The aim of our group is to develop novel computational tools and methods that allow us to empirically investigate social interactions and collaborative behaviors in the virtual world and in the real world. We base our work on the assumption that similar psychological processes are into play when interacting in the virtual world (e.g. in Multi-User Virtual Reality) and in the real world. Hence, we use Virtual Reality as a research tool to study psychological questions related to social interactions such as joint action coordination, person and body perception, and the transmission of affective states across individuals (e.g. stress and aggression). We are using state-of-the-art computer graphic tools such as personalized, biometric self-avatars, interactive virtual humans, multiuser virtual environments, and real time motion capture and tracking technologies in order to provide most natural and realistic experimental stimuli.