The most effective horror movies play on viewers' senses. From Alfred Hitchcock to M. Night Shyamalan, horror-film makers have always loved messing with our visual and auditory perception, using camera trickery, calculated shot composition, and immersive sound design to instill fear in their audiences. In this short documentary, Insider provides a breakdown of some of their go-to techniques and explains what makes these classic horror devices so effective at crafting fear.—Anonymous