Development and functional significance of private speech among attention-deficit hyperactivity disordered and normal boys.

We compared the development of spontaneous private speech and its relationship to self-controlled behavior in a sample of 6- to 12-year-olds with attention-deficit hyperactivity disorder (ADHD) and matched normal controls. Thirty-eight boys were observed in their classrooms while engaged in math seatwork. Results revealed that ADHD children were delayed in private speech development in that they engaged in more externalized, self-fuiding and less inaudible, internalized speech than normal youngsters. Several findings suggest that the developmental lag was a consequence of a highly unmanageable attentional system that prevents ADHD children's private speech from gaining efficient mastery over behavior. First, self-guiding speech was associated with greater attentional focus only among the least distractible ADHD boys. Second, the most mature, internalized speech forms were correlated with self-stimulating behavior for ADHD subjects but not for controls. Third, observations of ADHD children both on and off stimulant medication indicated that reducing their symptoms substantially increased the maturity of private speech and its association with motor quiescence and attention to task. Results suggest that the Vygotskian hypothesis of a unidirectional path of influence from private speech to self-controlled behavior should be expanded into a bidirectional model. These findings may also shed light on why treatment programs that train children with attentional deficits in speech-to-self have shown limited efficacy.