A flashbulb memory is a highly detailed, exceptionally vivid 'snapshot' of the moment and circumstances in which a piece of surprising and consequential (or emotionally arousing) news was heard.[1] Flashbulb memory is an appropriate name for the phenomenon in that it suggests surprise, an indiscriminate illumination, and brevity. The name is inappropriate as an actual photograph is indiscriminate and preserves everything within its scope. Flashbulb memories, in actuality, are only somewhat indiscriminate and are far from complete.[1] Evidence has shown that although people are highly confident in their memories, the details of the memories can be forgotten.[2]
Flashbulb memories are one type of autobiographical memory. Some researchers believe that there is reason to distinguish flashbulb memories from other types of autobiographical memory because they rely on elements of personal importance, consequentiality, emotion, and surprise.[1][3][4] Others believe that ordinary memories can also be accurate and long lasting if they are highly distinctive, personally significant,[5][6] or repeatedly rehearsed.[7]
Flashbulb memories have six characteristic features: place, ongoing activity, informant, own affect, other affect, and aftermath.[1] Arguably, the principal determinants of a flashbulb memory are a high level of surprise, a high level of consequentiality, and perhaps emotional arousal.
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The term flashbulb memory was coined by Brown and Kulik in 1977 [8] . They formed the special-mechanism hypothesis, which argues for the existence of a special biological memory mechanism that, when triggered by an event exceeding critical levels of surprise and consequentiality, creates a permanent record of the details and circumstances surrounding the experience.[1] Brown and Kulik believed that although flashbulb memories are permanent they are not always accessible from long term memory.[9] The hypothesis of a special flashbulb-memory mechanism holds that flashbulb memories have special characteristics that are different from those produced by “ordinary” memory mechanisms. The representations created by the special mechanism are detailed, accurate, vivid, and resistant to forgetting.[1] Most of these initial properties of flashbulb memories have been debated since Brown and Kulik first coined the term. Ultimately over the years, four models of flashbulb memories have emerged to explain the phenomenon: the photographic model, the comprehensive model, the emotional-integrative model, and importance-driven model; additionally studies have been conducted to test the validity of these models [10].
During extremely arousing and often emotional times, vivid and accurate flashbulb memories are formed. Some common experiences noted are: the deaths of Bob Marley, Elvis Presley, and Kurt Cobain the assassinations of Malcolm X, Rajiv Gandhi, John F. Kennedy, and John Lennon, the disaster involving the Challenger space shuttle, and the occurrences on September 11, 2001[11] Oftentimes, individuals can recall photograph-like memories, and are able to remember exactly what they were doing, for example, or where they were.[12]
The second youngest and thirty-fifth President of the United States, John F. Kennedy, was assassinated on November 22, 1963 in Dallas, Texas. Lee Harvey Oswald was charged with the crime, but never made it to trial, as he was murdered two days after the event. Daniel L. Schacter, a psychology professor at Harvard University, wrote a book in 1996 titled Searching for Memory: The Brain, the Mind, and the Past about the many types of memory, including flashbulb memories. He includes his own experience of flashbulb memory, as it pertains to the recollection of the John F. Kennedy assassination. He could not recall what happened prior to, or immediately following the news, yet reports an image fixed in his mind, in photographic form, of the exact moment in time that he heard of the assassination. When this was written, Schacter acknowledged the thirty-year life of his vivid memory that had not been defeated by time. The memory had yet to erode or degrade.[13]
The December 8, 1980 assassination of John Lennon by Mark David Chapman in New York City was another emotionally arousing event in history, which provokes flashbulb memories for many people. One woman reports her vivid memory of the death announcement, clearly recapturing the moment and accurately describing it down to the reaction of the broadcaster, and her awareness of his change in demeanor while delivering the message. Her flashbulb memory also included her surroundings, and every aspect of her morning routine while getting ready for school[14] Many people were touched by this tragedy, and there are numerous accounts of flashbulb memories regarding the death of John Lennon that include, yet are not limited to, the conversation they had, their state during realization, their surroundings during the hours surrounding the news, the vivid recollection of tears shed, the weather outside, the music on the radio, the feeling of sadness and shock, and the warm encounters with loved ones to cope with the feelings.[15]
On January 28, 1986, seventy-three seconds into flight, the space shuttle named Challenger broke apart and disintegrated over the Atlantic Ocean. Seven crew members were killed in the accident, contributing to the significance of the disaster at that point in time. Flashbulb memories have been implicated in the emotionally arousing event.
Mark Whittington, a writer from Texas, clearly recalled hearing the news of the Challenger space shuttle disaster, and explains his flashbulb memory as "shocking." He recalls being in his vehicle on the way back to his office from a lunch break and, while driving, almost drove off the road before pulling over to continue listening to the tragic news story on the radio. He also recalls the following hours in his day, and the trouble he had concentrating on his work.[16] A study conducted on memories relating to the Challenger incident revealed that the more emotionally aroused one was to the event, and the greater personal linkage that was experienced, the stronger and more significant the vividness and accuracy of the memory became.[17]
On September 11th, 2001, two airliners crashed into the Twin Towers of the World Trade Center in New York City, killing all the people on board and many working in the buildings. A third plane crashed into the Pentagon in Virginia, and a fourth crashed into a field in Pennsylvania. More than six thousand people were injured or killed as a result of these tragic events. Among the many individuals who have memories of this occurrence is Matthew Swulinski, who reported his incredibly vivid account with great intensity. He accurately recalls the exact events as they took place, and forever holds snapshots of the buildings falling to the ground and clouds of dust and smoke surrounding him.[18] One study on the September 11th tragedy, as related to the neural basis of memory and the emotional mechanisms that influence them, suggests that geographic location can also be involved in the strength of flashbulb memories.[19]
Research on flashbulb memories generally shares a common method. Typically, researchers conduct studies immediately following a shocking, public event. [12][7] Participants are first tested within a few days of the event, answering questions via survey or interview regarding the details and circumstances regarding their personal experience of the event. [7] Then groups of participants are tested at for a second time, for example six months, a year, or 18 months later. [20] Generally, participants are divided into groups, each group being tested at different interval. This method allows researchers to observe the rate of memory decay, the accuracy and the content of flashbulb memories.
Many feel that flashbulb memories are not accurate enough to be considered their own category of memory. One of the issues is that flashbulb memories may deteriorate over time, just like everyday memories. Also, it has been questioned whether flashbulb memories are significantly different from everyday memories. A number of studies suggest that flashbulb memories are not especially accurate, but that they are experienced with great vividness and confidence.[21][22] Such research focuses on identifying reasons why flashbulb memories are more accurate than everyday memories. It has been documented that importance of an event, the consequences involved, how distinct it is, personal involvement in the event, and proximity increase the accuracy of recall of flashbulb memories.[23]
It has been argued that flashbulb memories are not very stable over time. A study conducted on the recollection of flashbulb memories for the Challenger Space Shuttle disaster sampled two independent groups of subjects on a date close to the disaster, and another eight months later. Very few subjects had flashbulb memories for the disaster after eight months. Considering only the participants who could recall the source of the news, ongoing activity, and place, researchers reported that less than 35% had detailed memories.[24] Another study examining participants' memories for the Challenger Space Shuttle explosion found that although participants were highly confident about their memories for the event, their memories were not very accurate three years after the event had occurred.[7] A third study conducted on the O.J. Simpson murder case found that although participants' confidence in their memories remained strong, the accuracy of their memories declined 15 months after the event, and continued to decline 32 months after the event.[25]
However, other studies still show that the uniqueness of flashbulb memories is due to the confidence of those who remember them. A study conducted on the bombing in Iraq and a contrasting ordinary event showed no difference for memory accuracy over a year period; however, participants showed greater confidence when remembering the Iraqi bombing than the ordinary event despite no difference in accuracy.[26] Likewise, when memories for the 9/11 World Trade Center attack were contrasted with everyday memories, researchers found that after one year, there was a high, positive correlation between the initial and subsequent recollection of the 9/11 attack. This indicates very good retention, compared to a lower positive correlation for everyday memories.[27] Participants also showed greater confidence in memory at time of retrieval than time of encoding.
Some studies indicate that flashbulb memories are not more accurate than other types of memories.[28] It has been reported that memories of high school graduation or early emotional experiences can be just as vivid and clear as flashbulb memories. Undergraduates recorded their three most vivid autobiographical memories. Nearly all of the memories produced were rated to be of high personal importance, but low national importance. These memories were rated as having the same level of consequentiality and surprise as memories for events of high national importance. This indicates that flashbulb memories may just be a subset of vivid memories and may be the result of a more general phenomenon. [28]
Flashbulb memory has always been classified as a type of autobiographical memory, which is memory for one's everyday life events. Emotionally neutral autobiographical events, such as a party or a barbecue, were contrasted with emotionally arousing events that were classified as flashbulb memories. Memory for the neutral autobiographical events was not as accurate as the emotionally arousing events of Princess Diana's death and Mother Teresa's death. Therefore, flashbulb memories were more accurately recalled than everyday autobiographical events.[29] In some cases, consistency of flashbulb memories and everyday memories do not differ, as they both decline over time. Ratings of vividness, recollection and belief in the accuracy of memory, however, have been documented to decline only in everyday memories and not flashbulb memories.[22]
Brown and Kulik emphasized that importance is a critical variable in flashbulb memory formation. In a study conducted by Brown and Kulik, news events were chosen so that some of them would be important to some of their subjects, but not to others. They found that when an event was important to one group, it was associated with a comparatively high incidence of flashbulb memories. The same event, when judged lower on importance by another group, was found to be associated with a lower incidence of flashbulb memory.[1] The retelling or rehearsal of personally important events also increases the accuracy of flashbulb memories. Personally important events tend to be rehearsed more often than non-significant events. A study conducted on flashbulb memories of the Loma Prieta earthquake found that people who discussed and compared their personal stories with others repeatedly had better recall of the event compared to Atlanta subjects who had little reason to talk about how they had heard the news. Therefore, the rehearsal of personally important events can be important in developing accurate flashbulb memories.[21] There has been other evidence that shows that personal importance of an event is a strong predictor of flashbulb memories. A study done on the flashbulb memory of the resignation of the British prime minister, Margaret Thatcher, found that the majority of UK subjects had flashbulb memories nearly one year after her resignation. Their memory reports were characterized by spontaneous, accurate, and full recall of event details. In contrast, a low number of non-UK subjects had flashbulb memories one year after her resignation. Memory reports in this group were characterized by forgetting and reconstructive errors. The flashbulb memories for Margaret Thatcher's resignation were, therefore, primarily associated with the level of importance attached to the event.
It was proposed that the intensity of initial emotional reaction, rather than perceived consequentiality, is a primary determinant of flashbulb memories. Flashbulb memories of the 1981 assassination attempt on President Reagan were studied, and it was found that participants had accurate flashbulb memories seven months after the shooting. Respondents reported flashbulb memories, despite low consequentiality ratings. This study only evaluated the consequence of learning about a flashbulb event, and not how the consequences of being involved with the event affects accuracy. Therefore, some people were unsure of the extent of injury, and most could only guess about the eventual outcomes.[30] Two models of flashbulb memory state that the consequences of an event determines the intensity of emotional reactions. The Importance Driven Emotional Reactions Model indicates that personal consequences determine intensity of emotional reactions. The consequence of an event is a critical variable in the formation and maintenance of a flashbulb memory. These propositions were based on flashbulb memories of the Marmara earthquake.[31] The other model of flashbulb memory, called the Emotional-Integrative model, proposes that both personal importance and consequentiality determine the intensity of one's emotional state.[32] Overall, the majority of research found on flashbulb memories demonstrates that consequences of an event play a key role in the accuracy of flashbulb memories.
Some experiences are unique and distinctive, while others are familiar, commonplace, or are similar to much that has gone on before. Distinctiveness of an event has been considered to be a main contributor to the accuracy of flashbulb memories.[33] The accounts of flashbulb memory that have been documented as remarkably accurate have been unique and distinctive from everyday memories. It has been found that uniqueness of an event can be the best overall predictor of how well it will be recalled later on. In a study conducted on randomly sampled personal events, subjects were asked to carry beepers that went off randomly. Whenever the beeper sounded, participants recorded where they were, what they were doing, and what they were thinking. Weeks or months later, the participants' memories were tested. The researchers found that recall of action depends strongly on uniqueness.[33] Similar results have been found in studies regarding distinctiveness and flashbulb memories; memories for events that produced flashbulb memories, specifically various terrorist attacks, had high correlations between distinctiveness and personal importance, novelty, and emotionality.[34] It has also been documented that if someone has a distinctive experience during a meaningful event, then accuracy for recall will increase. During the 1989 Loma Prieta earthquake, higher accuracy for the recall of the earthquake was documented in participants who had distinctive experiences during the earthquake, often including a substantial disruption in their activity.[21]
It has been documented that people that are involved in a flashbulb event have more accurate recollections compared to people that were not involved in the event. Recollections of those who experienced the Marmara earthquake in Turkey had more accurate recollections of the event than people who had no direct experience. In this study, the majority of participants in the victim group recalled more specific details about the earthquake compared to the group that was not directly affected by the earthquake, and rather received their information about it from the news.[31] Another study compared Californians' memories of an earthquake that happened in California to the memories of the same earthquake formed by people who were living in Atlanta. The results indicated that the people that were personally involved with the earthquake had better recall of the event. Californians' recall of the event were much higher than Atlantans', with the exception of those who had relatives in the affected area, such that they reported being more personally involved.[21]
A study conducted on the September 11th terrorist attacks demonstrates that proximity plays a part in the accuracy of recall of flashbulb memories. Three years after the terrorist attacks, participants were asked to retrieve memories of 9/11, as well as memories of personally selected control events from 2001. At the time of the attacks, some participants were in the downtown Manhattan region, closer to the World Trade Center, while others were in Midtown, a few miles away. The participants who were closer to downtown recalled more emotionally significant detailed memories than the Midtown participants. When looking solely at the Manhattan participants, the retrieval of memories for 9/11 were accompanied by an enhancement in recollective experience relative to the retrieval of other memorable life events in only a subset of participants who were, on average, two miles from the World Trade Center (around Washington Square) and not in participants who were, on average, 4.5 miles from the World Trade Center (around the Empire State Building). Although focusing only on participants that were in Manhattan on 9/11, the recollections of those closer to the World Trade Center were more vivid than those who were farther away. The downtown participants reported seeing, hearing, and even smelling what had happened.[12] Personal involvement in, or proximity to, a national event could explain greater accuracy in memories because there could be more significant consequences for the people involved, such as the death of a loved one, which can create more emotional activation in the brain. This emotional activation in the brain has been shown to be involved in the recall of flashbulb memories.
Although people of all ages experience flashbulb memories, different demographics and ages can influence the strength and quality of a flashbulb memory.
In general, younger adults form flashbulb memories more readily than older adults.[35] One study examined age related differences in flashbulb memories: participants were tested for memory within 14 days of an important event and then retested for memory of the same event 11 months later. Even 11 moths after the event occurred nearly all the younger adults experienced flashbulb memories, but less than half of the older adults met all the criterion of a flashbulb memory. Younger and older adults also showed different reasons for recalling vivid flashbulb memories. The main predictor for creating flashbulb among younger adults was emotional connectedness to the event, whereas older adults relied more on rehearsal of the event in creating flashbulb memories.[36] Being emotionally connected was not enough for older adults to create flashbulbs; they also needed to rehearse the event over the 11 months to remember details. Older adults also had more difficulty remembering the context of the event; the older adults were more likely to forget with whom they spoke and where events took place on a daily basis. [37] If older adults are significantly impacted by the dramatic event, however, they could form flashbulb memories that are just as detailed as younger adults form. Older adults that were personally impacted by or in close proximity to September 11th recalled memories that did not differ in detail from those of younger adults. [38][39]
Generally the factors that influence flashbulb memories are considered to be constant across cultures. Tinti et al. (2009) conducted a study on memories of Pope John Paul II’s death amongst Polish, Italian, and Swiss Catholics.[40] The results showed that personal involvement was most important in memory formation, followed by proximity to the event.
Flashbulb memories differ among cultures with the degree to which certain factors influence the vividness of flashbulb memories. For example, Asian cultures de-emphasis individuality; therefore Chinese and Japanese people might not be as affected by the effects of personal involvement on vividness of flashbulb memories. A study conducted by Kulkofsky, Wang, Conway, Hou, Aydin, Johnson, and Williams (2011) investigated the formation of flashbulb memories in 5 countries: China, the United Kingdom, the United States, Germany, and Turkey. Overall participants in the United States and the United Kingdom reported more memories in a 5 minutes span than participants from Germany, Turkey, and China. This could simply be due to the fact that different cultures have different memory search strategies. In terms of flashbulb memories, Chinese participants were less affected by all factors related to personal closeness and involvement with the event. There were also cultural variations in effects of emotional intensity and surprise.[40]
Although not much research has been done on gender and flashbulb memories, one study notes the existence of gender effects on the presence of various factors which contribute to flashbulb memories. Researchers had Israeli University students complete questionnaires regarding their memories for various terrorist attacks. Men rated the distinctiveness of their flashbulb-producing event significantly higher than females did. Additionally, men had memories with significantly more detail than women. Women however, reported significantly higher rates of emotional reactivity.[34] Unfortunately, it is unclear how generalizable these findings are as they are the results from only one study.
Can flashbulb memories be improved? A number of studies have found that flashbulb memories are formed immediately after a life changing event happens or when news of the event is relayed.[41] Although additional information about the event can then be researched or learned, the extra information is often lost in memory due to different encoding processes. A more recent study, examining effects of the media on flashbulb memories for the September 11th, 2001 attacks, shows that extra information may help retain vivid flashbulb memories. Although the researchers found that memory for the event decreased over time for all participants, looking at images had a profound effect on participants memory. Those who said they saw images of the September 11th attacks immediately retained much more vivid images 6-months later than those who said they saw images hours after they heard about the attacks. The latter participants failed to encode the images with the original learning of the event. Thus, it may be the images themselves that lead some of the participants to recall more details of the event. Graphic images may make an individual associate more with the horror and scale of a tragic event and hence produce a more elaborate encoding mechanism.[42] Furthermore, perhaps looking at images may help individuals retain vivid flashbulb memories months, and perhaps even years, after an event occurs.
The special-mechanism hypothesis has been the subject of considerable discussion in recent years, with some authors endorsing the hypothesis and others noting potential problems.This hypothesis divides memory processes into different categories, positing that different mechanisms underlie flashbulb memories. Yet many argue that flashbulb memories are simply the product of multiple, unique factors coalescing.[43]
Data concerning people's recollections of the Reagan assassination attempt provide support for the special-mechanism hypothesis.[30] People had highly accurate accounts of the event and had lost very few details regarding the event several months after it occurred. Additionally, an experiment examining emotional state and word valence found that people are better able to remember irrelevant information when they are in a negative, shocked state. [44] There is also neurological evidence in support of a special mechanism view. Emotionally neutral autobiographical events, such as a party, were compared with two emotionally arousing events: Princess Diana's death, and Mother Teresa's death. Long-term memory for the contextual details of an emotionally neutral autobiographical event was significantly related to medial temporal lobe function and correlated with frontal lobe function, whereas there was no hint of an effect of either medial temporal lobe or frontal lobe function on memory for the two flashbulb events. These results indicate that there might be a special neurobiological mechanism associated with emotionally arousing flashbulb memories.[29]
Studies have shown that flashbulb memories can result from non-surprising events,[7] such as the first moon landing,[45] and also from non-consequential events. While Brown and Kulik defined flashbulb memories as memories of first learning about a shocking event, they expand their discussion to include personal events in which the memory is of the event itself. Simply asking participants to retrieve vivid, autobiographical memories has been shown to produce memories that contain the six features of flashbulb memories.[28] Therefore, it has been proposed that such memories be viewed as products of ordinary memory mechanisms.[5] Moreover, flashbulb memories have been shown to be susceptible to errors in reconstructive processes, specifically systematic bias.[46] It has been suggested that flashbulb memories are not especially resistant to forgetting.[7][21][22] A number of studies suggest that flashbulb memories are not especially accurate, but that they are experienced with great vividness and confidence.[21][22] Therefore, it is argued that it may be more precise to define flashbulb memories as extremely vivid autobiographical memories. Although they are often memories of learning about a shocking public event, they are not limited to such events, and not all memories of learning about shocking public events produce flashbulb memories.[47]
Brown and Kulik proposed the term flashbulb memory, along with the first model of the process involved in developing what they called flashbulb accounts.[1] The photographic model proposes that in order for a flashbulb account to occur in the presence of a stimulus event, there must be, a high level of surprise, consequentiality, and emotional arousal. Specifically, at the time in which an individual first hears of an event, the degree of unexpectedness and surprise is the first step in the registration of the event. The next step involved in registration of flashbulb accounts is the degree of consequentiality, which in turn, triggers a certain level of emotional arousal. Brown and Kulik described consequentiality as the things one would imagine may have gone differently if the event hadn’t occurred, or what consequences the event had on an individual’s life.[1] Furthermore, Brown and Kulik believed that high levels of these variables would also result in frequent rehearsal, being either covert (“always on the mind”) or overt (ex. talked about in conversations with others). Rehearsal, which acts as a mediating process in the development of a flashbulb account, creates stronger associations and more elaborate accounts. Therefore, the flashbulb memory becomes more accessible and vividly remembered for a long period of time.[1]
Some researchers recognized that previous studies of flashbulb memories are limited by the reliance on small sample groups of few nationalities, thus limiting the comparison of memory consistency across different variables. The comprehensive model was born out of similar experimentation as Brown and Kulik's, but with a larger participant sample. One major difference between the two models is that the Photographic Model follows more of a step-by-step process in the development of flashbulb accounts, whereas the Comprehensive Model demonstrates an interconnected relationship between the variables. Specifically, knowledge and interest in the event affects the level of personal importance for the individual, which also affects the individual’s level of emotional arousal (affect). Furthermore, knowledge and interest pertaining to the event, as well as the level of importance, contribute to the frequency of rehearsal. Therefore, high levels of knowledge and interest contribute to high levels of personal importance and affect, as well as high frequency of rehearsal. Finally, affect and rehearsal play major roles in creating associations, thus enabling the individual to remember vivid attributes of the event, such as the people, place, and description of the situation.[48]
An Emotional-Integrative Model of flashbulb memories integrates the two previously discussed models the Photographic Model and the Comprehensive Model. [32] Similar to the Photographic Model, the Emotional-Integrative Model states that the first step toward the registration of a flashbulb memory is an individual’s degree of surprise associated with the event. This level of surprise triggers an emotional feeling state, which is also a result of the combination of the level of importance (consequentiality) of the event to the individual, and the individual’s affective attitude. The emotional feeling state of the individual directly contributes to the creation of a flashbulb memory. To strengthen the association, thus enabling the individual to vividly remember the event, emotional feeling state and affective attitude contribute to overt rehearsal (mediator) of the event to strengthen the memory of the original event which, in turn, determines the formation of a flashbulb memory.[32] According to the Emotional-Integrative model flashbulb memories can also be formed for expected events.[49] The formation of flashbulb memories in this case depends greatly on a high emotional relationship to the event and rehearsal of the memory.[50]
This model emphasizes that personal consequences determine intensity of emotional reactions.[31] These consequences are, therefore, critical operators in the formation and maintenance of flashbulb memories. This model was based on whether traumatic events were experienced or not during the Marmara earthquake. According to the findings of this study, the memories of the people who experienced the earthquake were preserved as a whole, and unchanged over time. Results of the re-test showed that the long-term memories of the victim group are more complete, more durable and more consistent than those of the comparison group. Therefore, based on this study, a new model was formed that highlights that consequences play a very large role in the formation of flashbulb memories.[31]
As discussed previously, flashbulb memories are engendered by a highly emotional, surprising events. How are these memories different from memories for traumatic events? The answer is stress. Traumatic events involve some element of fear or anxiety. While flashbulb memories can include components of negative emotion, these elements are generally absent.
There are though, some similarities between the two and flashbulb memories. During a traumatic event, high arousal can increase attention to central information leading to increased vividness and detail--similar to flashbulb memory. Another similar characteristic is that memory for traumatic events is enhanced by emotional stimuli. However, the largest difference between the nature of flashbulb memories and traumatic memories is the amount of information regarding unimportant details that will be encoded in the memory of the event. In high-stress situations, arousal dampens memory for peripheral information—such as context, location, time, or other less important details.[51]
Laboratory studies have related specific neural systems to the influence of emotion on memory. Cross-species investigations have shown that emotional arousal causes neurohormonal changes, which engage the amygdala. The amygdala modulates the encoding, storage, and retrieval of episodic memory.[52][53][54][55][19] These memories are later retrieved with an enhanced recollective experience,[19][56] similar to the recollection of flashbulb memories. The amygdala, therefore, may be important in the encoding and retrieval of memories for emotional public events. Since the role of the amygdala in memory is associated with increased arousal induced by the emotional event,[57] factors that influence arousal should also influence the nature of these memories. The constancy of flashbulb memories over time varies based on the individual factors related to the arousal response, such as emotional engagement [30][58] and personal involvement with the shocking event.[21] The strength of amygdala activation at retrieval has been shown to correlate with an enhanced recollective experience for emotional scenes, even when accuracy is not enhanced.[19] Memory storage is increased by endocrine responses to shocking events; the more shocking an individual finds an event, the more likely a vivd flashbulb memory will develop.
There has been considerable debate as to whether unique mechanisms are involved in the formation of flashbulb memories, or whether ordinary memory processes are sufficient to account for memories of shocking public events. Sharot et al. found that for individuals who were close to the World Trade Center, the retrieval of 9/11 memories engaged neural systems that are uniquely tied to the influence of emotion on memory. The engagement of these emotional memory circuits is consistent with the unique limbic mechanism that Brown and Kulik[1] suggested. These are the same neural mechanisms, however, engaged during the retrieval of emotional stimuli in the laboratory.[19] The consistency in the pattern of neural responses during the retrieval of emotional scenes presented in the laboratory and flashbulb memories suggests that even though different mechanisms may be involved in flashbulb memories, these mechanisms are not unique to the surprising and consequential nature of the initiating events.
Evidence indicates the importance of the amygdala in the retrieval of 9/11 events, but only among individuals who personally experienced these events.[19] The amygdala’s influence on episodic memory is explicitly tied to physiological arousal.[57] Although simply hearing about shocking public events may result in arousal, the strength of this response likely varies depending on the individual’s personal experience with the events.
Flashbulb memory research tends to focus on public events that have a negative valence. There is a shortage on studies regarding personal events such as accidents or trauma. This is due to the nature of the variables needed for flashbulb memory research: the experience of a surprising event is hard to manipulate. Additionally, little research has been done on gender differences and flashbulb memory, although it exists for general memory.