Castration anxiety
Castration anxiety is a fear posited by Sigmund Freud in his writings on the Oedipus complex at the genital stage of sexual development. It asserts that boys seeing a girl's genitalia will falsely assume that the girl must have had her penis removed, probably as punishment for some misbehavior, and will be anxious lest the same happen to him.
It is worth noting that in some cultures, notably 19th century Europe, it was not unheard of for parents to threaten their children with castration, or to otherwise threaten their genitals, a phenomenon Freud documents several times. This may help to explain Freud's reasoning regarding castration anxiety's role in human development.
Little Hans
Little Hans was a young boy who was the subject of an early but extensive study of castration anxiety and the Oedipal complex by Sigmund Freud. His neurosis took the shape of a crippling phobia of horses (Hippophobia). Freud wrote a summary of his treatment of Little Hans, in 1909, in a paper entitled "Analysis of a Phobia in a Five-year-old Boy". This was one of just a few case studies which Freud published. Hans became fearful of going out into the street, with his fear focused on horses and heavily loaded vehicles, which he was afraid would fall over. Freud saw Hans only once in his office during the consultation, and carried out most of the work by gathering information from Hans' father (one of his colleagues) and providing ideas to the father for what to say and do to improve the situation, which was referred to in the case study as "nonsense". The information gathered from the father included reports of Hans' dreams, his behaviors, and his answers to questions. Freud had recently written a book about the development of sexuality, and he believed that what he learned from Hans' situation backed up his theory. Hans' fear and anxiety were thought to be the result of several factors, including the birth of a little sister, his desire to replace his father as his mothers' mate, conflicts over masturbation, and others. The anxiety was seen as stemming from the incomplete repression and other defense mechanisms being used to combat the impulses involved in his sexual development. Hans' behavior and emotional state did improve when he was provided with information by his father, and the two became closer. Competing theories of phobias might focus more on conditioning of fear through environmental means and the signaling function of anxiety. In 1922, Sigmund Freud wrote a short Postscript to the case study, in which he reported that Little Hans had appeared in his office as a "strapping youth of nineteen", who "was perfectly well, and suffered from no troubles or inhibitions".