Abstract
The present study examined reward and punishment sensitivity using a signal-detection task that gave either equal frequencies of rewards and unequal frequencies of punishments (punishment sensitivity) or unequal frequencies of rewards and equal frequencies of punishments (reward sensitivity). Participants were from a non-clinical population but were screened using scales of adult attention deficit/hyperactive disorder (ADHD) and major depressive disorder (MDD) symptoms. In Experiment 1, participants screened as Adult ADHD displayed significantly higher reward sensitivity than controls, but there were no differences between participants screened as mildly or moderately-or-above depressed and controls. There were no significant differences in punishment sensitivity between Adult ADHD or MDD groups and controls. Experiment 2 modified the task to reduce inherent bias, and scales of reward and punishment sensitivity (BIS/BAS Scales from Carver & White, 1994) were included to compare to the scales of ADHD and MDD. Participants screened with MDD displayed significantly higher reward sensitivity than controls. Their punishment sensitivity was also lower than controls, but this difference was not significant. Participants screened with Adult ADHD displayed higher reward sensitivity, but this difference was not significant. There were no differences between the Adult ADHD participants and controls’ punishment sensitivity. Across both experiments, ADHD and MDD symptoms were correlated, and there was an unexpectedly high numbers of participants screened as Adult ADHD or depressed. Scores on the BIS/BAS scales did not correlate with response bias on the task, and only weakly correlated with ADHD and MDD symptoms. The present study provides some evidence that ADHD and MDD may be related to reward and punishment sensitivity abnormalities; but a clinical sample may be necessary to show strong effects.