This psychological perspective originated from Freudian psychoanalysis which emphasizes the unconscious components such as conflicts, instinctual energies, etc. Many of Freud's students of psychoanalysis broke off and went their own way, but kept the main aspect of psychoanalysis (the unconscious). As a result, the term psychodynamic is a more general term that incorporates all of these components, but keeps the unconscious as a primary element. The more hard line, scientifically focused psychologists often dismiss this perspective specifically because of the emphasis on the unconscious - their claim is, since you can't observe it, you can't measure it, so how can it be science. You be the judge.