Feeling ownership of a virtual body in Virtual Reality (VR) enhances the immersion and quality of user experience. Inducing body ownership in VR is mainly based on the Rubber Hand Illusion (RHI) experiment, where watching a rubber hand being stroked while the natural hidden hand is synchronously stroked, induces an illusion of ownership for the rubber hand. Tactile feedback plays a vital role in inducing the RHI in VR. While previous research showed that vibrotactile feedback significantly improves the quality of the illusion, it remains unclear what type of brushing is more effective. In this study, we consider two brushing parameters: (1) self-brushing versus brushing by others and (2) discrete versus continuous brushing. We developed a VR simulation and a haptic sleeve to simulate the RHI through five experimental conditions: control (without haptics), self-discrete, self-continuous, other-discrete, and other-continuous. A total of 85 participants, divided across the 5 experimental conditions, took part in the experiment. The quality of the RHI was assessed using two standard tests, namely proprioceptive drift and an ownership illusion questionnaire. The results indicated that while the control condition (no brushing) showed no significant improvement, all types of brushing resulted in a significant increase in the quality of the illusion. Furthermore, across the four brushing conditions, the self-continuous condition showed a significant increase in the quality of the illusion as compared to the control condition.
A body-penetrating phantom sensation refers to a tactile experience in which the perceived location shifts between the dorsal and ventral sides of the body over time, resulting in the illusion of a tactile stimulus passing through the body. This study explores the integration of auditory and tactile stimuli to enhance the perception of body-penetrating phantom sensations. Combining vibrotactile feedback with various sounds commonly used in gaming, we investigate how multisensory configurations improve their realism, directional clarity, and user satisfaction. The experimental results demonstrate that penetration-related sounds significantly enhance perceived realism and satisfaction. We also compare the changes in emotional pleasantness and arousal levels resulting from integration of sound and tactile stimuli, along with a summary of the subjective responses. Our findings highlight the critical role of semantic harmony between auditory and tactile information, offering actionable insights for improving the realism and immersion of physical interactions in virtual environments.
Individuals who lack tactile and/or proprioceptive sensations in their lower limbs commonly report postural and locomotive imbalance. To mitigate imbalance, haptic feedback has been implemented using devices that employ external sensors and waist-worn actuators for sensory augmentation. Analyses of the effectiveness of these devices have primarily focused on balance outcomes and generally disregard the potential effect of the user's varying activities or anthropometric data on their perception of the haptic feedback. Since motor activity can influence haptic perception, we investigate vibrotactile cue localizability in a waist-worn haptic device for two conditions, standing and walking on a treadmill at a self-selected speed. In this preliminary study, ten participants without sensorimotor deficits wore a waistband equipped with seven vibrotactile actuators. Vibrotactile cues were played at randomized locations during standing and walking, and participants reported the perceived stimulation location. In addition, we recorded relevant anthropometric data for each participant. In both standing and walking conditions, participants correctly localized 51% of the vibrotactile cues on average. When considering zonal accuracy, or localization within one vibrotactor position, participants, on average, achieved an accuracy of 91 % in standing and 90% in walking.
Haptic cues are crucial in the elicitation of emotions, as affective touch research has revealed. However, our increasingly digital lives have eroded access to these cues, having detrimental effects. Thus, the investigation of alternative ways to elicit equivalent emotional responses to those of affective touch merits attention. In the present study, two online experiments examining the emotional responses to sounds of organic affective touch were conducted. In Experiment 1, the emotional responses to a series of organic affective touch sounds, compared to object-based sounds, were evaluated. In Experiment 2, the influence of manipulating the stated nature of the sounds, as either affective touch or object-based, on the emotional responses to the sounds was investigated. The results revealed different patterns in the emotional responses to the affective touch sounds compared to the object-based ones, although participants could not confidently identify affective touch. Furthermore, explicitly stating that the sounds involved object-based interactions increased the evoked valence of two specific object-based sounds. These findings highlight the importance of meaning in affective touch and reveal the high complexity of the sonification of touch. This study paves the way for future research on the emotions of auditory affective touch.
Exploring perceptual dissimilarity spaces of largescale Tactons (i.e., Tactile icons) can inform the design of distinguishable haptic feedback. Yet, collecting pairwise similarity ratings for entire Tacton sets becomes costly as set size increases, prompting the need for alternative methods like subset aggregation. Despite previous efforts, little systematic investigation exists on efficient subset size or participant number needed to estimate large-scale Tacton perceptual spaces within a bounded error threshold. We address this gap by introducing a model that simulates between-subject variability in similarity perception. The model explores various distributions under different conditions, including total Tacton numbers and subset-to-total ratios, to guide user studies. Guided by these simulations, we evaluated subset aggregation with three small-scale Tacton sets (12 or 14 patterns) and one large-scale set (48 patterns). Study 1 revealed that initial simulations underestimated real-world variability. We refined the model, ran simulations for larger-scale conditions, and validated them in subsequent studies. The updated model closely matched reality, showing that designers can use our subset aggregation method to prototype perceptual spaces for large-scale Tacton sets. Notably, 4-7 observations were sufficient to achieve. = 0.6, compared to the typical 12 required for generalization. We discuss the efficacy of subset aggregation and future research directions.
