ABSTRACT
OBJECTIVE: Performance monitoring was investigated in typically developing (TD) children, children with Autistic Spectrum Disorder (ASD), and Methylphenidate (Mph)-treated and medication-free children with Attention Deficit Hyperactivity Disorder (ADHD). METHODS: Subjects performed a feedback-based learning task. Event-related Potentials (ERPs) time locked to responses and feedback were derived from the EEG. RESULTS: Compared to the TD and ASD groups, the medication-free ADHD group showed a decreased response-locked Error Related Negativity (ERN) and error Positivity (Pe), particularly as learning progressed throughout the task. Compared to the medication-free ADHD group, the Methylphenidate-treated group showed a normalised Pe. All clinical groups showed or tended to show a decreased feedback-locked late positive potential to negative feedback. CONCLUSIONS: The ERPs suggest that medication-free children with ADHD, but not with ASD, have a diminished capacity to monitor their error responses when they are learning by performance feedback. This capacity partially 'normalises' in Mph-treated children with ADHD. Both children with ADHD and children with ASD are suggested being compromised in affective feedback processing. SIGNIFICANCE: This study shows that measuring ERPs of error and feedback processing is a useful method for (1) dissociating ADHD from ASD and (2) elucidating medication effects in ADHD on component processes of performance monitoring.