COGNITIVE PSYCHOLOGY

Cognitive Psychology

Abstract

A highly adaptive aspect of human memory is the enhancement of explicit, consciously accessible memory for emotional stimuli. Recent findings from neuroimaging, neuropsychological, drug and neural stimulation studies indicate that emotional stimuli engage specific cognitive and neural mechanisms that enhance explicit memory. Emotional arousal influences memory via factors that act during memory encoding (attention and elaboration) and factors that modulate memory consolidation. Across studies, the amygdala has been consistently implicated as playing a key role in enhancing explicit memory for both pleasant and unpleasant emotional stimuli through modulation of encoding and consolidation processes.

Cognitive Psychology

An impression may be so exciting emotionally as almost to leave a scar upon the cerebral tissues... The primitive impression has been accompanied by an extraordinary degree of attention, either as being horrible or delightful. William James, 1890 ()

It has long been known that emotionally arousing events are more likely to be later recollected than similar, neutral events . An extreme example of this enhancement of memory by emotion is the so-called flashbulb memory: a highly vivid memory for an intensely emotionally engaging event such as hearing the news of the death of a relative or cherished celebrity . From an evolutionary perspective, emotional arousal, whether of an appetitive or aversive nature, signals an event or stimulus that is likely to have both immediate and future relevance to survival and reproductive success. Accordingly, it is adaptive to enhance memory for stimuli that elicit emotional arousal, thus ensuring that important information is available on future occasions .

Are there special mechanisms for emotional memory that are not engaged in the encoding and retrieval of non-emotional memory? Several psychological studies have suggested that the effects of emotional arousal on memory can be explained without needing to postulate special mechanisms for emotional memory . By this view, ordinary cognitive factors such as increased rehearsal, enhanced attention and increased elaboration might be sufficient to account for the memory advantage observed for emotional stimuli. Although such factors clearly play some role in the enhancement of memory for emotional stimuli, specific neural and hormonal mechanisms do exist that enhance memory for emotional stimuli and that are not normally engaged by non-emotional stimuli . Interestingly, these mechanisms appear to operate in part by recruiting the general cognitive mechanisms such as attention and elaborative encoding, the role of which has been emphasized in earlier behavioral studies .

This article examines recent findings regarding the cognitive and neural mechanisms involved in the encoding, consolidation and retrieval of emotional explicit or consciously accessible memory. Relevant data from neuroimaging studies of normal individuals using positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) that concern the key brain structures and mechanisms of emotional memory will be considered, as will data from neuropsychological studies, and from studies of the effects of drugs and of electrical neural stimulation. These findings will be related to a model that accounts for effects of emotion on explicit memory in terms of two classes of effects, both mediated by the amygdala: effects at ...