[2] His younger brother, Milton, later known by the stage name Michael Kidd, became an acclaimed choreographer and occasional actor on Broadway and in Hollywood movies.
However, Greenwald chafed at the long periods of quiet listening required in Freudian psychoanalysis, so he developed direct decision therapy.
His dissertation, published in 1958 as The Call Girl: A Social and Analytic Study, humanized the women and explored the reasons for their career choice.
[1] Greenwald's research found that prostitutes utilized defense mechanisms to cope with their profession, which included masochism, and denying to themselves that they were having sex.
It was adapted into the 1960 film Girl of the Night, starring Anne Francis and featuring Lloyd Nolan as psychotherapist.
He became a distinguished professor at the United States International University, and served as president of the Academy of Psychologists in Marital and Family Therapy.