How are Doppelgängers used in Vertigo?

Doppelgängers are common in film and literature, often figured as a twin, a mirror-image or a copy of the protagonist. They also represent a signifcant motif in the psychoanalytical study of film, especially Vertigo.

As a symbol of psychomachia - a conflict within the soul - the doppelgänger represents the struggle between vice and virtue within an individual, allowing filmmakers like Alfred Hitchcock to visualise the different aspects of the human personality in a characters like Scottie and Madeleine/Judy. Madeleine allows Scottie to be virtuous, to save and nurture from her fall in San Francisco Bay, whereas Judy allows Scottie to manipulate and change her appearance to more resemble Madeleine, acting as a vessel for his trauma and recovery. He sees Judy as a cure for his 'castration anxiety' and feminisation as a result of his fall in the film's opening, satisfying his masculine desires to control, possess and be active over a female character - but he ultimately fails when Madeleine later falls to her death. There are multiple cases in Vertigo when one character could be considered the doppelgänger or double of another, such as Gavin and Scottie, whom Scottie wishes he could be if he were not feminised and passive - dominating, wealthy, masculine and in-control.

Sigmund Freud described the arrival of a doppelganger or double as representing "the return of the repressed" and this is demonstrated in Vertigo's second act.