German-American psychoanalyst and one of the first systematic critics of Freud from within the psychoanalytic movement itself. Horney trained in Berlin in the 1910s and 1920s, was among the early members of the Berlin Psychoanalytic Institute, and emigrated to the United States in 1932 — first to Chicago and then, decisively, to New York, where she became a central figure in the Americanization of psychoanalysis along cultural and interpersonal lines.
Her earliest break with orthodoxy concerned the psychology of women. In a series of papers written between 1923 and 1935 — later collected as Feminine Psychology (1967) — Horney challenged Freud's account of female development as constitutively deficient, arguing that what Freud read as biological "penis envy" was in most cases a reaction to social powerlessness, and introducing the complementary concept of male "womb envy" to expose the one-sidedness of the Freudian frame. The papers are among the first serious psychoanalytic contributions to what would later be called feminist theory.
Her mature theoretical work is The Neurotic Personality of Our Time (1937) and Neurosis and Human Growth (1950). Horney replaced the libidinal drive with basic anxiety — the child's felt insecurity in a potentially hostile world — and charted the three characteristic "neurotic trends" by which people cope: moving toward people (compliance), against people (aggression), and away from people (detachment). In the mature work she added her most original concept, the idealized self: the omnipotent, flawless self-image the neurotic constructs to escape the tension between real self and anxious situation, and to whose impossible demands (the "tyranny of the should") the person then becomes enslaved.
Horney was, with Harry Stack Sullivan, Erich Fromm, and Clara Thompson, one of the founders of the William Alanson White Institute — the American center of cultural and interpersonal psychoanalysis — and, later, of the American Institute for Psychoanalysis and the American Journal of Psychoanalysis. Her work prefigured much of later humanistic psychology and a good deal of object-relations theory without being formally part of either school.
Horney is on the graph because her revision of Freud's account of female psychology — against the "penis envy" doctrine, toward a socially shaped account of neurosis — opened the space in psychoanalysis that later feminist theorists occupied.