The sweet side of inequality: how advantageous status modulates empathic response to others' gains and losses.

In the past decade, considerable amounts of studies have explored the neural underpinnings of empathic response toward the positive and negative feelings of others, such as pain and social exclusion, in the field of neuroeconomics. In addition, empathic response of observing other's financial gains and losses have recently started to gain increasing attention in this interdisciplinary field. However, the effects of inequality-averse social preference on individuals' response toward other's gains and losses have not yet been clearly characterized. This work conducted an electrophysiological study with a simple gambling task to explore how inequality aversion matters in modulating neural temporal dynamics toward self and others' gains and losses using scalp-recorded event-related potentials (ERPs). The electrophysiological data demonstrated increased amplitude of P300 toward self's monetary gains and losses independent of advantageous and disadvantageous status. Intriguingly, subjects in the high pay group evoked more pronounced gain loss disparity of feedback-related negativity (FRN) amplitude toward others than themselves. Meanwhile, such a pattern was not observed among the subjects in the low pay group. Therefore, the current double dissociation results of FRN and P300 may indicate that advantageous status enhances subjects' empathic response toward others' pecuniary outcome, giving a direct electrophysiological evidence for the economic modeling on inequality aversion behavior.