Cuthbert, B.N., Schupp, H.T., Bradley, M.M., Birbaumer, N., & Lang, P.J. (2000). Brain potentials in affective picture processing: Covariation with autonomic arousal and affective report. Biological Psychology, 52 (2), 95-111.

Abstract: Evaluates late positive event related potential (ERP) and sustained positive slow waves during affective stimulus exposure, simultaneously recording peripheral physiological changes and affective reports that have been shown to be associated with emotional reactivity. Ss were 37 college students (aged 18-24 yrs). Emotionally arousing picture stimuli evoked scalp-recorded ERPs. A late, slow positive voltage change was observed, which was significantly larger for affective than neutral stimuli. This positive shift began 200-300 ms after picture onset, reached its maximum amplitude ≈1 sec after picture onset, and was sustained for most of a 6-sec picture presentation period. The positive increase was not related to local probability of content type, but was accentuated for pictures that prompted increased autonomic responses and reports of greater affective arousal (e.g. erotic or violent content). These results suggest that the late positive wave indicates a selective processing of emotional stimuli, reflecting the activation of motivational systems in the brain. (PsycINFO Database