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Abstract:
Abstract: We investigated the relationship between two
event-related potential (ERP) phenomena. First, ERPs for pleasant
and unpleasant pictures tend to be more positive than for neutral
pictures (emotion effect). Second, ERPs for items that are
subsequently remembered tend to be more positive than ERPs for
those that are subsequently forgotten (Dm effect). Since, emotional
pictures are usually better remembered than neutral pictures, the
positivity for emotional pictures could reflect a Dm effect.
Alternatively, emotion and Dm effects could reflect different
phenomena. In the present experiment, ERPs were recorded while
subjects rated the pleasantness of pleasant, unpleasant, and
neutral pictures. Subjects performed later a free recall test for
information in the pictures. Preliminary analyses yielded three
main results. First, the emotion effect appeared earlier (500-700
ms) over posterior scalp regions and later (700-1200) on central
electrodes. Second, the emotion on central electrodes occurred
earlier for pleasant than for unpleasant pictures. Finally, the Dm
effect was modulated by emotion: it was larger for pleasant and
unpleasant pictures than for neutral pictures. This pattern
paralleled free recall performance, which was better for emotional
than for neutral pictures. These results suggest that the later
central component of the emotion effect overlaps with the Dm
effect, whereas the early posterior component of the emotion effect
and the differences between pleasant and unpleasant pictures could
reflect different phenomena.
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