Despite the growth of the psychoanalytic movement in the postwar period of the Second World War, prevailed in twentieth-century American psychology a behavioral orientation. However, late 50's and early 60's, some psychologists during the "golden age" of behaviorism were unhappy with the point of view about human nature thereof, and their metodoloía, so institutionally and intellectually rebelled and founded what is known as the "third force" in American psychology, psychoanalysis and behaviorism are the other two forces. His theories collectively called humanísitica psychology