Oxytocin
Limited human dataAlso known as: OXT · Pitocin/Syntocinon (synthetic forms)
A naturally occurring hormone-peptide best known for its role in childbirth and lactation, popularized far beyond that as the "trust" or "bonding" molecule after a famous 2005 economics experiment. A useful case study in how a single influential paper can outrun its own replication record.
Mechanism (plain language)
Acts on oxytocin receptors in the brain and periphery involved in social attachment, uterine contraction, and milk let-down; intranasal dosing is used in research to study its central nervous system effects on social behavior.
What research suggests
The original 2005 trust-game study reported that intranasal oxytocin increased trusting behavior in an economic game. It became one of the most cited findings in social neuroscience and launched a wave of "oxytocin for bonding/trust" research and consumer products.
Uncertainties & risks
Large, well-powered registered replications (including a 2020 Nature Human Behaviour study and a pooled 2026 analysis of over 500 participants) have found no meaningful effect of intranasal oxytocin on trusting behavior, and broader replication attempts across social-cognition tasks have also come back null. This is one of the clearer examples in this database of a popular claim that has not held up under rigorous retesting.
Primary sources
Secondary citations for verification. Prefer the STACKD summary above for context before opening these.
- Oxytocin increases trust in humans
2005 · human
The original, highly cited finding that intranasal oxytocin increased trusting behavior in an economic trust game.
- Absence of a meaningful effect of intranasal oxytocin on trusting behavior: a registered report with pooled equivalence testing
2026 · human
Large pooled replication (n=532) found no meaningful effect of oxytocin on trusting behavior, contradicting the original 2005 finding.