Changing a response set in normal development and in ADHD children with and without tics.

The current study was designed to provide a rigorous investigation of the locus of task-inappropriate (impulsive) responding in ADHD children with and without tics. For this purpose we used a variant of Sternberg's (1969) response bias task. The task measures a set of mental operations, namely, preparing a planned response, carrying out or stopping a planned response, and preparing to execute an alternative response. In the first study, we determined the effect of age in a normal sample. As expected, task performance improved as a function of age. Younger children had problems changing a response set. In the second experiment, we compared ADHD children with and without tics with normal children. Unexpectedly, the noticeable task inefficiency of the patient groups was not related to (a) a hasty scan of the display, (b) an inability to change response set, or (c) a speed-accuracy trade-off. Implications for and a discussion about the response inhibition hypothesis in ADHD are discussed.