Nostalgia: An impactful social emotion

Nostalgia (a sentimental longing for one ’ s past) is a highly social emotion. We provide an evidence-based argument that nostalgia ’ s sociality is one of its most defining and impactful characteristics. First, we review evidence that has established the highly social content of nostalgic reflection. Second, we summarize research that has demonstrated nostalgia ’ s capacity to provide a sense of connectedness with others, and that this social connectedness, in turn, conveys intrapersonal psychological benefits (i

Nostalgia is also a highly social emotion.We argue that nostalgia's social character is one of its most defining and impactful facets.First, the content of nostalgic reflection is heavily social.Second, nostalgia supplies social connectedness, which, in turn, has positive downstream intrapersonal consequences.Third, nostalgia bears interpersonal consequences.

Social content
The content of nostalgia is highly social.Analysis of nostalgic narratives have revealed that when one is nostalgic, they nearly always reflect on people (e.g., friends, family) and social gatherings in which they are surrounded by others (e.g., parties, weddings, family reunions) [12].Compared to non-nostalgic narratives, nostalgic narratives contain more references to family (e.g., husband, daughter), social interactions, companionship, first-person plural pronouns (e.g., we, us), and references to friends [20,21].The social tone of nostalgic contemplation occurs irrespective of age [4,21] and even among narcissists [22].Finally, when people anticipate being nostalgic for a present experience (i.e., anticipated nostalgia), the present experience most commonly involves others [23].

Social connectedness
Social connectedness is a basic psychological need, critical for well-being [24].Given nostalgia's highly social content, it stands to reason that it helps fulfil this need.Supporting this idea, individuals high in trait nostalgia are more likely to use autobiographical memories to maintain intimacy [25].Also, if it is true that nostalgia provides social connectedness, then people may become nostalgic when feeling socially disconnected as a means to restore connectedness.Consistent with this notion, a recent largescale investigation during the COVID-19 pandemic [26], a time when lockdowns increased loneliness [27], demonstrated that loneliness predicted increased nostalgia.Studies in which researchers have experimentally induced loneliness [28,12] and belongingness deficits [29] have confirmed that social disconnectedness leads to nostalgia.Congruent with the notion that social disconnectedness leads to nostalgia because nostalgia has the capacity to restore connectedness, nostalgia induced by loneliness predicts increased perceptions of social support [28].
To examine the proposition that nostalgia fosters social connectedness more directly, researchers have experimentally induced nostalgia prior to measuring social connectedness.In the first test of this, Wildschut et al. [12] induced nostalgia with the event reflection task (ERT).The ERTentails randomly assigning participants to reflect on a nostalgic event or an ordinary event from their past.Wildschut et al. discovered that those who reflected on a nostalgic event evinced greater social connectedness.This is a robust finding that has been replicated over a dozen times [30].The effect has been observed among young and older adults, and in North America, Europe, and Asia.Researchers have also examined this effect using alternative nostalgia inductions.For instance, several experiments have used a music-based method to induce nostalgia [6,8,19,31].For this induction, participants are randomly assigned to read lyrics of a song that they previously identified as personally nostalgic or a song that they did not previously identify as personally nostalgic.In all the experiments using this induction, reading nostalgic (vs.non-nostalgic) lyrics increased social connectedness.Another experiment induced nostalgia with a prototype-based induction [32].For this induction, participants reflected on an event that was either characterized by nostalgia's central features [e.g., reminiscence, fondness] or peripheral features [e.g., daydreaming, desire].Those who reflected on an event characterized by nostalgia's central features reported higher social connectedness.

Downstream intrapersonal consequences
The effect of nostalgia on social connectedness is an influential effect as nostalgia-induced social connectedness conveys several positive intrapersonal downstream consequences.To begin, social connectedness gives people a sense that life is meaningful [33].It was on this basis that Routledge et al. [8] posited that nostalgia fosters meaning in life.In an experiment using the music-based nostalgia induction, they found that the aforementioned effect of nostalgia on meaning in life is mediated by social connectedness.
Sedikides et al. [19] proposed that the social connectedness afforded by nostalgia should also give people the sense of connectedness between one's past and present, i.e., self-continuity.Results from several experiments using both the ERT and music-based inductions revealed that nostalgia increases self-continuity and that this effect is mediated by social connectedness.
Researchers have also examined whether nostalgiainduced social connectedness can supply positive perceptions of the future.Social connectedness is a source of self-esteem [34,35], and self-esteem, in turn, is an antecedent of inspiration [36] and predicts greater optimism [37].Investigations have revealed that nostalgia increases both inspiration [31] and optimism [6] and that social connectedness and self-esteem sequentially mediate these effects.

Interpersonal consequences
The social character of nostalgia also conveys interpersonal consequences.

Intrapersonal emotion transfer
Researchers have investigated whether nostalgia, and its capacity to supply social connectedness, can be interpersonally transferred [21].In an experiment, older adults wrote narratives about a nostalgic event and an ordinary event from their past.Subsequently, younger adults read one of the narratives, either nostalgic or ordinary, that one of the older adults had written.The younger adults who read a nostalgic (vs.ordinary) narrative subsequently reported feeling more nostalgic themselves.In other words, the nostalgic sentiment of the older adults was transferred to the younger adults.Moreover, the younger adults who read a nostalgic (vs.ordinary) narrative subsequently evinced greater social connectedness.

Romantic nostalgia
Another interpersonal consequence of nostalgia pertains to romantic relationships.In a recent investigation, Evans et al. [38] focused specifically on nostalgia for one's current romantic relationship (i.e., romantic nostalgia).In two experiments, they induced romantic nostalgia.In one experiment, they used a modified version of the ERT in which participants reflected on either a nostalgic event or an ordinary event with their romantic partner.In the other experiment, participants listened to a song that reminded them of their romantic relationship and made them feel nostalgic (romantic nostalgia condition) or a song that they simply enjoyed listening to (control condition).In both experiments, romantic nostalgia increased commitment to and feelings of closeness with one's romantic partner, as well as relationship satisfaction, compassionate love, and passionate love.

Social approach
More generally, nostalgia promotes an approachorientation towards other people (social approach).Research has demonstrated this in several ways.One investigation revealed that nostalgia for one's university experience predicted stronger intentions to socialize with fellow alumni and to attend a reunion [39].Another study showed that nostalgia decreases the physical distance that people place between themselves and others [40].Specifically, the researchers induced nostalgia with the ERT, and then told participants that they would have a conversation with another participant who was ostensibly in an adjacent room.The researchers instructed the participants to set up two chairs to prepare the room for this conversation.Participants who reflected on a nostalgic event set the two chairs closer together than those who reflected on an ordinary event.
Another manifestation of social approach is the pursuit of interpersonal goals [41], e.g., make new friends, repair broken friendships.Abeyta et al. [20] tested nostalgia's effect on interpersonal goals.In a series of experiments, they induced nostalgia using the ERT and music.They discovered that nostalgia increases the importance people place on interpersonal goals, intentions to pursue interpersonal goals, and dedication to overcoming conflicts with friends.In addition to promoting interpersonal goals, nostalgia gives people the confidence to pursue them.In particular, Abeyta et al. further found that nostalgia amplified optimism that one would achieve their interpersonal aspirations as well as confidence in one's social skills.Wildschut et al. [12] more specifically found that nostalgia increases perceived confidence in initiating interactions, self-disclosing personal information, and providing social support.Given nostalgia's capacity to foster social approach and connectedness with others, it stands to reason that nostalgia may help people overcome the reluctance to engage in difficult social interactions.One such interaction is asking for help.People are generally reluctant to seek help [42], yet Juhl et al. [43] proposed that because nostalgia makes people feel closer to others, it may afford the courage to ask others for help.Across several experiments, these researchers induced nostalgia with the ERT, and measured self-reported help seeking (e.g., "I can ask for assistance when I am in trouble") and help seeking behavior (the time it took for participants to ask for help on a puzzle).Nostalgia increased self-reported help seeking as well as help seeking behavior (i.e., requesting help quicker) and these effects were mediated by social connectedness.
Another way that nostalgia orients people towards others is by fostering the tendency to feel others' emotions, i.e., affective empathy.Across five studies, Juhl et al. [44] demonstrated that individuals high in trait nostalgia experience greater affective empathy.This relation occurred among younger adults, older adults, and children.Affective empathy is considered a precursor of prosocial behavior [45].Juhl et al. [44] found that nostalgic individuals, by virtue of their intensified affective empathy, are more prosocial.Specifically, nostalgic individuals were more likely to donate part of their earnings as a participant to charity.This effect was mediated by affective empathy.
Experiments have confirmed the causal effects of nostalgia on empathy and prosocial behavior.Stephan et al. [40] experimentally induced nostalgia with the ERT.They then measured helping behavior by staging an interaction in which the experimenter dropped a box of pencils on the floor in front of the participants.Following prior research [46], they recorded the number of pencils that the participants helped pick up as an index of helping behavior.Participants who had previously reflected on a nostalgic (vs.ordinary) event picked up more pencils.Building upon this, Zhou et al. [47] demonstrated that an appeal for charitable donations was more effective if it was imbued with text that conveyed nostalgia (e.g., "Those Were the Days" and "It was a time like no other").Zhou et al. also examined whether nostalgia fosters prosociality via its capacity to arouse empathy.Across three experiments, they induced nostalgia via the ERT and presented information about various charities.They measured empathy toward the charities as well as intentions to volunteer for and donate money to the charities.Nostalgia increased both empathy and intentions to volunteer and donate.Empathy mediated the effect on intentions to volunteer and donate.
The social approach engendered by nostalgia clearly has positive implications, e.g., increased help seeking and giving.Yet, not all means by which we connect with others has positive implications [48].Li et al. [49] noted that bribe-taking, a morally reprehensible behavior, is also a way to build and maintain relationships.They examined whether nostalgia cultivates bribe-taking.In their experiments, they induced nostalgia with the ERT and then measured bribe-taking intentions or bribetaking behavior.Nostalgia increased both.

Prejudice reduction
A final interpersonal consequence of nostalgia is prejudice reduction.In several experiments, Turner et al. asked participants to reflect on a nostalgic or ordinary experience with a person from a specific stigmatized group (i.e., overweight [50,51], mentally ill [52], older adults [53]).Those who reflected on a nostalgic experience subsequently expressed less negative attitudes toward the stigmatized group.

Conclusion
Nostalgia's social character is one of its most significant and influential features.The content of nostalgic reflection is remarkably social.Nostalgia makes people feel socially connected.Nostalgia-induced social connectedness breeds meaning, self-continuity, optimism, and inspiration.Nostalgia begets interpersonal consequences.It can be interpersonally transferred.It increases physical closeness, help-seeking, empathy, and prosocial behavior.It fosters a healthier outlook of one's romantic relationship and it diminishes prejudice.
The existing body of research convincingly demonstrates that nostalgia is a highly social emotion, and consequently, conveys positive personal and social effects.Recent work has also demonstrated that nostalgia's social character bears the negative social consequence of fostering bribetaking.Regarding the latter, future research is needed to identify (1) whether the social character of nostalgia leads to other negative outcomes and (2) how to steer nostalgia's sociality away from harmful, and toward helpful, outcomes.Moreover, future work is needed to investigate how the beneficial effects of nostalgia can be harnessed to improve the quality of people's social lives.For example, could a nostalgia app for phones increase nostalgia and help those who are socially isolated feel more connected?Might such ecological nostalgic prompts lead people to approach others as a means to fulfill their interpersonal goals, make new friends, and attain help?Can relationship therapists use romantic nostalgia to restore their clients' romantic flame?These questions mark the frontier of nostalgia research.

Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.