# From the lab to the real world: emotions serving morality in dyadic negotiation

## TL;DR

This study explores how emotions and brain activity influence moral decisions during real-time negotiations between two people.

## Contribution

The study introduces a naturalistic interpersonal setting with hyperscanning to examine moral negotiation dynamics.

## Key findings

- Dissimilarity in deoxygenated hemoglobin activity between brain hemispheres suggests differentiated cognitive and emotional processing.
- Emotional and social cues play a regulatory role in shaping mutual moral judgments during dyadic negotiation.
- Naturalistic interpersonal interaction enhances ecological validity in studying moral decision-making.

## Abstract

Confronting moral choices in contexts of limited resources requires individuals to integrate reasoning, emotions, and interpersonal dynamics. However, most research on moral decision-making relies on laboratory paradigms that limit ecological validity, restricting natural emotional expression. To address this limitation, this study examined how dyads converge on moral choices through real-time negotiation, focusing on the interplay between cognitive and emotional processing.

Fifteen same-sex adult dyads participated in a moral evaluation task, deciding which of two patients to prioritise for treatment. During the negotiation, conducted in direct social interaction rather than in isolated lab-based evaluation, prefrontal cortex activity was simultaneously recorded in both participants using fNIRS hyperscanning, a paradigm suited to naturalistic interpersonal contexts.

Results revealed a significant increase in the dissimilarity in the deoxygenated haemoglobin (HHb) activity between channel 6 (F6-F4, right hemisphere) and channel 3 (F5-F3, left hemisphere);no significant effects were observed for oxygenated haemoglobin (O2Hb); This, may suggest a differentiated engagement of analytical reasoning (left hemisphere) and emotional–social processing (right hemisphere). The latter – expressed through subtle embodied cues—plays a central regulatory role in influencing each other’s judgment.

These findings support the view that moral negotiation is a dynamic, affectively grounded process, shaped not only by cognitive deliberation but also by emotional information expressed through bodily and facial cues. By integrating hyperscanning with a naturalistic interpersonal setting, this study can contribute to bridging the gap between lab-based and real-world moral decision-making, offering insights into the neural underpinnings of shared evaluation.