Sigmund Freud's theory breaks up into different parts which leads to different meanings. However the film How To Be Single really addresses their characters to the id, ego and super-ego part. First off we are introduced to the main characters, Robin (played by Rebel Wilson) who would be the Id, Alice (played by Dakota Johnson) who is the ego and Alice's sister, Meg (played by Leslie Mann) who would be the super-ego. Starting off with the id, the character who urges to do anything just for the pleasure and doesn't consider realistic. For example, Robin is the really outgoing type, she goes out to party every night and does not have anything she would not do, she never is serious and doesn't think of anything but to have fun (which would fulfil her pleasure). The next character would be the super-ego, Meg. She works in a hospital (which would be considered a really good, responsible job) and a single woman trying to get pregnant (which also could be considered responsible). However, throughout the film she becomes really naive - as hanging around with Robin (the party animal) she begins to become more of a fun character and she has the choice to decide whether she wants to be sensible or have fun. However the main character Alice, the ego, has been between both the super-ego and the id but always makes the right, sensible decisions. Which relates back to Freud's theory, the id is when the 'child' is unconscious and only wants to do things for their pleasure, not really worrying about what the consequences are. The ego is the sensible part of the 'brain' - it develops ideas and problems from the outside world and learns that not always the urges can not be fulfilled. The super-ego develops on the lessons that the id and the ego have learnt, usually mediates between the two, Freud believed that a mentally healthy person had a strong ego to keep the id and super-ego balanced.
