Virtual reality devices are becoming more and more advanced and affordable in recent times. Especially the usage of those devices in the game industry are recently getting more attention. An important part of all kinds of applications, be it a tutoring application or game, are virtual characters. To ensure an enjoyable and plausible experience the believability of those characters plays a important role. Two factors that have a direct influence on that are verbal and non-verbal social behaviours. Two terms are important when talking about immersive virtual environments, presence and co-presence. Presence represents the feeling of ”being there” and co-presence the sense of ”being there together”. Co-presence can only occur if the virtual environment has a social component. This thesis investigates the influence non-verbal social cues on the sense of presence and co-presence in virtual environments. For that reason a system to enable gaze behaviour for virtual agents was implemented. Besides that, also facial expressions and a simple collision avoidance were realized. This thesis takes a closer look at how those feature were implemented. To evaluate the influence of that implementation a user study was carried out where participants had to test two scenes with different non-verbal agent behaviour. After the test they then had fill out a questionnaire and take part in a final interview. Lastly, the results of that user study are presented and interpreted and future possibilities are getting discussed.
Virtual Reality, Presence, Co-Presence, Believable Agents, Gaze, Collision Avoidance, Facial Expressions