Yearning for Yesterday: The Mechanisms and Applications of Nostalgia
Niah Dang
Illustrations by Sneha Das
The Enduring Magic of Memories
Remember that perfect summer day, when the sun warmed your skin and the wind rustled through your hair? Envision your childhood best friend, the person you grew up with who is a part of your fondest memories. Recall those early days spent laughing so hard your stomach hurt on the elementary school playground and, much later, crying on their shoulder after losing your first love. Memories can elicit this feeling of nostalgia, which is often categorized as wistful affection and sentimental yearning for the past [1]. Nostalgia can evoke both positive and negative emotions; remembering can induce a wave of happiness that is quickly followed by a bittersweet or melancholic longing [2]. Nostalgia is generally prompted by meaningful memories, past close relationships, and childhood experiences, with sensory stimuli being a common trigger [3]. For some, the smell of freshly cut grass may bring back memories of playing outside on their childhood home’s front lawn, promoting a yearning for the past [4]. For others, it’s the taste of their grandmother’s golden pie that ‘tastes like home’ [5]. Whether nostalgia is prompted by past social ties, smells, tastes, music, or nature, most of us are familiar with its ambivalent experience [1].
Unlocking the Memory Vault: The Intricacies of Semantic and Episodic Memories
Before examining what makes a memory nostalgic, let’s consider how our ‘normal’ memories function. The memory of general concepts — usually separated from personal experience — is known as semantic memory [6]. Think of semantic memory as an encyclopedia of knowledge or facts [7]. These are things you learned in school, such as the days of the week [6]. On the other hand, episodic memories are attached to personal experiences that occurred at a specific time and place [7]. How did you spend your childhood birthdays? What’s the happiest memory you have of the past year? Maybe you have a vivid memory of the cotton candy machine at your fifth birthday party or when you went on a big trip to the waterpark with your entire family. Such memories are a recollection of personal experiences through an autobiographical lens [7]. When semantic or episodic memories are encoded in the brain, they form a physical unit called an engram [8]. During engram formation, your brain takes in information about a situation — sights, sounds, smells, tastes, emotions, and language — and assigns value to whatever you perceive or pay attention to [9]. Your brain then weaves together all the neural activity occurring at this time to form a pattern of associated connections, also known as a neural circuit, and stores it as an engram [10]. Notably, the more important or personally significant the information from the situation is, the stronger the engram will be and the easier the memory will be to recall as a result [11]. Later — whether that be the next day or years down the line — when a familiar stimulus reactivates the engram, an electrical signal is produced by the neurons that compose the engram, allowing you to recall stored information [8]. Engrams allow short-term memories to be encoded into stable long-term memories that you retain far in the future [9].
Although engrams represent both semantic and episodic memories in the brain, remembering your amazing algebra teacher is quite different from remembering the Pythagorean theorem. Because of the personal significance of episodic memories, they are easier to recall than general knowledge, such as facts and theorems [12]. Different brain structures are responsible for the processing of different types of memories: the hippocampus mediates the storage of episodic memories, while the neocortex manages the storage of semantic memories [13]. When it comes to memory storage, the hippocampus is comparable to a filing cabinet, which stores and organizes individual experiences in memory [14]. In fact, the hippocampus plays a key role in encoding the patterns of neural firing that occur as memories are formed, distributing and integrating information throughout the network of neurons that are involved in the recollection of that experience [7]. When the hippocampus encodes episodic memories, it stores the details of personal experiences [15]. On the other hand, the neocortex can be thought of as a textbook and is involved in processes such as cognition, language, and consciousness [16]. The neocortex is useful in gathering representations of structured knowledge, such as the rules of a game [15]. But how do we go about daunting tasks like studying for a test or trying to memorize large amounts of information? Most of us know that repetition is key in encoding and storing large amounts of information: reading something once probably won’t result in a comprehensive understanding of the material [17]. We need repetition because the neocortex is known to be a ‘slow learner,’ where many encodings of the same information are necessary to achieve long-term storage, substantiating its role in semantic memory [17]. In essence, the intricate roles of the hippocampus and the neocortex underscore the dynamic nature of memory formation and storage in the human brain.
A Mental Photo Album: Nostalgic Memories in the Brain
The aforementioned processes are how all memories are encoded: semantic, episodic, and nostalgic [8]. Though a nostalgic memory has many of the same characteristics as an episodic memory — since it too originates from personal experiences and carries an emotional component — nostalgic memories can be thought of as a unique form of episodic memory [1]. Consider a memory that is solely episodic, such as a typical day sitting through your boring class lecture. There isn’t a huge emotional component to this memory; however, that could change. Imagine that years down the line, you begin to reminisce about your formative college years. You feel nostalgic for the crazy adventures with your friends in addition to the mundane days spent in class daydreaming about the future. Your once largely episodic memory has now morphed to include a nostalgic component. Interestingly, this may have to do with the time period in which the memory takes place, as memories from adolescence and early adulthood are more strongly encoded and prone to becoming nostalgic [18]. Nostalgic memories uniquely draw a co-occurrence of positive and negative emotions when the memories are recalled, often with more positive than negative feelings — a complex mix of emotions not elicited by episodic memories [19, 20]. Nostalgia includes feelings of happiness and pleasure, but more importantly, involves a melancholy component of longing for a time that has since passed [19, 20, 21]. Furthermore, nostalgia comprises more than just a general recall of the details of important life events; it also involves ‘mental time travel,’ where detailed imagery associated with the event is recalled as if you are re-experiencing the event for the first time again [21, 22]. Imagine walking past the park where you used to watch the sunset every night of the summer with your best friend. You spot the rock you used to sit on, the fond location of many deep conversations, and begin to reminisce about your youth. Through a process called pattern completion, the sight of the place where you spent so much of your childhood reactivates the same pattern of neural activity that was triggered when the memory was first encoded [15]. In that moment, you experience a brief escape from reality in which you return to the joy experienced in the past. The hippocampal circuits that were created when the memory was first formed are reactivated alongside the ventral striatum. The ventral striatum is a brain structure responsible for releasing dopamine, a molecule that is highly involved in the body’s reward system [23, 24]. The memory-reward system is dependent on the hippocampus and ventral striatum being largely intertwined [23]. When nostalgic stimuli engage the ventral striatum, dopamine is released, strengthening the relevance and significance of these memories and making them more accessible in the future [19]. The hippocampal connections with the ventral striatum are thought to aid in the recall of these memories, forming an intricate network that contributes to nostalgia’s uniqueness [19]. Interestingly, the co-activation of the hippocampus and ventral striatum can explain why the experience of nostalgia often includes viewing past experiences through ‘rose-colored glasses’ [25]. When thinking of certain cherished memories, the negative aspects of the event can be overshadowed by the positive aspects, which contribute to the overall positive experience of nostalgia [25]. Each time you recall a nostalgic memory, dopamine reinforces the memory and the positive emotion associated with it, making it easier to recall in the future and inducing an increasingly rewarding feeling as the nostalgic memory is further re-encoded and re-stored [19]. Nostalgia stems from this recalling, where the engram, as well as the emotion and reward centers that are associated with the memory, are activated [10]. However, with these rewarding feelings and memories, a yearning for that specific time period follows [21]. Essentially, the positive feelings stemming from mental time travel are accompanied by the sadness or wistfulness due to the realization that things have since changed [26]. Interestingly, nostalgic emotions are experienced in an an ‘ebb and flow’ style, where neither the positive nor the negative feeling is gone, but rather one feeling is emphasized at a time [26]. For instance, when you’re back at the rock watching the sunset, you are reminded of your best friend who is no longer a part of your life and reminisce about memories the two of you once shared. For a moment, your happiness becomes overshadowed by longing for the past, before returning once again.
How the Past Fuels the Future: The Motivational Power of Nostalgia
The unique characteristics of nostalgia allow sentimental memories to benefit our everyday lives [27]. For instance, nostalgia can be a remarkable source of motivation [27, 28, 29]. Nostalgia has the ability to enhance our self-perceived meaning of life and solidify our intentions to pursue our most important goals [27]. Meaning in life is necessary for well-being and adaptability [30]. In fact, nostalgia therapy, which includes 45 to 60-minute weekly meetings, during which patients are instructed to think about memories that foster nostalgia, has been shown to improve the quality of life for elderly people living with depression, suggesting that nostalgia leads people to feelings of emotional safety and a higher appreciation for life [31]. Nostalgic narratives may include reflecting on important personal memories that include family and friends, and this act of remember ing helps increase feelings of social connectedness [30]. Strengthening social ties further contributes to greater fulfillment in life and helps us assign priority on what is most important to us [32]. Individuals are shown to be more successful when focusing mental resources towards a singular goal [27]. Nostalgia helps to set personal priorities, which in turn motivates attributes such as optimism, creativity, and the pursuit of one’s goals [27]. Nostalgia can also increase perseverance by placing significance upon past memories and reinforcing one’s identity and reasons for working towards their aims [33]. Lastly, ‘anticipatory nostalgia,’ where one predicts the future experience of feeling nostalgic following an event that has not yet occurred, acts as a motivating factor for new experiences [34]. Consider traveling: you might look forward to seeing beautiful sites — like the view from the mountaintop you saw online — and the nostalgic feeling of longing you will feel after you have returned back to your everyday routine [35]. Though you have not yet partaken in your journey, anticipatory nostalgia can push you to book a flight and visit that new vacation spot [35]. The multifaceted influence of nostalgia on life’s meaning, reinforcement of identity, and anticipatory emotions underscores its role as a motivational force, shaping our pursuit of significant goals and inspiring action.
Friendship’s Nostalgic Echo: Reviving Bonds and Fostering Connections
Think about how many of your friendships have changed throughout your life. Inevitably, some of your close friends faded away as life got busy, or perhaps you had an unfortunate falling-out. Nonetheless, do you remember how they listened to your problems and gave their best advice? Whether you stay in touch or not, it’s easy to reminisce on the time spent together, and doing so can function as a way to sustain the camaraderie that is lost alongside the deterioration of that friendship [1]. When friendships break apart, those involved may attempt to repair the relationship [1]. However, when rekindling the relationship is not possible, individuals can rely on nostalgic memories of the relationship to still feel socially connected to that person [34]. In fact, nostalgia can actually be triggered by a psychological threat — such as feelings of loneliness — and acts as a buffer against unpleasant emotions [31]. Through conjuring a feeling of relationships from their past, nostalgic narratives can act as a unique resource to those feeling unstable in their relationships [31]. Additionally, nostalgic memories may bring to mind past examples of relationship stability and trust, motivating conflict resolution in moments of strife with our close friends and family [38]. However, nostalgia does not only aid in relationship repair; it also motivates maintenance of sustained relationships to create more positive experiences than we have had in the past [36]. When reflecting on nostalgic experiences that are shared with other members of a group, members are more strongly bonded with each other through companionship [39].
Nostalgia can even motivate positive intentions and behaviors toward others, ranging from providing emotional support to performing charitable actions [40]. After experiencing nostalgia for past relationships, people demonstrate a larger desire to foster connections with others, such as via making new friends, repairing broken friendships, or strengthening current relationships [36]. Additionally, nostalgia amplifies the optimism one holds for forming interpersonal relationships and inspires confidence in one’s social skills [38]. By returning to a version of one’s idealized past, perceptions of one’s self-esteem and self-conception are improved [1]. Lastly, the brain often treats past experiences as predictive of what can be expected in the future. Recalling close relationships from the past through a positive nostalgic lens leads to optimistic predictions for future relationships [1]. Perhaps the next time you experience a fading friendship, instead of parting ways, take a moment to consider your shared history. As feelings come rushing back to you, nostalgia may drive your desire to reach out and rekindle past connections.
Looking Ahead by Looking Back
Nostalgia has a checkered history — it was once regarded as an emotion of great melancholy and sadness, and is now frequently perceived to be a positive emotion, one so instinctual that most of us experience it in our everyday lives [41]. When considering who has impacted your life, nostalgia can emphasize the importance of these relationships as well as your personal ambitions. Continued research in nostalgia has reframed how we perceive it as an emotion; nostalgia is often recognized as a motivating force and a way to reexamine social relationships.
Nostalgia can serve as a comforting refuge and reminder of the past, grasping memories and weaving them into the future. Through a unique lens, we can reconnect with the cherished moments and people of our past, reliving memories with a bittersweet fondness that continues to impact our present and future experiences. In fact, the next time you see a sunset that reminds you of the many you once watched with your best friend, pull out your phone to give them a call and reminisce together about the good old days.
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