Emotion and memory

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For "emotional memory" in Stanislavski's system of acting, see Affective memory.



Artificially inducing this instinct through traumatic physical or emotional stimuli essentially creates the same physiological condition that heightens memory retention by exciting neuro-chemical activity affecting areas of the brain responsible for encoding and recalling memory.[1][2][3] This memory-enhancing effect of emotion has been demonstrated in a large number of laboratory studies, using stimuli ranging from words to pictures to narrated slide shows,[4][5][6] as well as autobiographical memory studies.[7] However, as described below, emotion does not always enhance memory.

Arousal and valence in memory[edit]


Most studies so far focused on the arousal dimension of emotion as the critical factor contributing to the emotional enhancement effect on memory.[10] Different explanations have been offered for this effect, according to the different stages of memory formation and reconstruction.

Even though the majority of studies have focused on the arousal dimension,[10] a growing body of research is dedicated to the emotional valence dimension and its effects on memory. It has been claimed that this is an essential step towards a more complete understanding of emotion effects on memory.[11] The studies that did investigate this dimension have found that emotional valence alone can enhance memory, that is, nonarousing items with positive or negative valence can be better remembered than neutral items.[12] [13][14]

Emotion and encoding[edit]


Selectivity of attention[edit]


Accordingly, several studies have demonstrated that the presentation of emotionally arousing stimuli (compared to neutral stimuli) results in enhanced memory for central details (details central to the appearance or meaning of the emotional stimuli) and impaired memory for peripheral details.[17][18] Also consistent with this hypothesis are findings of weapon focus effect,[19] in which witnesses to a crime remember the gun or knife in great detail but not other details such as the perpetrator’s clothing or vehicle. In laboratory replications it was found that participants spend a disproportionate amount of time looking at a weapon in a scene, and this looking time is inversely related to the likelihood that individuals will subsequently identify the perpetrator of the crime.[20] Other researchers have suggested arousal may also increase the duration of attentional focusing on the arousing stimuli, thus delaying the disengagement of attention from it.[21] Ochsner (2000) summarized the different findings and suggested that by influencing attention selectivity and dwell time, arousing stimuli are more distinctively encoded, resulting in more accurate memory of those stimuli.[12]

While these previous studies focused on how emotion affects memory for emotionally arousing stimuli, in their arousal-biased competition theory, Mather and Sutherland (2011)[22] argue that how arousal influences memory for non-emotional stimuli depends on the priority of those stimuli at the time of the arousal. Arousal enhances perception and memory of high priority stimuli but impairs perception and memory of low priority stimuli. Priority can be determined by bottom-up salience or by top-down goals.

Prioritized processing[edit]

Emotional items also appear more likely to be processed when attention is limited, suggesting a facilitated or prioritized processing of emotional information.[11] This effect was demonstrated using the attentional blink paradigm[23] in which 2 target items are presented in close temporal proximity within a stream of rapidly presented stimuli.

The typical finding is that participants often miss the second target item, as if there were a “blink” of attention following the first target’s presentation, reducing the likelihood that the second target stimulus is attended. However, when the second target stimulus elicits emotional arousal (a “taboo” word), participants are less likely to miss the target’s presentation,[24] which suggests that under conditions of limited attention, arousing items are more likely to be processed than neutral items.



Emotion and storage[edit]


Others have discovered that memory enhancements for emotional information tend to be greater after longer delays than after relatively short ones.[27][28][29] This delayed effect is consistent with the proposal that emotionally arousing memories are more likely to be converted into a relatively permanent trace, whereas memories for nonarousing events are more vulnerable to disruption.

A few studies have even found that emotionally arousing stimuli enhance memory only after a delay. The most famous of these was a study by Kleinsmith and Kaplan (1963) [27] that found an advantage for numbers paired with arousing words over those paired with neutral words only at delayed test, but not at immediate test. As outlined by Mather (2007),[30] the Kleinsmith and Kaplan effects were most likely due to a methodological confound. However, Sharot and Phelps (2004) [16] found better recognition of arousing words over neutral words at a delayed test but not at an immediate test, supporting the notion that there is enhanced memory consolidation for arousing stimuli.[31] According to these theories, different physiological systems, including those involved in the discharge of hormones believed to affect memory consolidation,[32][33] become active during, and closely following, the occurrence of arousing events.

Another possible explanation for the findings of the emotional arousal delayed effect is post-event processing regarding the cause of the arousal. According to the post stimulus elaboration (PSE) hypothesis,[6] an arousing emotional experience may cause more effort to be invested in elaboration of the experience, which would subsequently be processed at a deeper level than a neutral experience. Elaboration refers to the process of establishing links between newly encountered information and previously stored information.


Emotion and elaboration[edit]

The processes involved in this enhancement may be distinct from those mediating the enhanced memory for arousing items. It has been suggested that in contrast to the relatively automatic attentional modulation of memory for arousing information, memory for non-arousing positive or negative stimuli may benefit instead from conscious encoding strategies, such as elaboration.[11] This elaborative processing can be autobiographical or semantic.

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. Memory formed through autobiographical elaboration is enhanced as compared to items processed for meaning, but not in relation to the self.[36][37]

Since words such as "sorrow" or "comfort" may be more likely to be associated with autobiographical experiences or self-introspection than neutral words such as “shadow”, autobiographical elaboration may explain the memory enhancement of non-arousing positive or negative items. Studies have shown that dividing attention at encoding decreases an individual's ability to utilize controlled encoding processes, such as autobiographical or semantic elaboration.

Thus, findings that participants’ memory for negative non-arousing words suffers with divided attention,[38] and that the memory advantage for negative, non-arousing words can be eliminated when participants encode items while simultaneously performing a secondary task,[39] has supported the elaborative processing hypothesis as the mechanism responsible for memory enhancement for negative non-arousing words.

Emotion and retrieval[edit]

Retrieval is a process of reconstructing past experiences; this phenomenon of reconstruction is influenced by a number of different variables.

Trade-off between details[edit]

Kensinger[40] argues there are two trade-offs: central/peripheral trade-off of details and a specific/general trade-off.

Contextual effects of emotion on memory[edit]


The mood congruence effect[edit]


This effect has been demonstrated for explicit retrieval[41] as well as implicit retrieval.[42]

Mood-state dependent retrieval[edit]

Another documented phenomenon is the mood-state dependent retrieval, a type of context-dependent memory. The retrieval of information is more effective when the emotional state at the time of retrieval is similar to the emotional state at the time of encoding.


Thematic vs. sudden appearance of emotional stimuli[edit]





Memory of felt emotion[edit]

Many researchers use self-report measures of felt emotion as a manipulation check. This raises an interesting question and a possible methodological weakness: are people always accurate when they recall how they felt in the past? [45] Several findings suggest this is not the case. For instance, in a study of memory for emotions in supporters of former U.S. presidential candidate Ross Perot, supporters were asked to describe their initial emotional reactions after Perot’s unexpected withdrawal in July 1992 and again after the presidential election that November.[46]


Another study found that people’s memories for how distressed they felt when they learned of the 9/11 terrorist attacks changed over time and moreover, were predicted by their current appraisals of the impact of the attacks (Levine et al., 2004). 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.[45]

Studies have shown that as episodic memory becomes less accessible over time, the reliance on semantic memory to remember past emotions increases. In one study Levine(2009) [47] primes of the cultural belief of women being more emotional than men had a greater effect on responses for older memories compared to new memories. The long term recall of emotions was more in line with the primed opinions, showing that long term recall of emotions was heavily influenced by current opinions.

Emotion regulation effects on memory[edit]

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. Researchers have begun to examine whether concealing feelings influences our ability to perform common cognitive tasks, such as forming memories, and found that the emotion regulation efforts do have cognitive consequences. In the seminal work on negative affect arousal and white noise, Seidner found support for the existence of a negative affect arousal mechanism through observations regarding the devaluation of speakers from other ethnic origins."[48]

In a study of Richards and Gross (1999) and Tiwari (2013),[49] participants viewed slides of injured men that produced increases in negative emotions, while information concerning each man was presented orally with his slide. The participants were assigned to either an expressive suppression group (where they were asked to refrain from showing emotion while watching the slides) or to a control group (where they were not given regulatory instructions at all). As predicted by the researchers, suppressors showed significantly worse performance on a memory test for the orally presented information. Several related studies have reached similar results. It was demonstrated that the effects of expressive suppression on memory generalize to emotionally positive experiences [50] and to socially relevant contexts.[51]

One possible answer to the question "why does emotion suppression impair memory?" might lay in the self monitoring efforts invested in order to suppress emotion (thinking about the behavior one is trying to control). A recent study [52] found heightened self- monitoring efforts among suppressors relative to control participants.


Emotion-induced forgetting[edit]


Depression and memory[edit]

Memory recall tends to be congruent with one's current mood, with depressed people more likely to recall negative events from the past[56] In addition, depression is often associated with poor memory in general, as outlined here.

Dementia and emotional memory[edit]

Several studies have demonstrated emotional memory enhancement in Alzheimer's patients suggesting that emotional memory enhancement might be used in the daily management of Alzheimer's patients.[57][58][59][60] One study found that objects are recalled significantly better in Alzheimer's patients if they were presented as birthday presents to AD patients.[61]

Aging and emotional memory[edit]

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.[62] However, older adults also show somewhat of a shift towards favoring positive over negative information in memory, leading to a positivity effect.

Emotional memory and sleep[edit]

Emotional memory and sleep has been a well-researched association.[63] Emotional memories are consolidated greater during sleep, rather than neutral memories.[64] Studies have investigated high valence and arousing words, in comparison to neutral words. Sleep enhances the consolidation of the high valence and arousing words and therefore these are remembered more post-sleep. This concept has been demonstrated in many studies using a variety of media such as pictures, film clips and words.[65]

Memories of 'future relevance' are also consolidated greater during sleep. 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.[66] Sleep consolidated these memories of future relevance to a greater extent. Memories that are emotionally significant and relevant for the future are therefore preferentially consolidated during sleep. This can translate to mean that memories that are more meaningful or valuable to a person are consolidated more.

The concept of emotional memory and sleep can be applied to real-life situations e.g. by developing more effective learning strategies. One could integrate the memorization of information that possesses high emotional significance (highly salient) with information that holds little emotional significance (low salience), prior to a period of sleep.

See also[edit]

Notes and references[edit]

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Tiwari, G. K. (2013). Emotional suppression and eyewitness memory. Jigyasa,6(4), 196-203.