Evaluation of the Double-Deficit Hypothesis in college students referred for learning difficulties

The present study explored the double-deficit hypothesis (DDH) in a sample of 146 college students with and without reading disabili-ties (RD). The results indicated that although both phonological awareness (PA) and visual naming speed (VNS) contributed to perfor-mance on measures of decoding and comprehension, their relative contribution was influenced both by the nature of the stimulus (word vs. nonword vs. text) and by the conditions of the task (timed vs. untimed). Similar results were obtained using an individual differences approach, or when between-group comparisons were made of individuals with deficits in PA or VNS. The relative representation of DDH subgroups in groups of adults with RD varied based on the classification criteria used to define RD. These results support the DDH, ex-tend its applicability to adults, and have implications for diagnostic decision making. Word reading ability is stronglyrelated to phonological pro-cessing skills (phonological awareness; PA), frequently measured via phoneme deletion and blendin