In his essay on the uncanny, Das Unheimliche, Freud said that the uncanny is the only feeling which is more powerfully experienced in art than in life. If the horror genre required any justification, I should think this alone would serve as its credentials.
Stanley KubrickThe reality of the final moment, just before shooting [the scene], is so powerful that all previous analysis must yield before the impressions you receive under these circumstances, and unless you use this feedback to your positive advantage, unless you adjust to it, adapt to it and accept the sometimes terrifying weaknesses it can expose, you can never realize the most out of your film.
Stanley Kubrick