On election night, there was a spontaneous outpouring of young celebrants, black and white, into Washington D.C.'s U Street corridor. U Street, home to the famed Lincoln Theatre and Ben's Chili Bowl, was once the center of African-American culture in D.C., until it was burned and gutted by the race riots of the '60s. It has taken decades for this historic neighborhood to recover from those divisive times, so to see it throbbing with youthful hope was poignant and exhilarating.

Scenes like that were played out all over the country. But a week later, it's fair to ask ourselves, how are we going to carry that excitement and goodwill into the future? Is it possible to sustain it, or are we just setting ourselves up for disappointment with our high expectations?

Psychologists are very interested in how the mind processes events like this historic election, and how it turns them into hope and expectation—or regret and disappointment. How powerfully do our experiences today shape our emotions of tomorrow? In short, what predicts future happiness?

Researchers call this emotional forecasting. Humans are arguably the only animals capable of imagining what doesn't already exist, conjuring up future scenarios. That's a trait of our highly evolved brains, but evolution apparently stopped short—because we're not all that talented at predicting our own state of mind. Indeed, study after study has shown that we're usually way off the mark with our predictions. We believe that winning the lottery will make us blissful, and it rarely does. We think being jilted will devastate us, yet we almost always bounce back.

Why are we so bad at this? A growing cadre of psychologists—Dan Gilbert of Harvard, Timothy Wilson of Virginia, and others—have been exploring the cognitive machinery of emotional forecasting—and its failures. Their studies point to a few possible reasons for our failures of imagination.

One major stumbling block is our brain's natural tendency to compare events. For example, these psychologists ran a simple experiment in which they had volunteers contemplate a plate of potato chips. For some, there was a plate of sardines sitting nearby, while for others there was a fine Swiss chocolate. Those who were sitting near the sardines predicted that the chips would taste much better than did those eyeing the chocolate; they were mentally comparing the chips to fish or chocolate. But in fact, when they actually ate the chips, there was no difference in their enjoyment. They "mis-wanted" the chips because of a faulty comparison. Right now, a lot of Obama loyalists may be thinking about the past eight years as a plate of sardines, and falsely interpreting that as a guarantee of something delicious to come.

People are also thrown off by what psychologists call the "durability bias." That's just a jargony way of saying that, when we have an emotional experience, we automatically assume that the emotion—excitement, say—will continue at the same level of intensity for the foreseeable future. It's irrational, but apparently the brain is not wired to imagine the gradual dissipation of emotion over time: slightly less excitement tomorrow, even less the next day and so forth.

The fact is most people's emotions, good and bad, gradually head back toward a preset emotional baseline, but it's very difficult to see that when you're in a peak experience. Watching the crowds on U Street, the farthest thing from my mind was the notion that all this wonder would evaporate. We're not wired for cynicism.

So we're clever enough to know the future is coming, but not nearly clever enough to accurately project ourselves into it. And that leads to unrealistic expectations. This distortion is compounded by another deep-wired cognitive tendency—the tendency to view events in a vacuum, without any context. Think about election night again. In order to realistically project ourselves into the future, to view the Democratic victory in some kind of perspective, we would have to say something like this to ourselves: this is an amazing event, unprecedented in history, but tomorrow I have to revise my résumé because work isn't going so well, plus my kid may be coming down with the flu, and my old Saab's transmission is likely to give out, and on and on. In other words, there is a lot going on in our lives, but the brain can only do so much, and right now the election is pretty much eclipsing all the other stuff. But all that other stuff will creep back into focus over the days and weeks and months ahead. And so we get the inevitable letdown.

But is it inevitable? Is there anything we can do to avoid these cognitive pitfalls? Well, perhaps. Gilbert and Wilson and colleagues did a series of experiments a while back that offer some hope. They studied college students at the University of Virginia and Virginia Tech, just before and after a big football game between these longtime rivals. They asked them to predict how happy (or sad) a victory (or loss) would make them in the future, and then they actually measured the volunteers' sense of well being later on. But here's the twist. They had some of the students keep a prospective "diary" before the game. That is, they projected themselves into the future and wrote down everything that they imagined they would be doing day to day: studying, partying with friends, writing papers, and so forth. They found that those who did this—who basically put the prospect of a depressing loss (or joyful victory) into the perspective of daily life—had much more realistic expectations for their future happiness.

Now, we don't have to actually write such diaries. But apparently, with some mental work, we are capable of keeping peak experiences in proper perspective. This does not mean we shouldn't savor the vivid emotional memories of election night. I know I'm not ready to let go of that U Street image of kids ushering in this new era. But it is just that, a peak experience, the beginning of a long slog ahead.

Wray Herbert writes the We're Only Human blog at www.psychologicalscience.org/onlyhuman