In psychology, the concept of the locus of control was first described by Julian Rotter in 1954. This concept developed out of his generalized expectancy hypothesis, which suggests that a behavior is controlled by a person’s expectation of what will most likely happen as a result. As part of his social learning theory, Rotter emphasizes the connection between behavior and one's personal, subjective experience of past outcomes.
Individuals who have a highly internal locus of control tend to believe that they have a high degree of control over what happens in their lives. For example, a person who has a locus of control that is highly internal may believe that their good health is due to a healthy diet and exercise, or that winning a game is due to skill and effort. These individuals tend to see the good and bad things that happen to themselves and others as a result of their own actions or lack of action.
Individuals who have a locus of control that is primarily external tend to believe that the events in their lives are controlled by external factors like luck, fate, others’ behavior or “powerful others.” For example, a person with a high degree of external locus of control might believe that their good health is due to genetics or environmental factors, or that winning a game is largely due to lucky events. These individuals tend to see the good and bad things that happen to them and others as being controlled by factors outside of their control.
Rotter was quick to assert that locus of control cannot be simply stated as either/or, and is not unchangeable. Individuals may generally fall closer to one end or the other of the locus of control spectrum, but in specific situations they may attribute an outcome to the opposite end of the spectrum. Likewise, an individual’s locus of control may change over time.