Move or Push? Studying Pseudo-Haptic Perceptions Obtained with Motion or Force Input

Pseudo-haptics techniques are interesting alternatives for generating haptic perceptions, which entails the manipulation of haptic perception through the appropriate alteration of primarily visual feedback in response to body movements. However, the use of pseudo-haptics techniques with a motion-input system can sometimes be limited. This paper investigates a novel approach for extending the potential of pseudo-haptics techniques in virtual reality (VR). The proposed approach utilizes a reaction force from force-input as a substitution of haptic cue for the pseudo-haptic perception. The paper introduced a manipulation method in which the vertical acceleration of the virtual hand is controlled by the extent of push-in of a force sensor. Such a force-input manipulation of a virtual body can not only present pseudo-haptics with less physical spaces and be used by more various users including physically handicapped people, but also can present the reaction force proportional to the user's input to the user. We hypothesized that such a haptic force cue would contribute to the pseudo-haptic perception. Therefore, the paper endeavors to investigate the force-input pseudo-haptic perception in a comparison with the motion-input pseudo-haptics. The paper compared force-input and motion-input manipulation in a point of achievable range and resolution of pseudo-haptic weight. The experimental results suggest that the force-input manipulation successfully extends the range of perceptible pseudo-weight by 80\% in comparison to the motion-input manipulation. On the other hand, it is revealed that the motion-input manipulation has 1 step larger number of distinguishable weight levels and is easier to operate than the force-input manipulation.Comment: This paper is now under review for IEEE Transactions on Visualization and Computer Graphic

Intranasal Chemosensory Lateralization Through the Multi-electrode Transcutaneous Electrical Nasal Bridge Stimulation

Numerous studies have been conducted on display techniques for intranasal chemosensory perception. However, a limited number of studies have focused on the presentation of sensory spatial information. To artificially produce intranasal chemosensory spatial perception, we focused on a technique to induce intranasal chemosensation by transcutaneous electrical stimulation between the nasal bridge and the back of the neck. Whether this technique stimulates the trigeminal nerve or the olfactory nerve remains debatable; if this method stimulates the trigeminal nerve, the differences in the amount of stimulation to the left and right trigeminal branches would evoke lateralization of intranasal chemosensory perception. Therefore, we propose a novel method to lateralize intranasal chemosensation by selectively stimulating the left or right trigeminal nerve branches through the shifting of an electrode on the nasal bridge to the left or right. Finite element simulations reveal that electrical stimulation applied between the electrodes on the left/right nasal bridge and the back of the neck results in the construction of a high current density area on the left/right branch of the trigeminal nerve. The results of two psychophysical experiments reveal that intranasal chemosensation can be lateralized by using the proposed method. The results of our experiment also suggest that lateralization is not the result of electrically induced tactile sensation of the skin surface but rather due to the distribution of stimuli to the trigeminal nerves. To the best of our knowledge, this study is the first successful lateralization of intranasal chemosensation that utilizes an easy-to-apply method without involving nostril blocking

Leveraging Tendon Vibration to Enhance Pseudo-Haptic Perceptions in VR

Pseudo-haptic techniques are used to modify haptic perception by appropriately changing visual feedback to body movements. Based on the knowledge that tendon vibration can affect our somatosensory perception, this paper proposes a method for leveraging tendon vibration to enhance pseudo-haptics during free arm motion. Three experiments were performed to examine the impact of tendon vibration on the range and resolution of pseudo-haptics. The first experiment investigated the effect of tendon vibration on the detection threshold of the discrepancy between visual and physical motion. The results indicated that vibrations applied to the inner tendons of the wrist and elbow increased the threshold, suggesting that tendon vibration can augment the applicable visual motion gain by approximately 13\% without users detecting the visual/physical discrepancy. Furthermore, the results demonstrate that tendon vibration acts as noise on haptic motion cues. The second experiment assessed the impact of tendon vibration on the resolution of pseudo-haptics by determining the just noticeable difference in pseudo-weight perception. The results suggested that the tendon vibration does not largely compromise the resolution of pseudo-haptics. The third experiment evaluated the equivalence between the weight perception triggered by tendon vibration and that by visual motion gain, that is, the point of subjective equality. The results revealed that vibration amplifies the weight perception and its effect was equivalent to that obtained using a gain of 0.64 without vibration, implying that the tendon vibration also functions as an additional haptic cue. Our results provide design guidelines and future work for enhancing pseudo-haptics with tendon vibration.Comment: This paper has been accepted by IEEE TVC

Revisiting the Scheme of Walking-in-Place by Introducing Step-Height Control, Elastic Input and Pseudo-Haptic Feedback

Walking-in-place (WIP) is a locomotion technique that enables users to walk infinitely through vast virtual environments using walking-like gestures within a limited physical space. This paper investigates alternative interaction schemes for WIP, addressing successively the control, input, and output of WIP. First, we introduce a novel height-based control to increase advance speed. Second, we introduce a novel input system for WIP based on elastic and passive strips. Third, we introduce the use of pseudo-haptic feedback as a novel output for WIP meant to alter walking sensations. The results of a series of user studies show that height and frequency based control of WIP can facilitate higher virtual speed with greater efficacy and ease than in frequency-based WIP. Second, using an upward elastic input system can result in a stable virtual speed control, although excessively strong elastic forces may impact the usability and user experience. Finally, using a pseudo-haptic approach can improve the perceived realism of virtual slopes. Taken together, our results promote the investigation and use of alternative interaction WIP schemes in future virtual reality applications.Comment: This paper has been submitted to IEEE TVC

Revisiting Walking-in-Place by Introducing Step-Height Control, Elastic Input, and Pseudo-Haptic Feedback

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The relationship between the body and the environment in the virtual world: The interpupillary distance affects the body size perception.

Previous research suggests that the size of one's body is used as a metric to scale the external world. On the other hand, the influence of information from the external world on the perception of body size is unclear. It has been suggested that increased inter-pupillary distance (IPD) leads people to perceive the external world as smaller than it actually is. The present study investigated the effect of the IPD on body size perception, and the relationship between the perceived scale of the body and the external world when the IPD is manipulated. To this end, in a virtual environment, we manipulated the IPD as well as the size and presence of participants' hands, while participant's eye height was increased vertically. Results showed that, when participants' eye height was increased and their hands were enlarged, people with a fixed IPD perceived the size of their body to be large (like a giant) while the external world was perceived to be changed minimally. Alternatively, people with increased IPD perceived that the external world as having shrank, whereas their perception of their body size changed little. However, when a viewers' virtual hands were not shown, the IPD did not affect the individual's percept of body size, although the IPD did affect one's perception of the external world. These results suggest that, when the ratio of the size between one's body and the external world are explicit, the perceived size of one's body is affected by the IPD or perceived scale of the external world that is affected by the IPD

Leveraging Tendon Vibration to Extend Pseudo-Haptic Sensations in VR

International audienceThe Pseudo-haptic technique is used to modify haptic perception by appropriately changing visual feedback to body movements. Because tendon vibration can affect our somatosensory perception, we propose a method for leveraging tendon vibration to extend pseudo-haptics. To evaluate the proposed method, we conducted three experiments that investigate the effect of tendon vibration on the range and resolution of pseudo-haptic sensation. The first experiment evaluated the effect of tendon vibration on the detection threshold (DT) of visual/physical motion discrepancy. The results show that vibrations on the inner tendons of the wrist and elbow increased the DT. This indicates that tendon vibration can increase applicable visual motion gain without being noticed by users. The second experiment investigated the effect of tendon vibration on the resolution, that is, the just noticeable difference (JND) of pseudo-weight sensation. The results indicate that both with-and without-vibration conditions had a similar JND of pseudo-weight sensation and thus, both conditions can be considered to have a similar resolution of sense of weight. The third experiment investigated the equivalence between the weight sensation induced by tendon vibration and visual motion gain, that is, the point of subjective equality (PSE). The results show that vibration increases the sense of weight, and its effect was the same as that using a gain of 0.64 without vibration. Taken together, our results suggest that using tendon vibration can enable a significantly wider (nearly double) range of pseudo-haptic sensation, without impairing its resolution