About 5 to 10 percent of American children are diagnosed as dyslexic. Historically, the label has been assigned to kids who are bright, even verbally articulate, but who struggle with reading — in short, whose high IQs mismatch their low reading scores. On the other hand, reading troubles in children with low IQs have traditionally been considered a byproduct of their general cognitive limitations, not a reading disorder in particular. Now, a new brain-imaging study challenges this understanding of dyslexia. "We found that children who are poor readers have the same brain difficulty in processing the sounds of language whether they have a high or low IQ," says John D. E. Gabrieli of MIT. "Reading difficulty is independent of other cognitive abilities."