The effects of emotional intensity on ERP correlates of recognition memory

The effects of negative emotional intensity on memory-related brain activity were tested by using human scalp event-related potentials (ERP). A neural index of memory function--the electrophysiological 'Old-New' effect--was obtained from participants undertaking a memory recognition test of previously studied ('old') and unstudied ('new') pictures of variable levels of negative emotional intensity. The magnitude of the old-new effect was compared across four different levels of linearly increasing stimulus emotional intensity. Results revealed an inverted-U-shaped effect of emotional intensity on the magnitude of ERP old-new differences starting at 300 ms after stimulus onset. These results suggest that moderate negative emotions can enhance memory brain function, whereas extreme levels of emotional intensity have the potential of inhibiting memory function. Results are discussed in terms of their implications for neurobiological and psychological models of emotion-memory interactions.