Research Project V addresses the definition, classification and etiology of individual differences in comprehension and learning disabilities in comprehension deficits. We use extensive assessments of both oral and reading comprehension and passage fluency, across simple and complex discourse, to understand the genetic, cognitive, and developmental aspects of comprehension. Twins and siblings selected for deficits either in reading, comprehension, writing, and/or ADHD, as well as normal-range control twins are tested. Our goal is to advancing understanding of the functional architecture of comprehension and diagnosis of deficits.
Our approach involves 3 prongs.
One is to use multivariate analyses of component skills and knowledge to analyze individual differences and deficits in both reading comprehension and listening comprehension, across different age groups and across different comprehension tests. This advances not only understanding of comprehension skills but also diagnoses of comprehension deficits (CD). By comparing cognitive profiles on component skills of children diagnosed as CD across different methods, we can learn the basis for the current unfortunate situation of dramatic inconsistencies across tests in who gets identified as having CD.
A second prong is to use behavioral genetic analyses to assess the etiology of individual differences and deficits in comprehension in terms of genetic and environmental influences. These analyses also assess the degree to which component skills share genetic influences and thus the degree to which they represent different possible paths to developing comprehension difficulties.
The third prong is to further define the phenotype by finding variables often ignored by current tests that could be influencing comprehension performance, such as the centrality of ideas and how prior knowledge of passage topic influences comprehension and fluency.
In collaboration with other CLDRC projects, we will also be assessing whether similarities in skills and similar genes between discourse comprehension and writing (Project II), assessing molecular genetic linkage and association for deficits in comprehension (Project IV), and longitudinally assessing stability of comprehension problems (Project VI).
