Obesity – and its related illnesses – endangers the lives of millions across the world. While healthier, more physically active lifestyles can mitigate this, the question remains of how policymakers can get people to switch from being couch potatoes to keen runner beans. This column presents new evidence suggesting that for many even a nudge may suffice.

At a time when many people are asking themselves what to give their friends and family for Christmas, this column asks why we bother to give anything at all. In the economic laboratory, subjects exhibit significant levels of altruistic giving and aversion to unfairness. Outside the laboratory however, we encounter vast amounts of poverty and inequality and yet only give a tiny fraction of our income to charity.

Why do people persistently make seemingly irrational decisions? This column introduces neuroeconomic theory, which uses neuroscience and neurobiology to try to shed light on the black box of human decision-making.

Have capital market booms and crashes discredited the efficient market hypothesis? This column says yes and suggests a new model that explains asset pricing in terms of a battle between fair value and momentum driven by principal-agent issues. Investment agents’ rational profit seeking gives rise to mispricing and volatility.

Greedy bankers are getting most of the blame for the current financial crisis. This column explains bankers did behave badly for mainly three reasons. They committed cognitive errors involving biases towards their own prior beliefs; too many male bankers high on testosterone took too much risk, and a flawed compensation structure rewarded perceived short-term competency rather than long-run results.