In virtual reality exposure therapy (VRET) for anxiety disorders, sense of presence in the virtual environment is considered the principal mechanism that enables anxiety to be felt. Existing studies on the relation between sense of presence and level of anxiety, however, have yielded mixed results on the correlation between the two. In this meta-analysis, we reviewed publications on VRET for anxiety that included self-reported presence and anxiety. The comprehensive search of the literature identified 33 publications with a total of 1196 participants. The correlation between self-reported sense of presence and anxiety was extracted and meta-analyzed. Potential moderators such as technology characteristics, sample characteristics including age, gender and clinical status, disorder characteristics and study design characteristics such as measurements were also examined. The random effects analysis showed a medium effect size for the correlation between sense of presence and anxiety (r = .28; 95% CI: 0.18–0.38). Moderation analyses revealed that the effect size of the correlation differed across different anxiety disorders, with a large effect size for fear of animals (r = .50; 95% CI: 0.30–0.66) and a no to small effect size for social anxiety disorder (r = .001; 95% CI: −0.19–0.19). Further, the correlation between anxiety and presence was stronger in studies with participants who met criteria for an anxiety disorder than in studies with a non-clinical population. Trackers with six degrees of freedom and displays with a larger field of view resulted in higher effect sizes, compared to trackers with three degrees of freedom and displays with a smaller field of view. In addition, no difference in effect size was found for the type of presence measurement and the type of anxiety measurement. This meta-analysis confirms the positive relation between sense of presence and anxiety and demonstrates that this relation can be affected by various moderating factors.

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In this study, we addressed the effect of stereoscopy on presence, anxiety, and cybersickness in a virtual public speaking world, and investigated the relationships between these three variables. Our results question the practical relevance of applying stereoscopy in head-mounted displays (HMDs) for virtual reality exposure therapy (VRET) in a virtual public speaking world. In VRET, feelings of presence improve the efficacy (B. K. Wiederhold & M. D. Wiederhold, 2005). There are reports of a relatively large group of dropouts during VRET at low levels of presence in the virtual environment (Krijn, Emmelkamp, Olafsson, & Biemond, 2004). Therefore, generating an adequate level of presence is essential for the success of VRET. In this study, 86 participants were recruited and they were immersed in the virtual public speaking world twice: once with stereoscopic rendering and once without stereoscopic rendering. The results showed that spatial presence was significantly improved by adding stereoscopy, but no difference for reported involvement or realism was found. The heart rate measurements also showed no difference between stereoscopic and nonstereoscopic viewing. Participants reported similar anxiety feelings about their talk and similar level of cybersickness in both viewing modes. Even though spatial presence was significantly improved, the size of statistical effect was relatively small. Our results therefore suggest that stereoscopic rendering may not be of practical importance for VRET in public speaking settings.

BackgroundPatients who receive rehabilitation after hip replacement surgery are shown to have increased muscle strength and better functional performance. However, traditional physiotherapy is often tedious and leads to poor adherence. Exercise games, provide ways for increasing the engagement of elderly patients and increase the uptake of rehabilitation exercises.ObjectiveThe objective of this study was to evaluate Fietsgame (Dutch for cycling game), which translates existing rehabilitation exercises into fun exercise games. The system connects exercise games with a patient’s personal record and a therapist interface by an Internet of Things server. Thus, both the patient and physiotherapist can monitor the patient’s medical status.MethodsThis paper describes a pilot study that evaluates the usability of the Fietsgame. The study was conducted in a rehabilitation center with 9 participants, including 2 physiotherapists and 7 patients. The patients were asked to play 6 exercise games, each lasting about 5 min, under the guidance of a physiotherapist. The mean age of the patients was 74.57 years (standard deviation [SD] 8.28); all the patients were in the recovery process after hip surgery. Surveys were developed to quantitatively measure the usability factors, including presence, enjoyment, pain, exertion, and technology acceptance. Comments on advantages and suggested improvements of our game system provided by the physiotherapists and patients were summarized and their implications were discussed.ResultsThe results showed that after successfully playing the games, 75% to 100% of the patients experienced high levels of enjoyment in all the games except the squats game. Patients reported the highest level of exertion in squats when compared with other exercise games. Lunges resulted in the highest dropout rate (43%) due to interference with the Kinect v2 from support chairs. All the patients (100%) found the game system useful and easy to use, felt that it would be a useful tool in their further rehabilitation, and expressed that they would like to use the game in the future. The therapists indicated that the exercise games highly meet the criteria of motor rehabilitation, and they intend to continue using the game as part of their rehabilitation treatment of patients. Comments from the patients and physiotherapists suggest that real-time corrective feedback when patients perform the exercises wrongly and a more personalized user interface with options for increasing or decreasing cognitive load are needed.ConclusionsThe results suggest that Fietsgame can be used as an alternative tool to traditional motor rehabilitation for patients with hip surgery. Lunges and squats are found to be more beneficial for patients who have relatively better balance skills. A follow-up randomized controlled study will be conducted to test the effectiveness of the Fietsgame to investigate how motivating it is over a longer period of time.

To test whether synthetic emotions expressed by a virtual human elicit positive or negative emotions in a human conversation partner and affect satisfaction towards the conversation, an experiment was conducted where the emotions of a virtual human were manipulated during both the listening and speaking phase of the dialogue. Twenty-four participants were recruited and were asked to have a real conversation with the virtual human on six different topics. For each topic the virtual human's emotions in the listening and speaking phase were different, including positive, neutral and negative emotions. The results support our hypotheses that (1) negative compared to positive synthetic emotions expressed by a virtual human can elicit a more negative emotional state in a human conversation partner, (2) synthetic emotions expressed in the speaking phase have more impact on a human conversation partner than emotions expressed in the listening phase, (3) humans with less speaking confidence also experience a conversation with a virtual human as less positive, and (4) random positive or negative emotions of a virtual human have a negative effect on the satisfaction with the conversation. These findings have practical implications for the treatment of social anxiety as they allow therapists to control the anxiety evoking stimuli, i.e. the expressed emotion of a virtual human in a virtual reality exposure environment of a simulated conversation. In addition, these findings may be useful to other virtual applications that include conversations with a virtual human.