Book explains why Halloween attractions make us "Scream"

The book documents Kerr's adventures around the world experiencing extreme attractions, ranging from the tallest roller coasters in Japan to the CN Tower's EdgeWalk in Toronto, where participants are tethered to the skyscraper for an outdoor walk 116 stories off the ground.

Kerr also works at a haunted attraction in Pittsburgh called ScareHouse, analyzing customer responses to help keep the fright levels just right.

[...] there's another side to fear that's fun and fulfilling, and that's the sweet spot sought by recreational activities — whether skydiving, ziplining, roller coasters or haunted houses.

[...] we know from science that seeing the whites of people's eyes will activate the amygdala — the emotional processing center of our brain."

Startling sounds, fast-moving props and other sudden visual effects also trigger instinctive responses, upping the fear factor without putting people in real danger.