If scary movies make you jump a lot of that likely has to do with the music. University of Wollongong researcher Rebecca Mursic took at look at a specific set of tones that are known for raising hairs called The Shepard scale. When played continuously, with notes either ascending or descending in pitch, the progressions make the sounds seem as if they are rising or dropping endlessly. It's an auditory illusion, but many directors use The Shepard scale to build suspense in their films. When Mursic played the scale to participants they reported a range of reactions-- from feelings of motion sickness to a mix of emotional disturbances. Most people became nervous and agitated. The Shephard scale is used often in the soundtracks of Christopher Nolan directed films-- it can be heard in The Dark Knight and Dunkirk.