Expectancy theory proposes that individuals are motivated when they believe good performance will result in an desirable outcome. The theory is based on three variables: valence, expectancy, and instrumentality. Valence refers to how much value or importance a person places on a potential outcome. Expectancy is a person's belief that their efforts will lead to good performance. Instrumentality is the belief that good performance will result in the desired outcome. According to the theory, motivation is highest when valence, expectancy, and instrumentality are all high. Additional factors like ability, skills and support from others also impact performance beyond just motivation.