How interpersonal distance varies throughout the lifespan.

Interpersonal Distance (IPD) is defined as the physical distance that individuals maintain between themselves and others during social interactions. While literature has extensively focused on this everyday social behavior, how IPD changes throughout the lifespan remains an open question. In this study, 864 participants, aged 3-89 years, performed the Stop Distance Paradigm in their real-life environments, and we measured the distance they kept from both familiar and unfamiliar others during social interactions. We found that IPD not only differs based on the identity of the other person (familiar versus unfamiliar) but critically declines as a function of age, following two distinct non-linear trends for familiar and unfamiliar others. Moreover, behavioral variability also undergoes a lifetime development, with IPD becoming more stable as age increases. Overall, the present study suggests that IPD is a complex and acquired behavior that changes throughout the lifespan and varies according to individual and situational variables.