"Surrounded, detached": the relationship between defensive peripersonal space and personality

Abstract

Introduction: Personality shapes the cognitive, affective, and behavioral interactions between individuals and the environment. Defensive peripersonal space (DPPS) is the projected interface between the body and the world with a protective function for the body. Previous studies suggest that DPPS displays inter-individual variability that is associated with psychiatric symptoms, such as anxiety. However, DPPS may share a link with personality traits.

Methods: Fifty-five healthy participants were assessed with the Personality Inventory for DSM-5 (PID-5)-Adult to evaluate personality dimensions. Subjects underwent the Hand Blink Reflex (HBR) task that estimates the DPPS limits by assessing the modulation of blink intensity in response to the median nerve stimulation. Data of the HBR was analyzed with Bayesian multilevel models, while the relationship between DPPS and personality traits was explored using network analysis.

Results: HBR was best modeled using a piecewise linear regression model, with two distinct slope parameters for electromyographic data. Network analyzes showed a positive correlation between the proximal slope and detachment personality trait, suggesting that individuals with higher scores in the detachment trait had an increased modulation of HBR, resulting in a larger extension of the DPPS.

Discussion: Features of the detachment personality trait include avoidance of interpersonal experiences, restricted affectivity, and suspiciousness, which affect interpersonal functioning. We suggest that DPPS may represent a characteristic feature of maladaptive personality traits, thus constitute a biomarker or a target for rehabilitative interventions.

Keywords: Hand Blink Reflex; PID-5; embodied cognition; individual difference factors; network analysis.

Figure 1

Group-average, rectified HBR waveforms recorded from Orbicularis Oculi muscles (OO) and averaged for left and right eyes when the arm was placed in the three stimulation positions: FAR (blue), MIDDLE (red) and NEAR (green). The target positions are illustrated in the upper right corner, showing the location of the static arm when the electrical stimulations were provided (corresponding to time = 0). Area under curves (AUC–mV*ms) were computed for each position. In the lower panel are represented different HBR estimated models of fit from the Bayesian analysis starting from a “null” intercept-only model to a more complex exponential model with three model estimates parameters: intercept, multiplicative and exponential parameter.

Figure 2

Network of the associations between personality traits and DPPS extension. The thickness of edges reflects the magnitude of the correlation. Green lines represent positive correlations, red lines represent negative ones–legend of the strength of association is reported on the top-right of the figure. Green nodes represent personality measures, derived from PID–5, blue nodes represent parameters derived from the piecewise linear model of HBR data. NA: indicates Negative Affectivity; DIS indicates Disinhibition; DET indicates Detachment; ANT indicates Antagonism; FtoM indicates the slope calculated between HBR response obtained in far and middle position; MtoN indicates slope calculated between HBR response obtained in middle and near; intercept indicates values assumed by the variable when FtoM and MtoN values have mean of 0.