What happens in our brains while we watch a movie by Alfred Hitchcock, master of suspense? During moments of high excitement, the calcarine sulcus — a brain area that receives and processes visual information — narrows our field of vision and, when calm is returned, broadens our field of view, a study from Georgia Institute of Technology finds.
“The scope of attention changes dynamically in response to emotional content,” wrote the researchers in their published work.
A "sulcus" is simply a groove. In neuroanatomy, this word refers to any of the shallow furrows on the surface of our brains. The calcarine sulcus, in particular, is located on the occipital lobe, where our brains interpret visual information. The back of the calcarine sulcus is where our central visual field is located, while the peripheral visual field is in the front.
For the current study, Dr. Matt Bezdek, a Georgia Tech psychology researcher, asked a simple question: Since the calcarine sulcus is instrumental to how we process visual information, does the pattern of its activity shift during moments of suspense to change the way we see?
Bezdek and his co-researchers enlisted the help of 18 participants who (happily) volunteered to watch scenes from 10 thrillers while lying in an MRI machine. As clips from each of the movies played at the center of the screen, a flashing checker board pattern appeared around the edges. This unusual frame was used because neurons in the calcarine sulcus are typically attracted to such movement. So, by presenting the flashing pattern at all times, the researchers would be able to see whether suspense directly affected the usual response of neurons.
What did the science team discover? An ebb and flow of brain activity occurred in each participant’s calcarine sulcus in response to the movie clips. Growing suspense produced a decrease in activity at the front of the calcarine sulcus (peripheral visual processing) and an increase in activity at the back (central visual processing). This suggests, the researchers say, during moments of increased narrative suspense, the brain boosts our focus on important, central information, while suppressing attention paid to peripheral stuff.
During the famous scene in “North by Northwest,” then, where Cary Grant is nearly killed by a low-flying airplane, the brain narrowed its visual focus — participants literally developedtunnel vision — in order to increase processing of critical information and ignore any visual content that didn’t matter. Once the excitement faded, the same process was reversed. Participants’ brains shifted activity along the calcarine sulcus, broadening their attention to include the periphery.
“During the most suspenseful moments, participants focused on the movie and subconsciously ignored the checker boards,” Dr. Eric Schumacher, an associate professor, stated in a press release. “The brain narrowed the participants' attention, steering them to the center of the screen and into the story.”Clearly, Hitchcock's movies mess with your head in more ways than one.
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