And why some scenes feel so real.

By Real Simple
Updated July 28, 2015
Couple watching scary movie
Credit: Brand New Images/Getty Images

Do you ever find yourself repeating a silent mantra ("It's only a movie") during a thriller? It might seem silly that you need to remind yourself of that fact, but new evidence supports the idea that we are somewhat "transported" into scarier movies—particularly the more suspenseful scenes.

Researchers at the Georgia Institute of Technology looked to understand how people get "lost in the story" when watching scary movies. They asked participants to watch scenes from 10 scary movies, including a few from the ultimate scary movie director, Alfred Hitchcock. While each scene played, the researchers had a checkerboard pattern appear around the edge of the screen, and monitored brain activity—specifically, the area of the brain that processes visual information. They found that as suspense increased, the brain "narrowed" participants' vision. As suspense ebbed, the visual attention became broader, allowing them to process the scene, as well as the checkerboard border. The findings are set to be published in the journal Neuroscience.

"It's a neural signature of tunnel vision," lead author Eric Schumacher said in a statement. "During the most suspenseful moments, participants focused on the movie and subconsciously ignored the checker boards. The brain narrowed the participants' attention, steering them to the center of the screen and into the story."

In the mood for a scary movie tonight? See our ultimate list of the spookiest flicks—they're not just for Halloween.