Abraham Maslow
Abraham Maslow developed the theory of human motivation now known as Maslow's Hierarchy of Needs. A psychologist, Maslow noted that some human needs were more powerful than others. He divided those needs into five general categories, from most urgent to most advanced: physiological, safety, belonging/love, esteem, and self-actualization. Maslow first published his theory in the 1940s, and it became a widely accepted notion in the fields of psychology and anthropology. Maslow was a professor at Brandeis University from 1951 until 1969; his major texts included Motivation and Personality (1954) and Toward a Psychology of Being (1962).
Related figures: behavioral psychologist B.F. Skinner, psychedelic psychologist Timothy Leary, and psychiatric heavyweights Carl Jung and Sigmund Freud.