Neural evidence for inequality-averse social preferences

Area of Science:

• Neuroscience
• Social Psychology
• Behavioral Economics

Background:

• Social science theories propose humans dislike outcome inequality due to negative impacts on experienced reward.
• Behavioral and anthropological evidence supports inequality aversion, but direct neural evidence is lacking.
• Alternative explanations like social image or reciprocity can account for inequality-disliking behaviors.

Purpose of the Study:

• To directly test for neural evidence of inequality-averse social preferences.
• To investigate the brain's response to monetary inequality using functional magnetic resonance imaging (fMRI).

Main Methods:

• Functional MRI (fMRI) was used to measure neural responses in reward-related brain regions.
• Participants were paired, with one receiving a larger monetary endowment to create inequality.
• Neural activity was recorded as participants evaluated monetary transfers to themselves and the other participant.

Main Results:

• Activity in the ventral striatum and ventromedial prefrontal cortex differed based on participants' pay status.
• High-pay subjects showed greater neural response to transfers to others than to self.
• Low-pay subjects exhibited the opposite pattern, responding more to transfers to self.

Conclusions:

• The findings provide direct neural evidence supporting inequality-averse models of social preferences.
• The brain's reward circuitry is demonstrably sensitive to both advantageous and disadvantageous inequality.
• This study elucidates the neural basis of social preferences concerning economic disparities.