The psychoanalytic theory of Sigmund Freud (1856- 1939) ; The analytical theory of Carl Jung (1875-1961) ; The individual psychology of Alfred Adler (1870-1937) ; The ego psychological theory of Erik Erikson (1902-1980) ; The radical behaviorism of BF Skinner (1904-1990) ; The moderate behaviourism of Dollard (1900-1980) and Miller (1909- ) ; The need theory of Henry Murray (1893-1988) ; The holistic theory of Gordon Allport (1897-1967) ; The self- actualisation theory of Abraham Maslow (1908-1970) ; The self concept theory of Carl Rogers (1902-1987) ; The personal construct theory of George Kelly (1905-1967) ; The existential theory of Viktor Frankl (1905- ).