One of the top mistakes I see modern horror movies making repeatedly is the overuse of jump scares. They often get a bad rap because of this, however, jump scares are a great tool in moderation.
People underestimate the complexity of a scare. Inspiring terror is an art form and an exercise in patience. Too many people rely on loud noises and visuals alone when this is only part of the equation.
The greatest threat to souring a scare is a lack of tension. Tension is the key ingredient to a jump scare. There are two places where a jump scare is most effective in a movie, at the peak of tension and close to the resolution of it.
Imagine the audience as a piece of thread. Filmmakers slowly begin to pull on the thread. As the thread becomes taught, dread and anticipation are being built. The longer the thread is held at max tension the more effective the scare can be. The scare itself is the thread breaking. Horror is essentially this process being repeated over and over again.
My favorite example of this is the defibrillation scene in John Carpenter’s The Thing. While the survivors of this arctic outpost squabble amongst themselves, afraid one of their number is an extraterrestrial in disguise, a survivor is fatally injured. Still, at each other’s throats, the doctor attempts to resuscitate their fallen comrade only to find the dead man isn’t really dead.
The second most effective place to put a jump scare is at the resolution of the climax. We all know this moment. Its when our protagonists have seemingly defeated the great evil, but the antagonist rears its ugly head for one last scare.
Its that moment Jason jumps out of the lake at the end of Friday the 13th and when Freddy pulls Nancy’s mom through the glass of her front door. When the audience sees the finish line in sight, that’s when they are most vulnerable.