But now researchers have found it improves the social skills of the shy – but has little effect on those who are naturally confident.
The finding could have implications for those with severe social deficiencies, often apparent in conditions like autism.
Researchers at Israel's Seaver Autism Center for Research and Treatment and Columbia University were examining whether the hormone, which occurs naturally in the body could make us more understanding of others.
They conducted a test of 27 healthy adult men, giving them the hormone or a placebo via a nasal spray and then asking them to perform an 'empathic accuracy task' - which measures their powers of reading the thoughts and feelings of others.
This involved watching others discussing emotional moments in their lives, then rating how they felt those people were feeling.