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
