Odour enhances the sense of presence in a virtual reality environment.

Virtual reality (VR) headsets provide immersive audio-visual experiences for users, but usually neglect to provide olfactory cues that can provide additional information about our environment in the real world. This paper examines whether the introduction of smells into the VR environment enhances users' experience, including their sense of presence through collection of both psychological and physiological measures. Using precise odour administration with an olfactometer, study participants were exposed to smells while they were immersed in the popular PlayStation VR game "Resident Evil 7". A within-subject study design was undertaken where participants (n = 22) walked-through the same VR environment twice, with or without the introduction of associated congruent odour stimuli. Directly after each gameplay, participants completed a questionnaire to determine their sense of presence from the overall gameplay and their sense of immersion in each of the virtual scenes. Additionally, physiological measurements (heart rate, body temperature and skin electrodermal activity) were collected from participants (n = 11) for each gameplay. The results showed the addition of odours significantly increased participants' sense of spatial presence in the VR environment compared to VR with no odour. Participants also rated the realism of VR experience with odour higher compared to no odour, however odour addition did not result in change in emotional state of participants (arousal, pleasure, dominance). Further, the participants' physiological responses were impacted by the addition of odour. Odour mediated physiological changes were dependent on whether the VR environment was novel, as the effect of odour on physiological response was lost when participants experienced the aroma on the second gameplay. Overall, the results indicate the addition of odours to a VR environment had a significant effect on both the psychological and physiological experience showing the addition of smell enhanced the VR environment. The incorporation of odours to VR environments presents an opportunity to create a more immersive experience to increase a person's presence within a VR environment. In addition to gaming, the results have broader applications for virtual training environments and virtual reality exposure therapy.

A school-based fluoride mouth rinsing programme in Sarawak: a 3-year field study.

BACKGROUND: This study was undertaken to assess the impact of fluoride mouth rinsing on caries experience in a cohort of schoolchildren 3 years after implementation. METHODS: 270 children aged 8-9 years from four schools in Sarawak were selected at baseline. Baseline data was collected to ensure that the selected schools did not differ significantly. Children from two schools rinsed with 0.2% sodium fluoride under supervision, while those from the other schools did not. RESULTS: After 3 years, 242 schoolchildren remained in the study. At the end of the study, the mean DMFT for the test group was 2.3 (95% CI, 1.93-2.67) while the mean DMFT for the control group was 4.01 (95% CI, 3.39-4.63). The mean DMFS for the test group was 3.40 (95% CI, 2.68-4.12) while the mean DMFS for the control group was 6.67 (95% CI, 5.47-7.87). After 3 years, 24.2% of those in the test group remained caries free compared to 11.5% in the control group. The risk of developing caries decreased 0.52 times among the children from the 'test' group exposed to the fluoride mouth rinsing programme as compared to the unexposed 'control' group (RR = 0.48, 95% CI, 0.26-0.85). DISCUSSION AND CONCLUSION: The findings show that a school-based weekly 0.2% sodium fluoride mouth rinsing programme is an effective caries preventive measure and should be implemented in fluoride-deficient areas as a means of reducing the prevalence of dental caries in these communities.