Alfred Hitchcock adapted Psycho from a story by author Robert Bloch, who had modeled the character of Norman Bates after Ed Gein, who is suspected to have killed his victims between 1954 and 1957. In the asphyxiation death of his brother Henry (who was verbally critical of their neurotic-controlling mother) in 1944, though the supposedly harmless young Gein was quickly dismissed as a suspect, it's believed that he was guilty of that crime too. Other characters very loosely based on Gein are Buffalo Bill in "The Silence of the Lambs" (1991) and Thomas Hewitt in "The Texas Chainsaw Massacre" (1974). The main similarities to Gein that appear in "Psycho" include the feminine qualities of Norman Bates and the disturbingly strong attachment to the cruel domineering mother.
The film somewhat stirred controversy when it was released because it was the first time that a leading actress' (Janet Leigh) character dies during the first third of the film. Before Psycho, the leading actress' character either lives throughout the film or dies at the end. Her character never dies early in the film.
In the opening scene, Marion Crane is wearing a white bra because Alfred Hitchcock wanted to show her as being "angelic." After she has taken the money, the following scene has her in a black bra because now she has done something wrong and evil. Similarly, before Marion steals the money, she has a white purse; after she's stolen the money, her purse is black.
There are many references to birds in this film, few examples are: Marion's surname is Crane which is a bird, the movie is set in Phoenix which is a legendary bird which rose from the ashes, there are stuffed birds in Norman Bates' parlour and his hobby is stuffing them, there are numerous pictures of birds through out the hotel, and Norman makes many references to birds such as telling Marion she "eats like a bird." Hitchcock was fascinated with birds, even making another horror movie called "The Birds" (1963).
Christopher Lee was asked which part of Psycho did he consider the scariest, and he replied, 'Well, it wasn't the shower scene because you knew something was going to happen, right? So it wasn't that. What was scary was when the detective, played by Martin Balsam, climbed the stairs in the house to the second floor when a door opens and out steps a woman who stabs him, causing him to fall backward to his death. Now that scene I found very scary.'