Many of us think we are harder working, more intelligent and better drivers than the average person. We also think we are morally superior. A 2014 study found that even convicted prisoners thought they were morally better — not just than the average prisoner but than the average person outside.

The study, at a prison in the south of England, asked inmates to rate themselves against the average prisoner and the average member of the community for traits such as morality, kindness, honesty, self-control and being law-abiding.

Although the convicts were serving sentences for violence, robbery, drug offences and burglary, they rated themselves as virtuous. Only on one trait did they think they were not superior to the average non-prisoner: being law-abiding. They felt they and people outside were equally law-abiding.