A Psychoanalytic reading of Alien (1979).
In 1896 Sigmund Freud coined the phrase "psychoanalysis", which basically is a theory that there are three forces that control the body, they are the id, the ego and the superego.
The id is the unconscious, it contains what is inherited from previous generations and more importantly, the instincts or desires of the person. The unconscious is made up of fantasies, wishes, desires repressed or not.
The ego is conscious, and exists between the id and the exterior world. The ego strives to achieve enjoyment and tries to avoid discomfort or displeasure.
The superego however is the inner parent, who is managed by the id. The superego is responsible for the influence of other authority figures such as parents or role models.
In An Outline of Psychoanalysis (Freud 1949) Freud states that the ultimate cause of all behaviour stems from the instincts Eros (love) and the death / destruction instinct.
But how does this apply to Alien (dir: Ridley Scot, 1979).
The Alien obviously represents the id, the alien operates on pure instinct as it has not been taught otherwise by other stimuli, he succumbs to whatever desire he is feeling at the time. For instance when he kills / "rapes" Lambert.
The superego is represented by "Mother" the computer that cares for the crew by guiding and instructing them, much like a mother.
The ego is could be argues to be Ripley, as she takes orders from Mother, and tries to suppress the id or alien.
Another major part of psychoanalysis is the Oedipus complex. This theory states that a child goes through 3 stages of development. The oral stage where the (predominantly) male child gains pleasure and gratification from breast feeding, the anal stage where the child is fascinated or disgusted by its natural bodily functions. Finally the child goes through a phallic stage where the child seeks pleasure from self stimulation, from this castration theory can result if the child is told not to pleasure himself I.