A bush on the edge of the clearing quivered. … Then, out of the shadows, a hooded figure came crawling across the ground like some stalking beast. Harry, Malfoy, and Fang stood transfixed. The cloaked figure reached the unicorn, lowered its head over the wound in the animal’s side, and began to drink its blood.

And here’s another passage from the final book of the series:

He got up off the floor, stretched and moved across to his desk. Hedwig made no movement as he began to flick through the newspapers, throwing them on to the rubbish pile one by one; the owl was asleep, or else faking; she was angry with Harry about the limited amount of time she was allowed out of her cage at the moment.

Which passage did you find more engaging? Chances are it was the first. While the second passage might advance the plot, the first passage has drama, tension, and irresistible vampire-like behavior stuffed into a matter of four lines. It’s the type of action that helps readers get lost in a book. And it’s precisely this ability to immerse readers that helps sell hundreds of millions of copies.

Call it magic.

The results of our experiment, that action is more engrossing than scene-setting, may be unsurprising. But a group of psychologists led by Chun-Ting Hsu of the Free University of Berlin believe this approach, when used in conjunction with neural imaging, can help scientists understand exactly what’s going on in our brains when we get pulled in by a great story. They describe just such a study–calling it the “first attempt to understand the neural mechanisms of immersive reading experience”–in an upcoming issue of the journal NeuroReport.

Scholastic/Mary GrandPre’

Hsu and collaborators recruited test participants to enter a brain scanner and read passages of Harry Potter (translated into German) about four lines long. Some of the passages were fear-inducing, like those at the top of this post, while some were neutral, like those in the second block above. (While the paper doesn’t list any actual examples used in the study, the above passages seem like fair representations.) A separate group of participants rated each passage for how immersive they found it to be.

As expected, the fearful passages received significantly higher ratings for immersion than the neutral ones–more likely to get readers lost in the book. In the middle cingulate gyrus area of the brain, Hsu and company detected a much stronger link between immersion ratings and neural activity for the fearful passages than for the neutral ones. The middle cingulate gyrus is considered part of the brain’s empathy network, and has been associated with pain empathy in particular.