Lots of studies suggest that children with ADHD have deficits in facial emotion recognition, especially for the negative emotion. But there were arguments for this deficit is a secondary problem due to the general attention impairment in ADHD, or a specific social cognitive processing to ADHD. The objectives of this study are to investigate that association between the deficits in facial emotion recognition and the emotional attention processing in ADHD. In this study, the investigators use the emotion attentional bias and emotional go / no go paradigm to answer this question.