Dr Bastian reports in Psychological Science that those who wrote about immoral behaviour exposed themselves to the ice for an average of 86.7 seconds whereas those who had written about everyday experiences exposed themselves for an average of only 64.4.

ECONOMIST: Religion got it right: pain seems to assuage guilt

But there may be an explanation: that the psychological make-up which encourages K-type behaviour worked in the past but is not appropriate to modern circumstances.

ECONOMIST: Why, as people get richer, do they have fewer children?

It provides cognitive behavioural and psychological treatment and support, to eliminate or reduce problematic sexual behaviour in children.

BBC: Young girl sits on a staircase and covers her face.

"His behaviour that night was simply cruel and the lasting psychological harm he has caused is immeasurable, " she said.

BBC: IPad filming rapist Hesam Khosravi's sentence increased

One quibble is that many investigations of genetics and behaviour have relied on participants' retrospective reports of their earlier psychological states, which are often inaccurate.

ECONOMIST: The biology of business: Homo administrans | The