Picture this: One day while drinking your morning coffee, you are reminded of a friend from your past. You have not spoken to this person in some time, but you remember them fondly and wonder how they are doing. You pick up your phone and start typing a message to say “hello!” only to delete the message before hitting send. Has something like this ever happened to you? If so, you are not alone.

Past research in our lab found that up to 90 per cent of people report having an “old friend” — a friend they care about but with whom they have lost touch. And while most people say they would like to reconnect with an old friend, only about 30 per cent are willing to send a message, even with favourable circumstances, such as when the relationship did not end on bad terms, people think their friend wants to hear from them or people have their old friend’s contact information.

This reluctance to reach out to old friends is puzzling because a large body of research demonstrates that social relationships are a strong predictor of health and happiness. Indeed, having a larger and more diverse social network is associated with greater well-being.