Empathy incites a stable prosocial decision bias

Empathy towards suffering individuals serves as potent driver for prosocial behavior. However, it is unclear whether prosocialiaty induced by empathy for another’s pain persists once the other person’s suffering diminishes. To test this, participants underwent functional magnetic resonance imaging (fMRI) while performing a binary social decision task that involved allocation of points to themselves and another. In block one, participants completed the task after witnessing frequent painful stimulation of the other person, and in block two, after observing low frequency of painful stimulation. Drift-diffusion modelling revealed an increased initial bias towards making prosocial decisions in the first block compared to baseline that persisted in the second block. These results were replicated in an independent behavioral study. An additional control study showed that this effect may be specific to empathy as stability was not evident when prosocial decisions were driven by a social norm such as reciprocity. Increased neural activation in dorsomedial prefrontal cortex was linked to empathic concern after witnessing frequent pain and to a general prosocial decision bias after witnessing rare pain. Together, our findings show that empathy for pain elicits a stable inclination towards making prosocial decisions even when that other person’s suffering diminishes.