Guilt, so some people have suggested, is what makes us nice. When we do someone a favour or choose not to exploit someone vulnerable, we do it because we fear the guilt we'd feel otherwise. A team of neuroscientists, psychologists and economists have this month produced some new results in this area, using a model from psychological game theory.

Researchers have unveiled the first prototypes of robots that can develop emotions and express them too. If you treat these robots well, they'll form an attachment to you, looking for hugs when they feel sad and responding to reassuring strokes when they are distressed. But how do you get emotions into machines that only understand the language of maths?
Game theorists model the evolution of trust and trustworthiness
Intuitive number sense linked to formal mathematics ability
Is geometry hard-wired into our brain?
Mathematicians in search of romantic success
The search for the maths gene
Do you need language to do maths?