The screenplay is relatively faithful to the novel, with a few notable adaptations by Hitchcock and Stefano. Stefano found the character of Norman Bates—who, in the book, is middle-aged, overweight, and more overtly unstable—unsympathetic, but became more intrigued when Hitchcock suggested casting Anthony Perkins. Stefano eliminated Bates' drinking, which evidently necessitated removing Bates' "becoming" the mother personality when in a drunken stupor. Also gone is Bates' interest in spiritualism, the occult and pornography. Hitchcock and Stefano elected to open the film with scenes in Marion's life and not introduce Bates at all until 20 minutes into the film rather than open with Bates reading a history book as Bloch does. Writer Joseph W. Smith notes that "Her story occupies only two of the novel's 17 chapters. Hitchcock and Stefano expanded this to nearly half the narrative". He likewise notes there is no hotel tryst between Marion and Sam in the novel. For Stefano, the conversation between Marion and Norman in the hotel parlor in which she displays a maternal sympathy towards him makes it possible for the audience to switch their sympathies towards Norman Bates after Marion's murder. When Lila Crane is looking through Norman's room in the film, she opens a book with a blank cover whose contents are unseen; in the novel, these are "pathologically pornographic" illustrations. Stefano wanted to give the audience "indications that something was quite wrong, but it could not be spelled out or overdone." In his book of interviews with Hitchcock, François Truffaut notes that the novel "cheats" by having extended conversations between Norman and "Mother" and stating what Mother is "doing" at various given moments.