The activity of emotionally enhanced memory retention can be linked to human evolution; during early development, responsive behavior to environmental events would have progressed as a process of trial and error.
Through evolution, this process of learning became genetically embedded in humans and all animal species in what is known as flight or fight instinct.
One of the most common frameworks in the emotions field proposes that affective experiences are best characterized by two main dimensions: arousal and valence.
[10] Most recently, an intracranial EEG study found that the amygdala triggered more pronounced hippocampal sharp-wave ripples after the encoding of more arousing experiences, which are believed to play a critical role in memory consolidation.
At the encoding level the following mechanisms have been suggested as mediators of emotion effects on memory: Easterbrook's (1959)[16] cue utilization theory predicted that high levels of arousal will lead to attention narrowing, defined as a decrease in the range of cues from the stimulus and its environment to which the organism is sensitive.
Additional support for the prioritized processing hypothesis was provided by studies investigating the visual extinction deficit.
[14][27][28] Others have discovered that memory enhancements for emotional information tend to be greater after longer delays than after relatively short ones.
[32] According to these theories, different physiological systems, including those involved in the discharge of hormones believed to affect memory consolidation,[33][34] become active during, and closely following, the occurrence of arousing events.
Christianson (1992) suggested that the combined action of perceptual, attentional, and elaborative processing, triggered by an emotionally arousing experience, produces memory enhancements of details related to the emotion laden stimulus, at the cost of less elaboration and consolidation of memory for the peripheral details.
Autobiographical elaboration is known to benefit memory by creating links between the processed stimuli, and the self, for example, deciding whether a word would describe the personal self.
Research has shown that this trade-off effect cannot be explained exclusively by overt attention (measured by eye-tracking directed to emotional items during encoding) (Steinmetz & Kensinger, 2013).
Aside from emotional state, mental illness like depression relates to people's ability to recall specific details.
Laney et al. (2003)[48] argued that when arousal is induced thematically (i.e., not through the sudden appearance of a discrete shocking stimulus such as a weapon but rather through involvement in an unfolding event plot and empathy with the victim as his or her plight becomes increasingly apparent), memory enhancements of details central to the emotional stimulus need not come at the expense of memory impairment of peripheral details.
The accompanying audio recording informed participants in the neutral condition that the date went reasonably well, while participants in the emotional condition heard that, as the evening wore on, the man displayed some increasingly unpleasant traits of a type that was derogatory to women, and the embrace at the end of the evening was described as an attempt to sexually assault the woman.
[49] Based on these findings it has been suggested that the dual enhancing and impairing effects on memory are not an inevitable consequence of emotional arousal.
When an emotional experience occurs, the amygdala becomes highly active, signaling the hippocampus to strengthen the encoding and consolidation of these memories.
This process is facilitated by the release of stress hormones and neurotransmitters, which modulate synaptic plasticity and enhance neural connectivity.
[50][51][52] Multiple mechanisms have been proposed to explain this prioritized encoding, including the neuromodulatory effects on plasticity and the dynamic interplay between the amygdala and the hippocampus.
Intracranial EEG studies have shown that the amygdala triggers pronounced hippocampal sharp-wave ripples after encoding emotional experiences, further reinforcing the consolidation of these memories during both awake[11] and sleep.
[53] This coordinated activity between the amygdala and hippocampus ensures that emotionally significant events are prioritized in long-term memory storage, leveraging both immediate neurochemical changes and enduring structural adaptations in neural circuits.
[55] Between the two assessment periods, the views of many supporters changed dramatically as Perot re-entered the race in October and received nearly a fifth of the popular vote.
It appears that memories of past emotional responses are not always accurate, and can even be partially reconstructed based on their current appraisal of events.
An interesting issue in the study of the emotion-memory relationship is whether our emotions are influenced by our behavioral reaction to them, and whether this reaction—in the form of expression or suppression of the emotion—might affect what we remember about an event.
As predicted by the researchers, suppressors showed significantly worse performance on a memory test for the orally presented information.
When gauging the magnitude of cognitive cost, expressive suppression was compared with self-distraction, which was described as simply not trying to think about something.
Fifty-three men's heart rates were measured while looking at unpleasant, neutral, and pleasant pictures and their memory tested two days later.
It was demonstrated that the effects of expressive suppression on memory generalize to emotionally positive experiences[63] and to socially relevant contexts.
[74] The enhancing effects of emotional arousal on later memory recall tend to be maintained among older adults and the amygdala shows relatively less decline than many other brain regions.
In a study by Wilhelm et al., 2011, memories of items that participants knew were needed for the future (for the testing session) were remembered more after sleep.
The concept of emotional memory and sleep can be applied to real-life situations e.g. by developing more effective learning strategies.