Some people describe reading as being similar to watching a movie in their head. Scientists long have wondered how the brain creates such vivid experiences out of simply viewing strings of letters. Typically, studies have focused on one small aspect of language. Word length, perhaps, or how complex a sentence is. A study has now evaluated all levels of reading, from word length and order, to plot, character and emotion. And it did so all at once. Its new results reveal some of the ways that our brains turn words into vivid stories.
Computer scientists Leila Wehbe and Tom Mitchell led the new study. Both work at Carnegie Mellon University in Pittsburgh, Pa. Their team started with information from earlier studies. Then they used those data to develop a computer model of which brain regions turn on as we read.
To test the model, the team recruited people who had read the Harry Potter books or watched the movies. “We chose Harry Potter because many people have read the books and are familiar with the characters and the Harry Potter world,” Wehbe explains. That choice was important. The researchers wanted people to be able to picture a particular scene unfolding as they read about it.
The researchers chose chapter 9 from Harry Potter and the Sorcerer’s Stone. (The chapter describes Harry’s first flying lesson.) The scientists then identified each word of the selected chapter as having at least one of 195 different features. These included character names, emotions and movements. They also included pronouns, verbs and other features of grammar.
Next, the researchers tested their model. To do this, they scanned the brains of people as they read the chapter. Their tool was a magnetic resonance imaging — or MRI — machine. It uses a strong magnetic field to monitor blood flow in the brain. Brain areas consume more oxygen as they become active. So blood flows increase in those areas as they supply the needed oxygen. Wehbe and her team tracked changes in that blood flow as people read. Conducting MRI scans while some event occurs, as here, is known as functional MRI (or fMRI).
People inside the MRI chamber must remain perfectly still. But Wehbe also needed them to be able to read. So she displayed the Harry Potter chapter on a computer screen inside the MRI chamber, one word at a time.
Each word flashed on for half a second. The machine produced a new scan of the working brain each two seconds. So each scan would have captured impacts of reading four words. Areas that were active as they read each group of words showed up on a digital map of the brain.
After tweaking their computer model, the researchers found it to be remarkably accurate. They could predict which of two passages people were reading simply by analyzing their brain activity. And those predictions were right three times in every four. The researchers published details of their findings November 26 in the journal PLOS ONE.
Wehbe notes that the model could be used to study how the brain changes as we learn to read. Perhaps we use regions of the brain differently as we become more experienced, she says.
“I am excited by this paper,” says Evelina Fedorenko. “I think it opens up new avenues for language research.” Fedorenko, who was not involved in the Harry Potter tests, studies the development of language. She works at Massachusetts Institute of Technology and Massachusetts General Hospital in Boston.
Why do we experience a book as if it were a movie playing in our heads? It might be because the brain regions that process everyday tasks also turn on when we read, Wehbe says.
For example, in everyday life, we use a particular region to imagine what other people are thinking. That same region seems to become active when we identify characters in a story, she notes. Another area of the brain becomes active when we watch people move. The area lights up too when we read about a character in motion — like someone flying by broom. Thanks to the way our brains process information, even a simple tale can become an extraordinary experience.
brain scan The use of an imaging technology to view structures inside the brain, typically by using X rays or a magnetic resonance imaging (or MRI) machine. With MRI technology — especially the type known as functional MRI (or fMRI) — the activity of different brain regions can be viewed as some event takes place, such as viewing pictures, computing sums or listening to music.
computer model A program that runs on a computer that creates a model, or simulation, of a real-world feature, phenomenon or event.
computer science The scientific study of the principles and use of computers.
concentration A measurement of how much of one substance has been dissolved into another.
digital (in computer science and engineering) An adjective indicating that something has been developed numerically on a computer or on some other electronic device, based on a binary system (where all numbers are displayed using a series of only zeros and ones).
fMRI (functional magnetic resonance imaging) A special type of machine used to study brain activity. It uses a strong magnetic field to monitor blood flow in the brain. Tracking the movement of blood can tell researchers which brain regions are active. (See also, MRI or magnetic resonance imaging)
information (as opposed to data) Facts provided or trends learned about something or someone, often as a result of studying data.
magnetic resonance imaging (MRI) An imaging technique to visualize soft, internal organs, like the brain, muscles, heart and cancerous tumors. MRI uses strong magnetic fields to record the activity of individual atoms.