Pupil Mimicry Correlates With Trust in In-Group Partners With Dilating Pupils.

Area of Science:

• Psychology
• Social Neuroscience
• Human Behavior

Background:

• Human social interactions involve eye contact and interpreting emotional signals.
• Unique human eye morphology directs attention to pupils, which signal arousal and interest.
• Pupillary changes are involuntary autonomic responses reflecting internal states.

Purpose of the Study:

• To investigate how pupillary changes in a partner affect perceived trustworthiness.
• To examine whether and how humans process their partner's pupillary changes.
• To determine if pupillary mimicry influences trust, particularly within social groups.

Main Methods:

• Participants engaged in incentivized trust games with virtual partners.
• Virtual partners exhibited pupil dilation, static pupils, or pupil constriction.
• Participant pupillary responses and trust decisions were recorded.

Main Results:

• Participants showed increased trust towards partners with dilating pupils and decreased trust towards those with constricting pupils.
• Participants' own pupils mimicked the observed changes in their virtual partners' pupils.
• Dilation mimicry correlated with increased trust specifically for in-group partners.

Conclusions:

• Trust decisions are influenced by observable pupillary changes in interaction partners.
• Pupillary mimicry plays a role in modulating trust, especially within in-group contexts.
• Pupil-contingent trust may be an evolved mechanism related to group living and social bonding.