The traditional neoclassical microeconomic theory explains human behaviour by using the "rational choice" model. According to this model, people tend to maximize the difference between expected utility and cost ("expected utility theory"). This theory includes three assumptions: (1) unbounded rationality, (2) unbounded self-interest, and (3) unbounded willpower. Behavioural Economics questions these assumptions and endeavours to render economic analysis more realistic by underpinning it with psychological insights, such as cognitive biases and limited rationality. By means of this psychological foundation, the explanatory power of economic models shall be enhanced.