Modelling interpersonal discomfort ratings in third-person settings: An exploratory study

"Personal" and "peripersonal" spaces are two concepts describing the space close to the body. Intrusion of others into the personal space, provokes a feeling of discomfort; responses to objects situated within peripersonal space are facilitated. Facilitation of responses within peripersonal space typically follow a sigmoid trend, with a sharp increase around a central point, that is defined as its boundary. We explored if intrusion into personal space makes such a steep transition in discomfort and whether the distance of this transition is related to personality traits. A computerized discomfort judgement task was administered to 45 participants. Each trial presented two full-height human silhouettes facing each other on a screen, separated by simulated distances from 200 to 16 cm, based on an assumed silhouette height of 175 cm. The order of presentation of 12 interpersonal distances, from longest to shortest, created an impression of approach. For each trial, participants imaged themselves as one of the two silhouettes and rated their discomfort. The individual response medians for each distance were approximated using sigmoid, linear or power law functions. The central points of inflection for individual sigmoid functions were calculated and correlated with participants' scores for social anxiety, the Big Five Inventory, and motor (dis)coordination. Discomfort ratings increased as the simulated distance between silhouettes decreased. The obtained sequences of rating medians were approximated more efficiently with sigmoid compared to linear or power law functions in 38 participants. More distant central points can be associated with higher social anxiety, dyspraxia and neuroticism, and lower agreeableness. The sigmoid shape of discomfort changes indeed mirrors that of peripersonal space boundaries, but this resemblance remains speculative and requires further investigation to clarify whether common mechanisms are involved. Discomfort judgments based on internal subjective feelings may serve as a quantitative proxy for personal distance limits.