Research is hard. While this is generally true of all science, psychology in particular is vulnerable, as it's a very, very new field still under heavy development. Only recently has psychology emerged as a mature science with robust theories, and supposed "facts" of the past are still in popular culture despite being debunked. Writers fail to recognize this, and the supposed professionals in their stories will quote woefully out-of-date representations of Sigmund Freud's theory of the unconscious, Carl Jung's collective unconscious archetypes, or Abraham Maslow's hierarchy of needs. This is the equivalent of a modern physicist discussing luminiferous aether, or a biologist believing Lamarck Was Right.