# Behavioural Realism and Its Impact on Virtual Reality Social Interactions Involving Self-Disclosure
## 1 Introduction
### The Present Study  
The reviewed literature demonstrates the utility of motion capture for enhancing the behavioural realism of avatars. Studies like [PERSON] et al. [11] and [PERSON] et al. [37] emphasise the importance of body gestures for enhancing social interactions, while others, including [PERSON] and [PERSON] [18] and [PERSON] et al. [29], highlight the importance of facial gestures. Regarding the potential use of avatars for therapy conducted in VR, self-disclosure studies by [PERSON] et al. [23] and [PERSON] et al. [22] suggest that VR social interaction platforms may offer an alternative to face-to-face therapy for individuals who prefer to interact with an avatar that has a level of behavioural realism that is comfortable for them.  
The current study investigates different levels of behavioural realism by comparing two types of avatars: the commercially available Vive Sync avatar that has limited motion tracking of the face and body and an iClone avatar used in the UNREAL Engine with full-body motion tracking of both the face and body that was used in prior research studies [22; 23]. This comparison allowed us to investigate the effects of different motion-tracking methods on the avatar's perceived realism and enjoyment of the interaction. It also extends previous research by incorporating both participant disclosure and interviewer disclosure, allowing us to investigate the role of reciprocal sharing during VR social interactions.  
The primary aim of this research was to examine the ratings of perceived realism, enjoyment, and eye contact across the iClone UNREAL and Vive Sync avatars. Specifically, this study investigated whether high behavioural realism afforded through full-body motion capture is necessary for improving perceptions of realism and enjoyment in VR social interactions involving self-disclosure. Many studies have concluded that higher levels of behavioural realism can foster positive social interactions in VR by increasing likability, trust, enjoyability, and social presence [3; 22; 24; 26; 29; 37; 43].  
For the first hypothesis, it was expected that an avatar with a higher level of behavioural realism provided with full-body motion tracking would be rated as more realistic than an avatar with limited motion tracking. For the second hypothesis, it was expected that an avatar with a higher level of behavioural realism would be rated as more enjoyable when compared to an avatar with limited behavioural realism. This is because a realistic avatar with precise motion tracking should avoid the uncanny valley and provide a lifelike experience that a less realistic avatar cannot [52; 59; 61; 76]. For the third hypothesis, it was expected that the avatar with full facial tracking would result in higher user ratings of perceived eye gaze duration compared to the avatar using the Vive Sync headset with partial facial tracking. This is because the avatar with full facial tracking will have more nonverbal cues for the participant to engage with and focus on [29; 35; 40; 41; 42; 43].  
The secondary aim of this research addresses a limitation identified in both [PERSON] et al. [23] and [PERSON] et al. [22], where only the participants disclosed personal experiences. To address this limitation, a reciprocal social interaction where both the participant and avatar disclose negative and positive experiences was implemented to clarify if the source of disclosure could influence perceptions of realism. Thus, it was expected that disclosures from the avatar would result in higher realism ratings. This is because the participants' attention will be directed towards the avatar rather than to themselves.