A Swiss physician named Johannes Hofer coined the term nostalgia in the late 17th century to describe what he considered to be a cerebral disease unique to Swiss mercenaries fighting wars far from home. Fast forward over three hundred years to the present day and nostalgia is everywhere. Old movie franchises are resurrected and rebooted, songs and albums that represent "the classics" for any given generation are remastered and rereleased, and old video games are given a high definition facelift and resold. Communities and civic organizations all over the nation host retro-themed recreational events (e.g., classic car shows, blast from the past dances), and many social media websites thrive, in part, because people long to return to their past by catching up with old friends. These are just a few examples of the human love affair with days gone by. But why is the past so seductive? And how do we reconcile the historical view of nostalgia as an illness with the fact that this desire to mentally time travel to the past is so ubiquitous? Is the nostalgia disease now pervasive, causing all sorts of physical and mental health problems? Or was Hofer (and many scholars and practitioners since) wrong to conceptualize nostalgia as an illness? For nearly the last decade my colleagues and I have been striving to answer these and other unanswered questions about nostalgia. We were specifically interested in resolving the questions of what characterizes the experience of nostalgia, what effects (positive or negative) it has on people, and what causes people to become nostalgic. We have now conducted dozens of laboratory experiments and surveys and can, with some confidence, offer a new perspective on this old emotion. What characterizes the experience of nostalgia? Look in the dictionary and you will find a rather general definition of nostalgia as "a sentimental longing or yearning for the past" But what does it mean to be nostalgic? My colleagues and I explored this question by asking participants to write at length about an experience of nostalgia. Trained coders then analyzed these nostalgic narratives. Results from these coded narratives indicated that nostalgic memories tend to be focused on momentous or personally meaningful life events that prominently features close others (e.g., friends, family, romantic partners). Family vacations, road trips with friends, weddings, graduations, birthday parties, and holiday gatherings with loved ones are examples of the kinds of cherished experiences that people revisit when engaging in nostalgia. In addition, when coded for emotion-related words, results indicated that positive emotion-related words were used far more frequently than negative emotion-related words. Nostalgic memories are happy memories. What effect does nostalgia have on people? It is hard to imagine nostalgia as a disease when considering its content. Hofer proposed that nostalgia caused symptoms such as anxiety, insomnia, irregular heartbeat, and disordered eating. And Hofer was not alone is his view that nostalgia was an ailment that led to a number of problematic symptoms. Indeed, until the later part of the 20th century nostalgia was viewed either as a medical disease of a mental illness. However, past work on nostalgia was largely non-scientific. That is, no controlled studies were conducted to determine the effects of nostalgia. My colleagues and I thought it was time for nostalgia to be properly placed under the empirical microscope and thus began conducting laboratory experiments in which we systematically contrasted the experience of nostalgia with other modes of thought to determine its true consequences. Once we started conducting experimental studies, nostalgia started to look like an emotion redeemed. In a nutshell, we found that nostalgia does not have any negative effects on people, but does generate a number of psychological benefits. To illustrate, here is a quick rundown of a typical nostalgia experiment. Participants arrive at the laboratory and are informed that they are going to complete a survey regarding attitudes and emotions. They then complete a number of questionnaires as part of the study. Critically, some participants are randomly assigned to the nostalgia condition and some are randomly assigned to a control condition. Those in the nostalgia condition are provided with the dictionary definition of nostalgia, asked to spend a few minutes thinking about an experience of nostalgia, and instructed to briefly write about this experience. Those in the control condition are asked to think and write about a different (non-nostalgic) experience. The specific experience used in the control condition varies from study to study. In some studies, for example, control participants are asked to write about an ordinary experience from the last week. In addition, different studies have employed entirely different methods for inducing nostalgia. For example, in some studies, music has been used to heighten nostalgia. After the nostalgia or control condition, all participants complete a range of questionnaires to assess the effects of nostalgia. These questionnaires typically assess states related to psychological health and well-being. Here is what these studies have found. Nostalgia, compared to control conditions, does not increase negative emotions, but it does increase positive emotions. As I mentioned before, nostalgic experiences tend to be characterized as positive and this feature of nostalgia appears to translate into actual mood. When nostalgia is induced in the lab, it puts people in a good mood. In other words, thinking about cherished experiences from the past makes people feel good in the present. Nostalgia, compared to control conditions, increases self-esteem as well as perceptions of meaning in life. By allowing people to revisit cherished life experiences, nostalgia boosts positive self-regard and promotes the feeling that life is full of meaning and purpose. Nostalgia, compared to control conditions, increases perceptions of social connectedness. Again, as previously mentioned, nostalgic experiences tend to be highly social in nature. The consequence of this is that nostalgia makes people feel closer to others. Nostalgia reminds people that they are loved and valued by close others. These are just a few examples of the psychological benefits of nostalgia that have been unearthed in recent studies. Other recent studies further indicate that nostalgia reduces stress and makes people feel energized, inspired, and optimistic about the future. The punch line of all this work is that nostalgia is good for people. Contrary to past assertions, nostalgia does not harm people; it benefits psychological health and well-being. So what causes people to become nostalgic? Hofer thought that nostalgia was caused by continuous vibrations of animal spirits through fibers in the middle brain. Others proposed that nostalgia resulted from damage to the eardrum and brain caused by the nonstop clanging of cowbells in the Alps. Though we found these explanations rather imaginative, not surprisingly, my colleagues and I thought a fresh look at the causes of nostalgia was in order. As a starting point, we asked participants to indicate what situations or experiences tend to make them feel nostalgic. Social interactions (e.g., getting together with an old friend), sensory imputs (e.g., smells, music), and tangible objects (e.g., old photographs) commonly inspire nostalgic feelings. However, negative mood was the most commonly reported cause of nostalgia and, within this general category, loneliness was the most frequently listed discrete negative emotion. These findings suggest that nostalgia is triggered by feelings that could be described as psychological threat. But further work was needed. My colleagues and I again turned to experimental methods to further examine the causes of nostalgia. In particular, we believed that negative mood, loneliness, and feelings of meaningless would be potent triggers of nostalgia. We reasoned this because of the psychological functions that nostalgia serves. That is, as previously discussed, nostalgia increases positive mood, perceptions of meaning, and a sense of connectedness to others. Thus, people may naturally turn to nostalgia if positive mood is threatened, a sense of meaning in life is undermined, or feelings of social connectedness are compromised. Experiments we conducted supported these proposals. In one study, participants were randomly assigned to read one of three news articles that were chosen to induce positive mood, negative mood, or no emotion. All participants then completed a questionnaire that assessed how nostalgic they felt at that moment. Participants who read the negative mood inducing article reported feeling more nostalgic than participants who read either the positive or neutral mood inducing articles. In another study, some participants were assigned to a condition that made them feel lonely. Specifically, they completed a personality questionnaire and were then provided with false feedback suggesting that they were high on a validated measure of loneliness. Participants in the control condition were given feedback suggesting they were not high on loneliness. Again, all participants then completed a measure of nostalgia. Participants in the loneliness condition reported being significantly more nostalgic than participants in the control condition. In yet another study, some participants read a philosophical essay regarding the cosmic insignificance of human life (a threat to perceived meaning) while other participants read a philosophical essay that had no direct connection to perceptions of meaning. Again, nostalgia was then measured. Participants in the meaning threat condition reported feeling significantly more nostalgic than participants in the control condition. In short, situations that trigger negative emotions, feelings of loneliness, and perceptions of meaninglessness cause people to become nostalgic. The Past has a Bright Future Above, I described just a few examples of the many studies recently conducted in the field of social psychology on the content, function, and triggers of nostalgia. Though it has taken a few hundred years, thanks to a revived interest in this old emotion and a more scientific approach to studying it, nostalgia is getting a conceptual makeover. Nostalgia is not a disease or mental illness. Instead, it is a psychological resource that people employ to counter negative emotions and feelings of vulnerability. Nostalgia allows people to use experiences from the past to help cope with challenges in the present. And current research is further probing the many ways that nostalgia promotes psychological health. It appears that nostalgia has a bright future. Image: photo of the author looking at the historic Fargo Theater by Jenny Routledge