Although researchers have accumulated considerable evidence on the mechanisms of social perception (e.g., what behavioral cues a perceiver uses to draw inferences about other people’s states, traits, intentions, etc.), to date, there is scarcely any research looking at how social perception affects interpersonal behavior. Interpersonal interaction is not a one-way street. It consists of a mutual exchange between at least two interaction partners. Linking social perception to interpersonal behavior is needed because all too often it is tacitly assumed that the way we perceive somebody affects how we act towards that person. But, does it? And if so, how and why? The proposed research program aims at adding interpersonal behavior to existing research on social perception in order to achieve a more sophisticated understanding of how interpersonal interactions and relationships form, develop, and change.Social perception can be subdivided into impression formation and accuracy. The research program proposed here distinguishes between these two aspects and asks how each affects two domains of interpersonal behavior (1) superior-subordinate interaction and (2) physician-patient interaction. Within this framework, 4 specific aims are couched. Aim 1:How does impression formation affect superior-subordinate interaction? Aim2: How does accuracy affect superior-subordinate interaction? Aim 3: How does impression formation affect physician-patient interaction? Aim 4. How does accuracy affect physician-patient interaction? For each of the 4 specific aims, different studies are proposed (total of 7 studies).Most of the research in social perception is correlational meaning that two variables are related but that nothing is known about which one influences the other (causal effect) and that the relation could even be spurious (e.g., explained by a third variable). To gain information about causal relationships, an experimental approach is needed. The proposed research program puts an emphasis on experiments by using a new and innovative technology: Immersive Virtual Environment Technology (IVET).The use of virtual reality (IVET) has distinct advantages for the study of social perception and interpersonal interaction: high experimental control combined with high participant involvement and similarity to real-world social interactions (ecological realism). Additionally, the use of behavioral observation with coding of videotaped verbal and nonverbal behavior is a key element in the proposed research.This research is important because it (1) takes research on social perception a step further by adding a missing link: real-world behavioral implications in the realm of interpersonal interactions and relationships,(2) puts an emphasis on experiments to gain a deeper understanding of causal paths and underlying mechanisms, (3) introduces a new and innovative technology to the field of social perception (IVET), and (4) studies domains of interpersonal interactions that are relevant to everyday social life and therefore have an applied edge to them (superior-subordinate and physician-patient interaction).