Recent years have witnessed a surge of interest in unravelling the visual mechanisms facilitating our perception of social scenes involving multiple individuals and their interactions. This thesis aims to contribute to this growing field by investigating a frequently overlooked yet essential visual feature of observed social interactions: interpersonal distance, referring to the physical space that separates interactants. Chapter 1 provides an overview of theoretical and empirical contributions to our understanding of person perception. Emphasis is placed on reviewing literature exploring the existence of specialized mechanisms supporting dyadic interaction perception and the pivotal role of interpersonal distance in shaping our evaluations of observed interactions. The first empirical chapter explores biases in our perception of interpersonal distance. Chapter 2 demonstrates susceptibility to the Müller-Lyer illusion, a classic length illusion that has traditionally been studied in domains outside of social perception. These findings highlight the malleability and domain-generality of our representations of interpersonal distance. The remaining empirical chapters test influential claims that dyadic interaction perception engages configural mechanisms akin to face perception. Where observed, configural processing involves heightened sensitivity to changes in spatial arrangements when stimuli are presented in canonical configurations. Chapter 3, using a paradigm where participants detect changes in spatial relations (i.e., interpersonal distance) between pairs of individuals, finds no differences in perceptual sensitivity between conditions manipulating dyad arrangement and orientation, challenging the configural hypothesis. Subsequent chapters investigate individuals with neurodevelopmental conditions known for deficits in face processing. Chapter 4 examines developmental prosopagnosia, while Chapter 5 focuses on autism spectrum disorder. Remarkably, both groups exhibit comparable perceptual sensitivity to their neurotypical counterparts, questioning the extension of face processing deficits to interpersonal distance perception. Chapter 6 summarizes the findings and discusses their implications for understanding the perceptual processes underlying interpersonal distance and the plausibility of the configural account of dyadic interaction perception.