This study tested a new hypothesis on Gray's Reinforcement Sensitivity Theory (RST) proposed by Corr (2002) which postulates that both the behavioural inhibition system (BIS) and the behavioural activation system (BAS) have the potential to influence both reward-mediated and punishment-mediated behaviours. This new hypothesis was tested using affective modulation of the mismatch negativity (MMN) obtained through auditory event-related potentials. The MMN was obtained from 61 subjects while they read or watched emotionally negative, positive, and neutral pictures. Participants were assigned to either a "low" or "high" group in Sensitivity to Punishment (SP- or SP+) and in Sensitivity to Reward (SR- or SR+), according to their scores on the Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ). In line with the joint subsystems hypothesis results show that: (1) SP+ subjects displayed a higher MMN peak over frontal and central scalp sites in the presence of unpleasant slides as compared to positive or neutral ones, but this effect was stronger in SP+/SR- participants, indicating that sensitivity to reward antagonizes this BIS-mediated response; and (2) SR- participants displayed an enhanced MMN peak in the presence of unpleasant (compared to pleasant, reading, and neutral) slides. The present results are discussed in light of Gray's classic RST and the new joint subsystems hypothesis. (C) 2004 Elsevier Ltd. All rights reserved.
