The plasticity of the interpersonal space in autism spectrum disorder.

In recent years, there has been a dramatic increase in research examining interpersonal space, i.e., the sector of space immediately around the body in which we interact with other people. These studies have consistently revealed impairments of interpersonal space regulation in psychopathological disorders characterized by social disability, such as autism, schizophrenia and social anxiety. The primary goal of this review is to discuss several key points that have emerged in research on interpersonal space regulation in autism spectrum disorders. Particularly, we review recent behavioral evidence revealing that individuals with autism prefer abnormally larger or shorter interpersonal distance than healthy controls, indicating a deficit in regulating the size of interpersonal space (permeability). Then, we focus on how individuals with autism fail to modify their interpersonal space following a brief cooperative interaction with an unfamiliar adult, suggesting a deficit in adapting interpersonal space to the social context (plasticity). Moreover, we discuss evidence indicating that space regulation deficits primarily affect interpersonal (i.e., social), but not peripersonal (i.e., action), space in autism. Finally, we take into consideration the variables influencing interpersonal space plasticity such as person's perspective and severity of social impairment as well as its neural underpinnings. These findings may provide a critical contribution to understanding of the functional mechanisms underlying interpersonal space regulation and its rehabilitation in autism spectrum disorders.