Reminiscence bump

The reminiscence bump is the tendency for older adults to have increased recollection for events that occurred during their adolescence and early adulthood.^[1] It was identified through the study of autobiographical memory and the subsequent plotting of the age of encoding of memories to form the lifespan retrieval curve.

The Life Span Retrieval Curve is a graph that represents the number of autobiographical memories encoded at various ages during the life span. The lifespan retrieval curve contains three different parts.^[2] From birth to five years old is a period of childhood amnesia, from 10 to 30 years old is the reminiscence bump and last is a period of forgetting from the end of the reminiscence bump to present time.^[2] The reminiscence bump has been observed on the life span retrieval curve in multiple studies.

The reminiscence bump occurs because memory storage in autobiographical memory is not consistent through time. Rather, memory storage increases during times of changes in the self and in life goals, such as the changes in identity that occur during adolescence.^[3]

Researchers have consistently observed the reminiscence bump, the period of increased memory accessibility in participants' lifespan retrieval curves, and the bump has been reproduced under a range of study conditions.

Adolescence and early adulthood have been described as special times in memory encoding because individuals typically recall a disproportionate number of autobiographical memories from those periods.^[4] The reminiscence bump accounts for this disproportionate number of memories. The reminiscence bump typically occurs between 10 years of age and 30 years of age and it is the period in which individuals produce the most memories during free recall tasks.^[3] Research has suggested that memories are easily accessible from the reminiscence bump because they are memories linked to self-identity.^[5] The memories found within the reminiscence bump significantly contribute to an individual’s life goals, self-theories, attitudes, and beliefs and persist over the life span.^[5] Additionally, life events that occur during the period of the reminiscence bump, such as graduation, marriage, or the birth of a child, are often very novel, thus, making them more memorable.^[6]

A variety of theories have been presented to explain the occurrence of the reminiscence bump. David Rubin, Tamara Rahhal, and Leonard Poon provided three possible explanations of the reminiscence bump: a cognitive account, a narrative/identity account, and a biological/maturational account.^[7]

The cognitive account suggests that memories from early adulthood may be remembered best because they occur during a period of rapid change followed by a period of relative stability.^[4] There is an assumed memory advantage for the novel and distinct events that occur during a period of change which is followed by a period of stability.^[7] The novel events are subject to greater elaborative cognitive processing leading to better encoding of these memories. Moreover, the period of stability that follows increases the stability of the cues for these memories and increases the chances of recall.^[7]

The narrative/identity account suggests that the reminiscence bump occurs because a sense of identity develops during adolescence and early adulthood.^[4] Identity formation provides added motivation for using cognitive processes to ensure recall of these memories.^[4] As well, the events from this period are more likely to be organised into an overall story or view of the self and benefit from advantages of schematic organisation in memory.^[4]

The biological/ maturational account suggests that genetic fitness is improved by having many memories that fall within the reminiscence bump.^[4] Researchers have suggested that the increase in memory during the bump could help cognitive functions required for selecting the best mate.^[4] Also, cognitive capacities are at their optimum from the ages of 10 to 30 and the bump may reflect a peak in cognitive performance^[8]

Following the publishing of the three accounts of the reminiscence bump, Dorthe Bernsten and David Rubin provided an additional theory explaining the occurrence of the reminiscence bump: the life script account. A life script refers to the series of culturally important transitional events that are expected to occur in a certain order at various points during the life span.^[9] A life script typically includes positive experiences such as marriage, the birth of a baby, or buying a house. Events that deviate from the life script are typically sad and traumatic. These events, such as the death of a child, are not culturally expected and often do not show a peak of recall at any specific point during the life span.^[7] Life scripts act as a way to structure memory and lead to the expectation that the happiest and the most important life events form the reminiscence bump. Contrary to the recall of happy events, the recall of sad events remains stable across the life span and does exhibit a bump in recall.^[7]

When studying the reminiscence bump, researchers typically use cue-word techniques. The cue-word technique was first developed by Galton in 1879. Galton found that he could cue memories from his life by observing objects in his environment.^[10] Following this observation, Galton created lists of cue-words to stimulate memory recall in his laboratory. He would record the amount of time required to recall an autobiographical memory related to the cue-word and he would note the distribution of memories over the life span.^[10] By 1974, Crovitz and Schiffman revived Galton's cue-word technique.^[10] Mimicking Galton's technique, the Crovitz-Schiffman cue-word technique requires participants to recall and date autobiographical memories in response to a set of cue-words. Participants are encouraged to share the first memory that pops into their mind when participating in a cue-word task.^[11] The cue-word technique is consistent and reproducible under different conditions such as using different participants or different cue-words. As well, a peak is consistently seen in the dates of the recalled memories that coincides with the reminiscence bump.^[11]

Conway and Haque used the cue-word technique when conducting the study entitled Overshadowing the Reminiscence Bump: Memories of a Struggle for Indepdence. In this study, two groups of Bangladeshi participants recalled and dated autobiographical memories from across their life spans.^[2] To aide memory recall, the researchers presented participants with cue-words such as common locations (restaurants, markets, parks), objects (chair, table, television), positive emotions (happy, joy, cheerful), negative emotions (frustration, pain, sad), and significant others (father, mother, friend).^[2] Participants were instructed to retrieve a memory that reminded them of the cue-word. As well, the participants were instructed to recall memories from across their life span and to recall memories that were at least a year old. Finally, the participants were asked to date each memory to the nearest year and month.^[2] When the dates of the memories were graphed on a life span retrieval curve, a reminiscence bump was observed. A brief description of the results of this study can be found in the Cross-Cultural Studies section found below.

The cued- word technique is one type of recall. Reminiscence bump can also be examined by timeline, fluency recall, or free recall.^[12] In timeline recall, subjects have to indicate important personal events on a timeline. In a fluency test subjects are given a certain time period to recall as many personal events as possible from a certain lifetime. Then, they are given the same time period to recall as many events as possible from another lifetime period. In the free recall method, subjects share personal events. A study conducted by Schlagman et al. (2009) use the free recall method quite well. Researchers wanted to use the free call method to compare involuntary and voluntary memories of young and older children. A researcher would read out 10 words and ask participants to recall as many of the words as possible in no particular order. After participants were informed that they were taking part in a research project on aging and cognition, they were asked to keep a diary on their memory process between two one hour experimental sessions. They were asked to record autobiographical memories as soon as possible using a two-page questionnaire for each memory. Use of this free call method allowed for researchers to keep track of personal thoughts and events.^[12]

Another technique called the Twenty Statements Test (TST) is used in the study of the reminiscence bump. In their study of self-centered memories, Rathborne et al (2008) use the TST to get an empirical measure of self. The method is based on the fact that each individual has multiple selves that can be detected by self-reporting.^[13] Participants taking the TST provide 20 self-concepts that start with “I am…” This will enable the collection of a number of concepts and roles that are important to the definition of self.^[13] According to Hazel Markus’ ideas on self-schemata, there is no unitary structure to self. It is the combination of many self-schemata (including cognitive representations developed from specific autobiographical events) such as “I am mother.”^[14] Depending on stage or context of a person’s life, some self- concepts are stronger than others. This working self-concept combines episodic memories with autobiographical knowledge in autobiographical memory formation.^[15]

Generation identity occurs when an individual recognises that they are part of a particular social subgroup, a cultural generation, and concern themselves with the internalization of external features of the world.^[9] The reminiscence bump occurs during a period of the life span in which identity formation is a primary task. It is also the same period in which an individual adopts their generation identity. Thus, the reminiscence bump reflects both personal identity formation and generation identity formation. The earlier years of the reminiscence bump coincide with the formation of generation identity while the later years coincide with the formation of adult identity.^[9]

The influence of generation identity on the reminiscence bump can be attributed to the idea that all members of the subgroup are likely to have memories of similar types of experiences.^[9] Evidence attesting to the influence of generation identity on the reminiscence bump has been witnessed in populations that have experience with traumatic events. In 1999, Martin Conway and Qi Haque compared younger and older groups of Bangladeshis. The younger group (ages 20–42) showed the usual increase in memories during the reminiscence bump while the older group (ages 46–86) showed a second increase in memories between the ages of 35 and 55. The second bump experienced by the older group corresponded to the period of the Bangladesh Liberation War.^[2] The two generations studied showed similar patterns and timing of memory recall within their own subgroup suggesting that they did have memories of similar experiences such as living through the war or not living through the war. This finding may suggests that each generation has a collective self and individuals belonging to the generation remember personal events and generational events.

Researchers have studied different types of memories in order to find some clues into how the reminiscence bump works and how memories are stored and retrieved. Participants were asked to retrieve memories that were classified as either public or private in order to find differences in terms of when these memories were stored.^[9] Public events are described as political, war/murder, sports/entertainment or news events.^[9] Whereas private events were classified as relationships, births/deaths, work/education, home/leisure, illness and religion.^[9] Public events are events that everyone living at the time know about and are exposed to but private events are part of the individual's experiences which are personal only to them. It was found that when recalling these events, the age the participant when the public event took place was between 10 and 19 and when the private event took place the participant was between 20 and 29.^[9] It is believed that the public events were recalled from an earlier time because this is when individuals are gaining a generation identity and are beginning to identify with certain aspects of society in which they can relate to and believe in.^[9] In doing this, individuals are creating their own belief systems and discussing issues that are important to them. By discussing certain issues, these experiences are being rehearsed, practiced and stored in long-term memory.^[9] Private events are later in the reminiscence bump because this is when individuals are developing intimate relationships.^[9] The private events such as intimate relationships are much more easily stored and recalled because they are unique since they are likely happening without the influences of the family or parent and the independent adult has full responsibility.^[9]

Gender differences have been found in the reminiscence bump for the first 40 years of life. It has been found that men have more positive life events in their thirties and that women have more positive life events in their twenties.^[16] This finding suggests that the timing of important positive life events, such as marriage or employment, differ for men and women.^[16] Most of the major life events start between the age of 15 and 30 but there is a small gender difference shown here with respect to when the event takes place.^[16]

Janssen et al. found a slight gender difference in their study. Women have a slighter early bump than men. The earlier age of the bump in women may be attributed to earlier hormonal changes in adolescence in interaction with sociocultural influences. ^[17]

The reminiscence bump has been studied cross-culturally and has been observed in numerous individuals of various cultural backgrounds and experiences. It is important to consider that the process of remembering occurs in the context of culture and memories found within the reminiscence bump are often congruent with the culture’s goals, values, and belief systems.^[18] The age of occurrence of the reminiscence bump is culturally influenced and reflects the age at which a culture identifies an individual as an adult. In Western societies the reminiscence bump corresponds with adolescence and early adulthood, approximately from the ages of 10 to 30. In Asian cultures the reminiscence bump appears later than in Western cultures because adulthood may not be reached until 30.^[5]

Culture not only influences the age at which the reminiscence bump appears but also the content of the memories found within the bump. Western cultures often value individuality, agency, and distinctiveness and individuals are encouraged to develop and maintain their private beliefs, attitudes, and personality traits. Alternatively, Asian cultures often value group solidarity, communion, and interconnectedness and individuals are encouraged to develop a sense of self that is aligned with social roles, duties, and responsibilities.^[18] The differences in cultural norms expressed by Western and Asian cultures influence the focus of memories. Individuals from Western cultures have memories that cast the individual as the central character of the memory and they often have self focussed autobiographical memories. Individuals from Asian cultures have memories that express a strong group orientation and they often have relation-centred autobiographical memories.^[5]

A study done in 2005 that showed more accurate age results that were dependent on culture and gender. American women and men showed reminiscence bumps at age 13 and 17, respectively, while Dutch participants show a more progressive development of encoding strength around age 15.^[19] Supporting this study, Benson et al. (1992) compared the distribution of memories of participants from Bangladesh, China, England, Japan, and the United States; and, found a greater number of childhood memories among American participants than in other cultural groups.^[17] While the timing of the reminiscence bump is generally thought to be culturally universal, with some minor difference in the period of life from which memories are recalled, there are studies that offer support for the notion that similar life scripts, at least for positive events, might also be found across different cultures. ^[20]

In the Janssen study in 2005, they found evidence for the fact that people younger than 40 years, like people older than 40 years, show a reminiscence bump.^[17] It was hard to notice because of the possibility of the recency effect. But when Janssen et al. examined the encoding values, it showed a progressive increase with participant age around the reminiscence bump for participants older than 50.^[17] This proves that the reminiscence bump is strong for older adults than just adults.

These findings suggest the two processes affect the reminiscence bump phenomenon: (1) Events in adolescence are encoded more strongly than events that occur in other periods of life. (2) Because these events are initially stored more intensely, they will be retrieved more frequently.^[17]

The life script account emphasizes norms and expectations typical of a given culture with regard to the timing of major life events.^[20] The order and timing of the major events may differ depending on the culture. The life script is a representation of the sequence of normative and major life events. Individuals know the culturally shared expectations of the order and timing of life events in a prototypical life, and are also aware of their own timing in relations to those norms.^[20] This is an alternative to theories that explain the process of retrieval and narration of the personal past in terms of cognitive and emotional structures evolving from the life of the individual.^[21] Emotionally charged autobiographical memories across the life span: The recall of happy, sad, traumatic, and involuntary memories.</ref> It suggests that the bum is a product of a particular strategy for searching memory when one’s life is recalled, and assumes that people have an internalized culturally based script of the events that make up and expected, skeletal life course; this script acts as a template for the recall of life events in association with each life phase. ^[22]

A script has two parts: slots and requirements. In the life script, slots are culturally important transitional events that are expected to occur within a circumscribed age span in the life course of individual members of the culture; and, the requirements are that there is a prescribed appropriate age for the event and that the culturally expected event leads to causal sequencing, ascribing a specific order to the event in a series of succeeding events.^[21]

The events in a life script are often positive, celebrated, and normative. It represents and idealized life story. An average life would also include negative events and people would learn from experience. But the life script is handed down form older generations, from stories, and from observations of the behavior of other, typically older, people within the same culture.^[21] Individuals should also remember more during their young adulthood because that era is the time of biological maturation, new experiences, adult identity formation, and major events in life scripts.^[23]

According to Berntsen and Rubin (2004) life scripts have the following ten properties. (1) A life script is semantic knowledge about the expectations in a given culture about life events, not a form of episodic memory for those events. (2) A life scripts is a series of temporally ordered events. (3) A life script can be described in terms of slots and their requirements. (4) Life scripts form a hierarchical arrangement, with transitional events forming a higher order “scene” in which a series of subordinate actions or episodes are nested. (5) Life scripts are used to process stories—here, life stories. (6) The slots and their requirements for life scripts are culturally important transitional events and their culturally sanctioned timing. (7) Because life scripts represent a normative life course, life scripts are not extracted from personal actions in recurrent contexts but are transmitted by tradition. Young people who have lived through only a small part of their lives know the life script of their culture. (8) Life scripts do not represent an average life but instead represent an idealized life, in that many common and important events are left out. (9) Life scripts are distorted from actual lives to favor positive events. (10) Life scripts are distorted from actual lives to favor events expected to occur in the period covered by the bump.

Certain memory tasks work better to try to activate individual’s life scripts. There are two methods that have proved to work best at activating life scripts.

Bernsten and Rubin (2004) believe if the individual is asked to retrieve highly emotional memories from their personal life it is most likely to activate the life script, because most culturally expected transitional events are considered positive and important. They believe that when asked to recall an event from their past, participants first consider when their culture expects the event should happen.^[24] Individuals use this as a reference point for recollection of emotionally charged events and results in a reminiscence bump.^[24]

Another way to activate life scripts is to ask participants to write down the (insert number) most important events that they imagined were highly likely to take place in that prototypical infant’s life.^[24] Then ask participants to answer four questions for each event: prevalence (frequency of occurrence), importance, age at events, valence (emotionally positive or negative), and the types of emotions involved in each event. ^[24]

Berntsen and Rubin’s study confirmed their hypothesis: (1) A high overlap among the events generated by the participants, supporting the assumption of a shared cognitive structure. (2) A correlation between the order in which events were generated and their estimated dates, consistent with life scripts having a temporal structure. (3) A dominance of positive events, consistent with the assumption of an idealized version of life. (4) The age estimates for negative events had higher standard deviation that age estimates for positive and neutral events, consistent with the assumption that negative events have more poorly specified temporal slots than the positive events. (5)The frequency by which events were recorded was predicted strongly by valence and by whether the event fell during the period of the bump. (6) A dominance of culturally sanctioned transitional events, rather than purely biological events, consistent with the claim that mainly culturally sanctioned transitional events go into the life script. (7) The majority of positive events were estimated to occur between the ages of 15 and 30 years, whereas the life span for negative events was relatively flat.

Thomsen et al. suggest some modification of the cultural life script theory: (1) The theory may benefit from explicitly distinguishing between specific transitional events and extended periods of stability. (2) Life script theory proposes that requests for negative events should rarely active the cultural life script, because negative events are often unexpected.^[25] Their study was based on the individual’s unique chapters and specific memories, whereas the cultural life script is a de-personalized and culturally shared knowledge structure.

Markus found preferential access to memories of experiences which corresponds with an individual's sense of self especially in relation to the mechanisms critical to someone's sense of independence or dependence.^[11]

Similarly, McAdams identified individuals with either a strong intimacy motivation or with a distinctive power motivation, and found that the intimacy-motivation group recalled peak experiences with a much higher percentage of intimacy themes, while the power-motivation group tended to recall peak experiences with strong themes of power and satisfaction.^[26]

Generativity refers to nurturing and caring for those things, products, and people that have the potential to outlast the self. Individuals who were judged high in generativity, (i.e. who had a commitment story) were found to recall a higher proportion of events related to aspects of generativity. In contrast, those participants without a prominent disposition towards generativity showed no such bias.^[11]

Woike and colleagues investigated two groups of individuals, those concerned with personal power, achievement, and independence (agentic group) or those concerned with relationships, interdependence, and others (communion group). Argentic types consistently recalled emotional memories of events that involved issues of agency such as those involving mastery, dominance, and humiliation. In contrast, communal types showed a recollection bias for emotional memories featuring others, often significant others, in acts of love and friendship.^[26]

Different emotions have been shown to affect memory. Life events that have stronger emotions attached will be remembered more vividly. In studies looking at emotional events and the reminiscence bump, older adults tend to remember more positive events than younger adults.^[16] Typically, during the reminiscence bump only happy memories and memories of important events are recalled.^[7] It is postulated that sad events are easier to forget because there may be an increased motivation to forget them. Conversely, individuals are more likely to recall and relive happy events because they produced pleasurable memories. A second explanation suggests that remembering positive events can help regulate emotions and even enhance moods.^[16] It is also possible to regulate emotions through remembering negative events and comparing these events to present positive events.^[16] Positive or negative events can also be used to share life experiences with others and compare life events.^[16]

Flashbulb memory occurs when a very vivid memory of a traumatic, emotional, or significant event is recalled.^[27] A significant amount of research has been conducted regarding flashbulb memory. Researchers typically use public events such as the John F. Kennedy assassination and 9/11 as cues when studying flashbulb memories.^[27] Participants are asked to recall very specific information such as where they were, how they felt, and what they were doing when the event was taking place.^[27] Memories of these events are easily recalled and the individual believes their account of the event to be perfectly accurate.^[27]

It has been suggested that flashbulb memories that take place during the reminiscence bump are especially vivid.^[27] These memories have been tested in different ways, including measuring the ability to recall details of the event and the impact of additional cues on the recall of the event.^[27] Denver, Lane and Cherry found that flashbulb memories that took place in the reminiscence bump were exceptionally vivid and easily accessible.^[27] It is suggested that the flashbulb memories encoded during the reminiscence bump are so vivid because the events happened during a time of identity formation and peak brain function.^[27] Additionally, these events are recalled well because they undergo more rehearsal due to their serious nature and frequent discussion.

The impaired functioning of autobiographical memory due to damage or disease can have profound effects on an individual's episodic memory, this can skew an individual's lifespan retrieval curve and influence the presentation of the reminiscence bump. Memories an individual has for personal life events can show a different pattern than the average individual if they have brain damage caused by an event like, an accident, a blow to the head or disease. For these individuals with brain damage, the life span retrieval curve can look different. An example of this is having the reminiscence bump between the age of 5 and 13 rather than 10 to 30 which is the pattern for the average individual.

Brain injury in the frontal lobes can obscure memories and lead to the loss of details. In more extreme cases patients may even construct available autobiographical knowledge into plausible but false memories.^[26] False memories are memories that an individual may produce which have not actually happened but the individual believes that they have and that they are real memories. These individuals can use knowledge that they have about themselves and events that have happened to come up with memories that make sense and could be believed to be true but are simply false memories.

The effect of temporal lobe damage on the reminiscence bump is highly variable as a function of age at the time of injury. This is because patients with damage to the temporal lobes or underlying structures in the limbic system may lose the ability to form new memories, especially if the damage is within the hippocampal formation, while retaining access to at least some memories from before the injury.^[26] Individuals with this type of brain damage are not able to form new memories after the incident that caused the brain damage but they still have access to memories that happened before the brain damage occurred. If the brain damage was present at the age of 10, the individual may not remember anything from between the age of 10 and 30 and have no reminiscence bump.

Those with damage to regions of the brain involved in visual processing, such as the occipital lobes, may develop amnesia. This is because they lose the ability to generate visual images of the past. The episodic content of autobiographical memories is predominantly encoded in the form of visual images and if the ability to generate visual images is compromised or lost then access to specific details of the past held in episodic images is lost as well.^[26] When life events or episodic memories are encoded in the brain, they are in the form of pictures or visual images. When there is damage to areas in the brain used for visual processing, the individual can no longer generate visual pictures or images and they lose information from memory that was already encoded in the form of visual pictures or images. They develop amnesia since they can no longer bring these visual images of the past to mind.

A common psychological phenomenon is the severe clouding of autobiographical memory which results in the overgeneralization of memories.^[26] For instance, clinically depressed individuals, schizophrenic individuals, and those suffering from obsessive compulsive disorder tend to recall many memories that lack detail (clouded) and are much more schematic than typical autobiographical memories. In these instances, a patient asked to recall specific memories of his father could only recall general events such as "walks in the park after Sunday lunch" and was unable to generate a single specific memory of a single walk.^[26]

• Serial position effect

• Human Memory - University of Amsterdam website with autobiographical memory test