'Theory X' and 'Theory Y' are theories of human motivation and management. They were created and developed by Douglas McGregor at the MIT Sloan School of Management in the 1960s. These theories describe two contrasting models of workforce motivation applied by managers in human resource management, organizational behavior, organizational communication and organizational development. According to the models, the two opposing sets of general assumptions of how workers are motivated form the basis for two different managerial styles. Theory X stresses the importance of strict supervision, external rewards, and penalties: in contrast, Theory Y highlights the motivating role of job satisfaction and encourages workers to approach tasks without direct supervision.