From the above review:
Behind every coalition promise to "get tough on single mothers", behind every Daily Mail story about Britain's "handout culture", or Mitt Romney's notorious comments about "the 47%", there lies an assumption: that being poor is a failure of character. Awkwardly, for those who find this obnoxious, the research sometimes makes it seem true. People who are less well-off really do appear to give in more readily to temptation, making the very purchases they can't afford; to make unwise financial decisions; to use less effective parenting techniques; or to fail to take life-saving drugs, even when they're free. Is this a deep-seated weakness of will, made worse by a "culture of dependency"? The Harvard economist Sendhil Mullainathan and the Princeton psychologist Eldar Shafir reject that idea, and some of the most familiar leftwing responses, too. Poverty, they argue, is indeed a matter of willpower and bad decisions, but the Mail has it back-to-front. It's not that foolish choices make you poor; it's that poverty's effects on the mind lead to bad choices. Living with too little imposes huge psychic costs, reducing our mental bandwidth and distorting our decisionmaking in ways that dig us deeper into a bad situation.