The present investigation examined whether higher functioning children with autism would demonstrate impaired response inhibition performance in an emotional go/no-go task, and whether severity of attention-deficit/hyperactivity disorder (ADHD) or autism symptoms correlated with performance. Method: Forty-four children (21 meeting criteria for autism; 23 typically developing controls [TDCs]) completed an emotional go/no-go task in which an emotional facial expression (angry, fearful, happy, or sad) was the go stimulus and a neutral facial expression was the no-go stimulus, and vice versa. Results: The autism group was faster than the TDC group on all emotional go trials. Moreover, the children in the autism group who had the fastest reaction times on emotional go trials were rated as having the greatest number of symptoms (Autism Diagnostic Observation Schedule Social + Communication score), even after accounting for the association with ADHD symptoms. The autism group also made more impulsive responses (i.e., lower d', more false alarms) than the TDC group on all trials. As d' decreased or false alarms increased, so did ADHD symptoms. Hyperactivity/impulsivity symptoms were significantly correlated with false alarms, but inattention symptoms were not. There was not a significant relationship between no-go false alarms and autism symptoms; even after partialing out associations with autism symptoms, the significant correlation between ADHD symptoms and no-go false alarms remained. Conclusion: The present findings support a comorbidity model that argues for shared and independent risk factors, because ADHD and autism symptoms related to independent aspects of emotional go/no-go performance.
