Most economic models describe people only in terms of self-interest, without concern for the wellbeing of others. But such behaviour is very rare in reality. Models based on an assumption of self-interest succeed because people really behave in a self-interested way in real economic situations. But in other situations the opposite applies. Experimental findings justify the existence of theories that consider social norms and other motivating factors. Recent decades have also seen the arrival of utility models that include the concept of equity. The study presents the most cogent of these, in which the consideration of equity incorporates consideration of efforts towards equality.