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Maslow's (1943, 1954) hierarchy of needs is a motivational theory in psychology comprising a five tier model of human needs, often depicted as hierarchical levels within a pyramid. Maslow stated that people are motivated to achieve certain needs and that some needs take precedence over others.
Maslow's work lead to additional attempts to develop a grand theory of motivation, a theory that would put all of the factors influencing motivation into one model. An example is provided by Leonard, Beauvais, and Scholl (1999).