Hildegard Peplau was an American nurse who developed the theory of interpersonal relations in nursing. She received her BA in interpersonal psychology in 1943 and her MA in psychiatric nursing in 1947. Peplau's conceptual model incorporated concepts from Freud, Maslow, and Miller and integrated psychoanalytical, social learning, human motivational, and personality development theories. Her model included four components: orientation, identification, exploitation, and resolution.