EEG repetition effect to high and low arousal emotional stimuli.

In the present EEG study the event-related brain potentials (ERPs) of twenty-four young women were recorded while subjects made old/new recognition judgments about emotionally charged pictures. Pleasant, neutral and unpleasant pictures from the International Affective Picture System (IAPS) were presented twice and differed in emotional intensity (high vs. low arousal). Three time windows were investigated (200-400 ms, 400-600 ms, and 600-100 ms after stimulus onset). Compared to neutral pictures ERP positivity was greater in the early stadium (200-400 ms) for pleasant and unpleased stimuli. Also the positive amplitude of ERPs increased with the intensity of emotional stimuli (i.e. arousal) in all three time ranges and was most pronounced at centro-parietal electrode position with the presence of left hemisphere trend. The old/new effect had a fronto-central bilateral distribution (more present for negative pictures) during 400-600 ms after the stimulus onset and a right anterior distribution in the time window of 600-1000 ms after the stimulus onset for both positive and negative stimuli.