Karen Horney was a German psychoanalyst who practiced in the United States during her later career. Her theories questioned some traditional Freudian views. This was particularly true of her theories of sexuality and of the instinct orientation of psychoanalysis. She is credited with founding feminist psychology in response to Freud's theory of penis envy. She disagreed with Freud about inherent differences in the psychology of men and women, and like Adler, she traced such differences to society and culture rather than biology.

Sigmund Freud was an Austrian neurologist and the founder of psychoanalysis, a clinical method for evaluating and treating pathologies seen as originating from conflicts in the psyche, through dialogue between patient and psychoanalyst, and the distinctive theory of mind and human agency derived from it.