Horror cinema exploits a fundamental distinction between visibility and conscious awareness: an object can be plainly present yet escape notice when attention is directed elsewhere. In Hereditary, viewers concentrating on Peter may initially overlook Annie crouching on the ceiling. This is inattentional blindness, famously demonstrated in an experiment in which about half the participants counting basketball passes missed a person walking through the game in a gorilla costume. Change blindness, a related failure to detect alterations, underpins a scene in The Conjuring 2: while attention rests on Ed Warren, Janet transforms into an old man in the slightly blurred background.
Editing can also harness gaze cueing, our tendency to follow another person’s direction of attention. By showing a frightened character looking upwards before revealing a threat, a director steers the audience towards a scare. Conversely, the wide opening shot of It Follows offers no clear gaze or cut to guide viewers. They must search the frame for possible danger, with uncertainty itself generating tension.
Other techniques exploit the division between detection and identification. Central vision supplies fine detail and colour, whereas peripheral vision is particularly sensitive to movement and low light. Movement at the edge of sight prompts a rapid eye movement towards it; the interval before recognition can produce unease. Horror also draws on pareidolia, the tendency to perceive faces in patterns where none exist. The Night House arranges objects so that figures and faces appear to emerge, while The Haunting, released in 1963, uses a wall pattern to similar effect.
