The behavioral approach reorients interest from traits to the behavior of leaders. Leaders' behavior becomes more important than their physical, mental or emotional characteristics. Ohio State University and the University of Michigan developed the two major studies of this approach in the late 1940s and 1950s. Studies have recognized two main behaviors: people-oriented behavior and production-oriented behavior. According to the leader behavioral approach, there are several behaviors that would invariably be effective for leaders, but empirical research does not show a strong relationship between task- or person-oriented leader behaviors and leader effectiveness. A new element has been introduced by the contingency approach approach, which takes into account the impact of the organization or work group on the extent to which certain characteristics and behaviors of the leader will be effective. The approach was mainly used in the late 1960s and 1970s. Fiedler's contingency theory, path-goal theory, Vroom-Yetton-Jago leadership decision-making model, and situational leadership theory are the most popular contingency theories.