Abstract: Although most of the theories on attention deficit hyperactivity disorder (ADHD) assumed that deficit in behavioral inhibition was probably the core problem of ADHD, recent studies implied that ADHD patients have aberrant sensitivity to reinforcement, such as rewards and punishment (Sergeant J et al.2000, 2005; Luman M et al. 2005), or emotional control deficit. This aberrant sensibility hypothesis challenges the traditional view on ADHD. However, whether the patients are aberrant sensitive to rewards or to punishment are not clear. Moreover, some relevant studies indicated that Skin conductance responses could reflect their physical arousal while subject responding to cognitive, emotional and social stimulus (Fishbein D et al.2005).
Using two experimental designs, the present study examined the effect of rewards and punishment on affective decision-making on two subtypes of children with attention deficit hyperactivity disorder (ADHD) and normal controls, and recorded their anticipatory Skin conductance recordings (SCRs) as well.
Thirty-eight children between 7 and 12 years old with a clinical diagnosis of ADHD (22 of predominantly inattentive, i.e., ADHD-I; and 16 of combined, i.e., ADHD-C) were compared to 38 normal controls who were matched in age, IQ and the year of education in affective decision-making. Two variations of the Iowa Gambling Task (Bechara et al, 2000) were used, which typically involved two sets of cards in computer. On each of 100 trails, children chose from 1of 2 decks of cards, when turned, which displayed happy and sad faces (experiment 1), or red and green star (experiment 2) corresponding to rewards or punishment respectively, that means won (happy face or red star) or lost (sad face or green star) cartoon cards by each choice. Cards in 1 deck offered more rewards per trail, but were disadvantageous across trails due to occasional large losses; cards in the other deck offered fewer rewards per trial, but were advantageous overall. Different from the previous studies, the intension of rewards and punishment was manipulated in this study.
The results showed that ADHD children were impaired in affective decision-making, and generated lower anticipatory SCRs during the later part of task before choosing from disadvantage card compared with normal controls at the conditions of instant rewards, but were intact at the condition of instant punishment. No significant differences were observed between the two subtypes of ADHD.
The results of which suggested that the children with the two subtypes of ADHD only have aberrant sensibility to rewards, therefore impaired their decision-making. However, they showed the same pattern with normal children when avoiding punishment

Key words: affective decision-making, the Gambling task, Skin conductance recordings, subtypes of ADHD