the audience with a greater sense of danger. It's easier for them to identify with him than with a guilty man on the run." One of his constant themes were the struggle of a personality torn between "order and chaos"; known as the notion of "double", which is a comparison or contrast between two characters or objects: the double representing a dark or evil side. According to Robin Wood, Hitchcock had mixed feelings towards homosexuality despite working with gay actors in his career. Donald Spoto suggests that Hitchcock's sexually repressive childhood may have contributed to his exploration of deviancy. During the 1950s, the Motion Picture Production Code prohibited direct references to homosexuality but the director was known for his subtle references, and pushing the boundaries of the censors. Moreover, Shadow of a Doubt has a double incest theme through the storyline, expressed implicitly through images. Author Jane Sloan argues that Hitchcock was drawn to both conventional and unconventional sexual expression in his work, and the theme of marriage was usually presented in a "bleak and skeptical" manner. It was also not until after his mother's death in 1942, that Hitchcock portrayed motherly figures as "notorious monster-mothers". The espionage backdrop, and murders committed by characters with psychopathic tendencies were common themes too. In Hitchcock's depiction of villains and murderers, they were usually charming and friendly, forcing viewers to identify with them. The director's strict childhood and Jesuit education may have led to his distrust of authoritarian figures such as policemen and politicians; a theme which he has explored. Also, he used the "MacGuffin"—the use of an object, person or event to keep the plot moving along even if it was non-essential to the story. Some examples include the microfilm in North by Northwest and the stolen $40,000 in Psycho. Hitchcock appears briefly in most of his own films. For example, he is seen struggling to get a double bass onto a train (Strangers on a Train), walking dogs out of a pet shop (The Birds), fixing a neighbour's clock (Rear Window), as a shadow (Family Plot), sitting at a table in a photograph (Dial M for Murder), and riding a bus (North by Northwest, To Catch a Thief). Representation of women Hitchcock's portrayal of women has been the subject of much scholarly debate. Bidisha wrote in The Guardian in 2010: "There's the vamp, the tramp, the snitch, the witch, the slink,