Do people always act rationally and in their own best interests? Thaler and Sunstein do not believe so. They are convinced that psychological factors often stop people from making the best decisions. Their 2008 work argues that governments should 'nudge' citizens to make better choices in all sorts of areas, from eating habits, to health, to financial planning. They also argue, however, that such interventions must not restrict freedom of choice, since 'nudges' can have a significant effect on people's conduct. Nudge has made a huge impact, with both the American and British governments incorporating its approach and ideas into policy.