During the filming, Alfred Hitchcock placed the prop used as Mrs. Bates’ corpse in Janet Leigh’s dressing room without her knowledge. He did this to test the fear factor of the prop.
Psycho (1960)
In order to implicate viewers as fellow voyeurs Alfred Hitchcock used a 50 mm lens on his 35 mm camera. This gives the closest approximation to the human vision. In the scenes where Norman is spying on Marion this effect is felt.
The entire picture was shot on one set, which required months of planning and construction. The apartment-courtyard set measured 98 feet wide, 185 feet long and 40 feet high, and consisted of 31 apartments, eight of which were completely furnished.