Tell lies and the truth can leak out in unexpected ways, says Paul Ekman. He became known in the 1970s for his work on the universality of facial expressions and the emotions behind them. Since then he has been working on ways of recognising deception and other signs of ill-intent, skills that are now being used to identify criminals and potential terrorists. His recent friendship with the Dalai Lama is taking him into uncharted waters - for example, whether it's possible to cultivate goodness in people using "compassion gymnasiums". He spoke to Michael Bond

How good do you think people are at reading emotions in others?

We are generally quite good at recognising emotions in someone who is being perfectly frank. Where we fall down is when people mask or conceal their emotions, and then most people don't know how to decipher the difference between a voluntary and involuntary expression, ...