Tech & Science
When literate adults pick up a book, they don’t start sounding out each word letter by letter or sound by sound, the way their kindergarten or first-grade teacher probably told them to do when they were first beginning to read. Instead, as a new study shows, their brains recognize whole words they’ve seen before, which facilitates quicker reading.
Researchers at Georgetown University Medical Center’s Department of Neuroscience published their findings Tuesday in The Journal of Neuroscience. The paper, “Adding Words to the Brain’s Visual Dictionary: Novel Word Selectively Sharpens Orthographic Representations in the VWFA,” demonstrates the brain’s ability to adapt and learn to recognize new words. The brain can add new words to its “visual dictionary” even if they are made up and have no meaning attached to them, the researchers found.
In their previous work, the researchers had shown that the area in the left side of the visual cortex—roughly behind the left ear—seemed to have a visual dictionary that recognized whole words as images. The visual word form area (VWFA), as it’s called, is opposite a similar brain area on the right side, called the fusiform face area (FFA), that quickly recognizes faces.
“One area is selective for a whole face, allowing us to quickly recognize people, and the other is selective for a whole word, which helps us read quickly,” Maximilian Riesenhuber, the paper’s senior author, says in a press release.
In the current study, Riesenhuber and his colleagues delved deeper, asking whether this recognition of a familiar word in the visual dictionary was associated with meaning and whether new words could be added.
The team began with 25 adult participants, but only a dozen were included in the study’s analysis. (Of the rest, some dropped out, in some the VWFA could not be identified, and others were excluded for other reasons.) Each participant had a brain scan using a kind of fMRI (or functional magnetic resonance imaging) technology called rapid adaptation, during which they were shown pairs of real words. In each pair, the two words were either exactly the same, different by only one letter or completely different. It turned out that the response level in the VWFA was the same whether the words were only one letter different or completely different, indicating that the neurons in the brain recognize the entire word at once rather than looking at its components.
Next, the researchers wanted to test if the brain would react to pseudo-words, or nonsense words, in the same way. During the first scan, the neurons showed no signs of recognizing these nonsense words. But then the researchers had the participants undergo training sessions to learn to recognize 150 pseudowords. They had to be able to remember and indicate that they’d seen these “words” before. When participants could pick out the fake words they’d learned from other nonsense words with a certain level of proficiency, the researchers did another scan. The second time around, response levels to the now-familiar pseudowords were the same as those for real familiar words.
Lead author Laurie Glezer says that once you’re a skilled reader, you don’t need to process the sounds of each letter in a word anymore, and that is “what allows for fast, efficient reading that literate people are able to do.”
Literate people can also learn visual representations of words without any semantic information. In other words, they respond to what the word itself looks like, even if they don’t know what it means. Their brains could learn to recognize the pseudo-word soat just as they would the real word boat, if such people were trained to do so the way the participants in the study were.
The findings and future research could have implications for how we teach reading, particularly to those who struggle with traditional methods. “For people who cannot learn words by phonetically spelling them out—which is the usual method for teaching reading—learning the whole word as a visual object may be a good strategy,” Riesenhuber said in the press release.
While it’s difficult to extrapolate directly from this study to development and teaching methods because the participants were all proficient adult readers, Glezer says, “this is the first step in trying to understand what it is that goes wrong, what gets in the way of people being able to learn to read.”
The researchers are already pursuing additional avenues to investigate these questions. Working with Guinevere Eden, a professor in the Department of Pediatrics and director of the Center for the Study of Learning at Georgetown, Glezer’s team is looking at the VWFAs of the brains of people who have dyslexia to see if the visual tuning in their brains is the same or different. Riesenhuber says they also have an ongoing study looking at how words, once recognized, then get connected to meaning.