Nonword reading and Stroop interference: what differentiates attention-deficit/hyperactivity disorder and reading disability?

Background: Attention deficits and impaired reading performance co-occur more often than expected by chance; however, the underlying mechanism of this association still remains rather unexplored.

Method: In two consecutive studies, children aged 8 to 12 years with attention-deficit/hyperactivity disorder (ADHD) and children with reading disability (RD) were examined using a 2 (ADHD versus no ADHD) × 2 (RD versus no RD) factorial design. To further delineate deficient interference control from reading processes, we used a newly developed self-paced word/nonword reading task (Experiment 1, n = 68) and a modified computerized Stroop paradigm, including an orthographic phonological neighbor (OPN) condition (Experiment 2, n = 84).