Is waving back at a stranger on a bridge a sign of happiness? © Getty Images

Is waving back at a stranger on a bridge a sign of happiness?

Waving is a behaviour that promotes bonding within a group, but is responding to someone waving at you a sign of your state of mood?

Asked by: Nick Wilthew, Newport Pagnell


Waving back is a sort of ‘affiliative behaviour’, something that promotes bonding between members of a group. Experimentally, it’s seen more in pleasant, non-urban environments: such studies implicate mood, although they don’t assess happiness directly. From the other side, several studies have manipulated mood to investigate social interaction, although I couldn’t find any specifically looking at mood and affiliative behaviour. So it’s a great research suggestion! I would expect to see a correlation, if only because unhappy or depressed people often avoid social contact. What’s more, people usually seek ‘mood congruent’ activities: they’re drawn to cheerful things when happy, to sad ones when unhappy. Happiness even causes people to evaluate social interactions in a positive light. But you should bear in mind that experimental subjects also seek ‘mood incongruent’ stimulation before meeting strangers, probably to moderate their mood (‘cool’ is usually more socially acceptable). Also, your basic personality will probably be much more influential: some people may always wave back, others never.


Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.