Fehr-Schmidt inequality aversion constrains vmPFC value coding in social context: A computational fMRI study

Area of Science:

• Neuroscience
• Cognitive Science
• Social Psychology

Background:

• The ventromedial prefrontal cortex (vmPFC) is implicated in subjective value encoding.
• Its role in individual differences in fairness preferences, particularly concerning ingroup vs. outgroup dynamics, is not fully understood.

Purpose of the Study:

• To investigate whether the vmPFC tracks individual differences in fairness preferences.
• To examine how inequality aversion parameters modulate vmPFC activity during social decision-making in the Ultimatum Game.

Main Methods:

• Utilized computational modeling to estimate individual inequality aversion (α) from behavioral data.
• Applied fMRI analysis to an openly available dataset of participants playing the Ultimatum Game against computer, ingroup, and outgroup peers.
• Extracted vmPFC activation using a coordinate-based region of interest analysis.

Main Results:

• Offer size predicted vmPFC activation, supporting its role in value coding.
• Individual inequality aversion (α) moderated vmPFC responses to ingroup offers, with higher aversion linked to weaker vmPFC signals.
• No significant difference in this modulation was found between ingroup and outgroup offers, nor in the ventral striatum.

Conclusions:

• vmPFC value signals are associated with individual fairness preferences within an ingroup context.
• This association is modulated by inequality aversion, particularly for ingroup interactions.
• Findings contribute to understanding group-modulated fairness processing and the neural basis of social decision-making.