Humanistic psychologist Abraham Maslow proposed a hierarchy of needs consisting of physiological needs, safety needs, love and belonging needs, esteem needs, and self-actualization needs. He argued that human motivation is based on seeking to fulfill deficient needs, and that self-actualization involves using one's talents to their fullest potential. Maslow studied self-actualized individuals to understand positive human development and potential. While influential, Maslow's theories have been criticized for lacking empirical evidence and reflecting his own values.