“Mind the plexiglass” - An invisible barrier is enough to reduce neural empathic responses to pain and touch

Empathy might be shaped by socio-affective relationships between individuals, such that neural empathic reactions are magnified for affectively close others compared to strangers. In a recent investigation, we demonstrated that the perceived physical distance between actors could shape people’s empathic reactions towards a person in pain. However, the underlying mechanism through which manipulating the physical distance may interfere with empathic responses it is still to be understood. One such possible mechanism refers to the notion of ‘interaction space’, the shared reaching space of two individuals. Within this framework, the sharing of affective states might be sensitive to the physical distance between individuals. This study aimed investigating, by using the ERP technique, whether the neural empathic reactions for observed faces, either gently touched or painfully stimulated, perceived within the interaction space could be modulated by the presence of a transparent physical barrier, which prevents the possibility to interact with the partner, without altering neither the quality nor the low-level characteristic of the observed stimuli. We designed an ERP study in which participants were exposed to faces stimulated by either a needle or a Q-tip under both one condition in which they directly seated 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 to observe a moderating effect on ERP empathic reactions as a function of the presence of the barrier, such that when participants were under “plexiglass condition”, they would show a lower magnitude of the neural empathic reactions. Further, given the plexiglass prevents the possibility of reaching the other person, we hypothesized that the plexiglass barrier would have impacted on the empathic reactions, regardless of the type of stimulation observed. Results confirmed our hypothesis showing that the presence of a physical barrier decreased the ERP amplitude, suggesting a reduction of the observer’s neural emphatic reaction.