‘Close to Me’: neural empathic reactions are reduced by physical distance and barriers between the observer and someone in pain

Empathy towards others’ pain might be shaped by the social and affective relationships between individuals, such that, for instance, neural empathic reactions are magnified for affectively close others when compared to strangers. In line with the recent evidence that the same parietal area is involved in the processing of both physical and psychological distance, we hypothesized that empathy may be modulated as a function of the physical distance between the observer and someone in pain. We conducted 2 event-related potentials (ERPs) experiments. In Exp. 1, we tracked neural activity in a standard pain decision task in which, in a between-subjects design, participants had to decide whether each presented face was painfully or neutrally stimulated. One group of participants was exposed to faces perceived as further (3 m), while another group of participants was exposed to faces perceived as closer (2 m). We observed a modulation of the neural empathic reaction as a function of the distance manipulation, such that the reaction was larger for the faces perceived as closer. Although intriguing, it is still to be understood the underlying mechanism through which manipulating the physical distance may interfere with empathic responses. One of such possible mechanism may refer to the notion of ‘embodied simulation’ and ‘interaction space’, the shared reaching space of two individuals. Within this framework, the sharing of emotions and affective states might be sensitive to the physical distance separating the two individuals. The goal of Exp. 2 (2a: further faces; 2b: closer faces) was to investigate whether interfering on the ‘interaction space’ per se could modulate neural empathic reactions. Participants performed the same task as in Exp. 1 under both one standard condition, in which they seated directly in front of the screen (no-plexiglass condition), and a second critical condition in which a transparent plexiglass was interposed between them and the screen (plexiglass condition). We expected a reduced empathic reaction in the plexiglass condition for participants exposed to the faces perceived as closer (Exp. 2b), as a result of interference with the participants' interaction space. Results revealed a reduced empathic response at both fronto-central and centro-parietal electrodes, for faces stimuli perceived at a closer distance (Exp. 2b) in the plexiglass condition. The manipulation of the ‘interaction space’ did not impact the empathic responses toward faces perceived as further (Exp. 2a).