance. However, the effect of small delay has not been investigated sufficiently. Therefore the purpose of this study was to reveal the effect of a small latency on the subjects. The subjects were asked to stand on the force plate with one foot so that the length of body sway can be measured with several lags ranging from 1 ms to 66 ms. The experiments showed that 1) the sway increased linearly as the latency got longer 2) the HMD with latency of 1 ms also degraded the sense of balance compared to the naked eye with the same limited field of view (FOV) as in HMD, and 3) the difference between the virtual and real worlds' content had an effect on the result of the experiment. From these results, user's stability can be regarded as the direct index of the quality of VR system for the user.

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The main contribution of this paper is establishing the method to enhance work efficiency unconsciously by controlling the time rate that a virtual clock shows. Recently, it has been revealed that work efficiency is influenced by various environmental factors such as work environment's atmosphere, temperature and so on. On the contrary, it has become clear that the work rate is affected by a time sensation. While working, the more amount of information we process in a limited time, the longer elapsed time we perceive. Besides, the higher cognitive load we get from difficult works, the longer elapsed time we perceive. In this way, a perception of time rate and a cognitive load of works affect each other. In this study, we focus on a "clock" as a tool, which gives the recognition of time rate and length for everyone mutually. We propose a method to improve a person's work efficiency, especially work rate unconsciously by giving an illusion of false sense of the passaged time by a virtual clock that displays the time rate that differ from real one visually. We conducted experiments to investigate the influence of the changes in the displayed virtual time rate on time perception and work efficiency. Besides, to evaluate an effect of an implication of a "clock", we conducted the counter experiments with a flicker stimulus and a reversely rotated virtual clock. The experimental results showed that by displaying the accelerated time rate, it is possible to improve work efficiency with constant time perception, and a "clock" is critical for enhancing work rate.

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The effects of moods and emotions on correlations with direction methods for stereoscopic 3D images are the focus of this study. Specifically, we investigated the sense of fear in different 2D and 3D conditions as well as the different directing methods involved. Directional techniques were sorted into three categories according to the dynamic characteristics of the focus object in 3D space along the Z-Axis, XY-Axis, and Fixed-Axis directions. The emotional value of fear was characterized in terms of two values, valence and arousal, which were measured using the Self-Assessment Manikin (SAM) and skin potential reaction (SPR). The results indicated considerable differences in terms of viewing condition, directing method, and gender. SAM measurements indicated low valence and high arousal scores in 3D viewing condition. Furthermore, the effects of directing methods depended on the center and range of 3D space. Depth representation was a more important factor for female than male subjects. The SPR frequency increased during viewing Z-Axis direction in 3D condition.

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The latency is a fundamental and important value in the specification of HMD. However, the HMDs of the state of the art equipped with the latency compensation, the notion of the simple lag is not enough to describe the dynamical characteristic of them. The purpose of this study is to evaluate the average latency as the equivalent simple lag and the accuracy of compensation by the experiment. Further, the dynamical distortion caused by the lag compensation is also evaluated.Oculus Rift DK2 is chosen as the target HMD of this evaluation. The average latency was approximately 26 ms without lag compensation, and it was about 1 ms with both of the Prediction and the Timewarp.

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We examined proprioceptive drift in the situation where an image of a hand was presented at the position slightly displaced from a participant's real occluded hand. When motion of the image hand was presented synchronized with that of the real hand, the drift was nearly same as the displacement of the visual position of the image hand irrespective of the congruence of depth position of the image and real hand. The drift persisted at least for 20 seconds. These results suggest that when the visual position of virtual body is shifted from the real position in a VR system, an observer may experience constant proprioceptive drift of their own body.

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We have introduced a novel stereoscopic display method that combines the human perceptual feature known as slit viewing and the light ray reproduction 3-D presentation in SIGGRAPH 2014. In this method, several one-dimensional light arrays are arranged in a row with certain spatial intervals, and each light array rotates fast, changing its flashing pattern. Accordingly, different moving images are shown to the left and right eyes, which can lead to 3-D stereoscopic presentation of moving images. However, a serious drawback in exploiting this method for a visual information display is that a three-dimensional image cannot be viewed on the near side of the arrays. We overcame this drawback by using perceptual transparency.

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Novel view synthesis (NVS) is renowned for its variety of applications, and recent techniques are based on an image-based approach, which uses multiple input images to synthesize novel views, with the help of 3D geometry. View-dependent texture mapping is one of the most well-known techniques of this kind. However, it sometimes suffers from blurry or duplicated edges when the geometry is inaccurate because it blends several input images for alleviating inconsistent lighting conditions among input images. This paper presents a view-dependent texture mapping-based method for NVS that leverages geometry-aware color continuity in texture selection. Our color continuity constraint suppresses noticeable texture boundaries in resulting novel views without blending, while our method relaxes the constraint on steep geometric changes. Since such geometric changes are often followed by surface property changes, our new color continuity constraint can lead to more natural novel views. We formulate our texture selection by an energy minimization problem and solve it with the graph cut algorithm. Our experimental results have demonstrated the superiority of our method.

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We propose a real-time heat transfer simulation method which visualize heat behavior in virtual cooking interactively. Our method is a combination of finite element heat transfer simulation and rigid body dynamics simulation. We achieved to reproduce temperature changes on the surface of both a beef and an iron plate as cookware. Proposed simulator also targets changes of boundary condition; e.g.between the air and solid objects or solid objects and solid objects. The rigid body dynamics simulation calculates the collision between solid objects. An experimental implementation showed the computation speed is high enough for cookery with a multi-thread computation. We aim that our method will be useful for cooking technique practice, cookery prediction and cookery game.

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This paper clarifies effect of the synchronous angular speed of a Steerable dummy head in direction judgment of horizontal sound source. We conducted direction judgment experiments using dynamic binaural signals recorded with a Steerable dummy head of which synchronous rotation angular speed was modified by 0.1, 0.5, -0.5 and -1.0 of a listener's head rotation angular speed. The mean direction judgment performances of 4 listeners, who had served as listeners for sound localization experiments using dynamic binaural signal recorded by a Steerable dummy head, tests were over 70% for any synchronous speed modification rates. The performances are significantly better than that of the head-still condition. This result suggests that an accurate head tracking is not necessarily required for the dynamic binaural sound reproduction system.

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"GRP Contract Form" is a contract form which aims to realize the act of "Open Sharing" and to increase the effect of its use for joint research and development project in the field like media art or interaction design. "Open Sharing" in this paper means publishing achievements in order to be used by third parties freely within a certain range. In this paper, overall developing process of this project will be discussed along with following contents, such as design guideline of contract's template, its overview and updates, GRP Contract Form as an achievement, and user practice and evaluation after "Open Sharing" on GitHub.

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We created a new vection stimulus, which we presented to participants with Google Cardboard and via a portable terminal based on the Android operating system. This method is quite new, very affordable, and highly portable. It thus has high potential for bringing in a new age of vection research. The new stimulus can be modified as observers move their heads and bodies; we conducted an experiment comparing it to the standard stimulus that cannot be changed in this manner. Results showed that vection can be stronger with the new stimulus, but facilitation effects were obtained both in our new stimulus and the old stimulus when there were their head and body movements. We discuss the possible reasons for this result.

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PVLC (Pixel-level Visible Light Communication) is a method that can embed human-imperceptible metadata in projected images with high-speed flickering. A significant advantage of the method is that no displacement or offset problems occur without a separate position measurement step. However, previous projection systems utilize PVLC can update neither invisible data nor visible images in real time due to its technical limitation. To solve this problem, we propose RPVLC (Reconfigurable Pixel-level Visible Light Communication) system that can update the data and the images dynamically, reconfigure the trade-off between image frame rate and image resolution, and control full color LED light source. In this paper, RPVLC system design, method, implementation, and its performance evaluations are detailed.

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