Reading may be fundamental, but how the brain gives meaning to letters on a page has been a mystery. Two new studies fill in some details on how the brains of efficient readers handle words. One of the studies, published in the April 30 Neuron, suggests that a visual-processing area of the brain recognizes common words as whole units. Another study, published online April 27 in PLOSONE, makes it known that the brain operates two fast parallel systems for reading, linking visual recognition of words to speech.
Maximilian Riesenhuber, a neuroscientist at Georgetown University in Washington, D. C. , wanted to know whether the brain reads words letter by letter or recognizes words as whole objects. He and his colleagues showed sets of real words or nonsense(无意义的词语)words to volunteers undergoing FMRI scans. The words differed in only one letter, such as “farm” and “form” or “soat” and “poat”, or were completely different, such as “farm” and “coat”or “poat” and “hime”.The researchers were particularly interested in what happens in the visual word form area, or VWFA, an area on the left side of the brain just behind the ear that is involved in recognizing words.
Riesenhuber and his colleagues found that neurons(神经元)in the VWFA respond strongly to changes in real words. Changing “farm” to “form”, for example, produced as great a change in activity as changing “farm” to“coat”, the team reports in Neuron. The area responded slowly to single-letter changes in made-up words.
The data suggests that readers grasp real words as whole objects, rather than focusing on letters or letter combinations. And as a reader's exposure to a word increases, the brain comes to recognize the shape of the word. “Meaning is passed on after recognition in the brain”, Riesenhuber says.
The researchers don't yet know how longer and less familiar words are recognized, or if the brain can be trained to recognize nonsense words as a unit.
