Some lines of evidence have shown that sensory input, especially related to vestibular and somatosensory stimulation, may reduce the symptoms related to simulator sickness and increase the sense of presence in VR. The present study aims at understanding how mechanical vibration and auditory stimulation can be used to improve user experience in the context of VR mediated by head-mounted displays. Four different groups comprising a total of 80 participants were tested under different conditions of sensory input (visual and vibration, visual-auditory, combined visual-auditory and vibratory, and visual only), during a VR roller-coaster experience. No significant differences in simulator sickness were found between the groups exposed to seat vibration and/or audio. However, sense of presence showed to be increased when vibratory stimuli were included. Post-hoc analyses showed that female users but not male ones, experienced an increase of sense of presence when vibratory stimulation was used.

Sense of presence has been often explored in the context of virtual reality (VR) and immersive visual technologies; however, standardized and objective measures of the sense of presence have been difficult to find. Studies attempting to find physiological correlates of sense presence using electroencephalography (EEG) have reported mixed results. In the present study, we used brain event-related potentials (ERPs) elicited by auditory stimuli to identify an objective physiological index of sense of presence during VR, attempting to replicate the findings of previous studies and explain the heterogeneity of results reported in the literature. Participants in our experiment were asked to experience an immersive virtual environment using a modern head-mounted display while passively hearing task-irrelevant frequent standard and infrequent deviant tones as in a classic auditory oddball paradigm. Subsequently, they were asked to complete a battery of questionnaires aimed to estimate their sense of presence during the VR. EEG and questionnaire data from three-seventh participants were analyzed. ERP components evoked by the auditory stimuli were then analyzed. Late ERP components (after 450 ms from stimulus onset) registered over central brain areas were associated with the sense of presence as measured with questionnaires, while earlier components were not associated with presence. The use of different questionnaires and the content of the VR environment may both be a plausible explanation for heterogeneous results as reported in previous studies. The present study showed that late ERP components recorded over the central brain may represent good electrophysiological correlates of the subjective sense of presence.

Virtual reality (VR) is currently being used for a wide range of applications. However, a sense of discomfort during VR experiences (commonly referred to as simulator sickness), is an obstacle for acceptance of the technology outside the niche of tech enthusiasts. Some lines of evidence have shown that sensory input, especially related to vestibular stimulation, may reduce the symptoms related to simulator sickness and increase the sense of presence. This investigation aims at understanding how mechanical vibration can be used to improve user experience in VR, reducing symptoms of simulator sickness and increasing the sense of presence. Four different groups comprising a total of 80 participants were tested under different conditions of sensory input (visual and vibratory, visual and auditory, visuo-auditory and vibratory, and visual only), during a VR roller-coaster experience. A questionnaire was used as the research instrument to evaluate both the sense of presence and the degree of simulator sickness experienced in VR. No significant differences in simulator sickness or presence were found between the groups exposed to seat vibration and/or audio. However, female participants experienced higher sense of presence when vibration was included. For participants experiencing a high degree of simulator sickness, vibration improved the experienced sense of presence, and the inclusion of vibration (but not sound) decreased the level of sickness-related disorientation. The inclusion of multi-sensory stimulation in VR revealed possibilities to improve the experience in some user categories; however, the use of vibration stimulation requires further research to be proven effective for the general public.Keywords: virtual reality, simulator sickness, presence, HMDs, vibration

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Following the advances in modern head-mounted displays, research exploring the human experience of virtual environments has seen a surge in interest. Researchers have examined how to promote individuals’ sense of presence, i.e., their experience of “being” in the VE, as well as to diminish the negative side effects of cybersickness. Studies investigating the relationship between sense of presence and cybersickness have reported heterogeneous results. Authors that found a positive relation have argued that the phenomena have shared cognitive underpinnings. However, recent literature has reported that positive associations can be explained by the confounding factor of immersion. The current study aims to investigate how cybersickness and sense of presence are associated and develop over time. During the experiment, participants were exposed to a virtual roller coaster and presented orally with questions aimed to quantify their perceived sense of presence and cybersickness. The results of the experiment indicate that cybersickness and sense of presence are both modulated by the time spent in the virtual setting. The utilized short measures for sense of presence and cybersickness were found to be reliable alternatives to multi-item questionnaires.