Honesty may be the best policy, but lying has its merits – even when we are deceiving ourselves. Numerous studies have shown that those who are practised in the art of self-deception might be more successful in the spheres of sport and business. They might even be happier than people who are always true to themselves. But is there ever a downside to believing our own lies?

An ingenious study by Zoe Chance of Yale University tested the idea, by watching what happens when people cheat on tests.

Chance and colleagues ran experiments which involved asking students to answer IQ and general knowledge questions. Half the participants were given a copy of the test paper which had – apparently in error – been printed with the answers listed at the bottom. This meant they had to resist the temptation to check or improve their answers against the real answers as they went along.

Irresistible shortcut



As you'd expect, some of these participants couldn’t help but cheat. Collectively, the group that had access to the answers performed better on the tests than participants who didn't – even though both groups of participants were selected at random from students at the same university, so were, on average, of similar ability. (We can't know for sure who was cheating – probably some of the people who had answers would have got high scores even without the answers – but it means that the average performance in the group was partly down to individual smarts, and partly down to having the answers at hand.)