A new study finds that skilled readers do not rely on sounds when reading but rather retrieve words purely from a “visual dictionary.” The research, conducted by neuroscientists at Georgetown University Medical Center, may provide insight into the brain-based causes of dyslexia.
The concept of a visual dictionary is not a new one to reading teachers, who often call words that do not need to be sounded out “sight words.” Emerging readers frequently memorize some sight words before they’ve even mastered letter-sound correspondence.
But as the study’s lead researcher, Laurie Glezer, Ph.D., explains, there’s been disagreement about how known words are accessed in the brain. “One camp of neuroscientists believes that we access both the phonology and the visual perception of a word as we read them and that the area or areas of the brain that do one, also do the other,” she states in a press release, “but our study proves this isn’t the case.”
The researchers used functional magnetic resonance imaging to look at 12 volunteers’ neural activity during a word-recognition activity. They saw that homonyms with different spellings, like “hare” and “hair,” activated different neurons.
“If the sounds of the word had influence in this part of the brain we would expect to see that they activate the same or similar neurons, but this was not the case, ‘hair’ and ‘hare’ looked just as different as ‘hair’ and ‘soup’. This suggests that all we use is the visual information of a word and not the sounds,” says Glezer.
That’s not to say students shouldn’t learn phonics—Glezer explains that independent readers need to sound out a word the first few times before it is added to the visual dictionary.
The finding could help people with reading disorders, she says. “For example, if people with dyslexia have a problem forming this visual dictionary, it may be that there could be ways of helping train children with dyslexia to form a more finely tuned visual dictionary.”
