Books are just as powerful as movies when it comes to their potential to prod our brains into such reactions as delight, pain and disgust, new research suggests.
In fact, reading any printed or electronic words, for instance, about someone unknowingly drinking a glass of sour milk is just as likely to make you gag as watching that scene in "There's Something About Mary," when the title character puts the, er, bodily fluid that she thinks is hair gel into her hair, the study finds.
Researchers have known that watching someone perform an action, for example, kicking a ball, activates the parts of the viewer's brain, via so-called mirror neurons, that govern that motion.
Similarly, when we view a scene in which another person exhibits delight, pain or disgust, the parts of our brain that react when we experience those emotions ourselves are activated. Who hasn't seen another person retch and reacted by heaving themselves, or at least thought about it?
Scientists at the NeuroImaging Center of the University Medical Center in Groningen, Netherlands, wanted to see if that same brain region that governs those three emotions or reactions — the anterior insula — was activated when people read about someone experiencing disgust.
To test this, they placed participants in an fMRI scanner, which measures changes in blood flow in the brain, and showed them 3-second movie clips of an actor sipping from a cup and then looking disgusted.
"Later on, we asked them to read and imagine short emotional scenarios," said study team member Christian Keysers. "For instance, walking along a street, bumping into a reeking, drunken man, who then starts to retch, and realizing that some of his vomit had ended up in your own mouth."
Finally, the researchers had the participants taste an unpleasant solution while in the scanner.
"Our striking result is that in all three cases, the same location of the anterior insula lit up," Keysers said. Whether this same correspondence in the brain is true of other emotions, scientists aren't sure yet, Keysers told LiveScience.
The results of the study are detailed in the online journal PLoS ONE.
Scientists know that the anterior insula is the seat of the feeling of disgust, because people with brain damage to that area lose the capacity to feel disgusted.
"If you give them sour milk, they would drink it happily and say it tastes like soda," Keysers said.
But for people with normally-functioning anterior insulas, sipping that sour milk will result in them spitting it right back out with a "blech." Having the same reaction when watching someone else spit out the milk is an evolutionary advantage: You won't try the same milk if you register the other person's disgust.
"What this means is that whether we see a movie or read a story, the same thing happens: We activate our bodily representations of what it feels like to be disgusted," Keysers said. "And that is why reading a book and viewing a movie can both make us feel as if we literally feel what the protagonist is going through."