A Synthesis of Research on Reading from the National Institute of Child Health and Human Development

Other Important Research Questions and Findings

The scope of the NICHD research program is much broader than identifying effective methods for treating reading difficulties. Some of these research questions and the findings are briefly described below.

Research Question: Are there medical reasons to explain why 20 to 40% of the population do not naturally develop phonemic awareness?
Finding: Yes, sophisticated modern brain research using neuroimaging and other technologies show a unique brain signature for many, but not all, children without phonemic awareness. This neuroimaging research is being conducted at several NICHD sites, thus providing the opportunity for replication.

Research Question: Are reading disabilities inherited?
Finding: Twin studies have found strong evidence for genetic etiology of reading disability, with deficits in phonemic awareness reflecting the greatest degree of heritability. There is also behavioral genetic evidence for degrees of heritability for letter processing.

Research Question: How does ADD relate to learning disabilities?
Finding: Disorders of attention and reading disabilities often coexist, but the two disorders appear distinct and separable with respect to the effects of attention-deficit disorder (ADD) on cognitive tasks. For example, it has been found that ADD children perform poorly on rote verbal learning and memory tasks, but relatively well on naming and phonemic awareness tasks. The converse appears to be the case for children with reading disabilities.

Research Question: Are more boys than girls reading disabled?
Finding: Despite the widely held belief that boys are more likely to have reading disabilities than girls, research has shown that as many girls as boys have difficulties learning to read. More boys are identified by teachers in school because of their tendency to be more rowdy and active than girls.