Why We’re So Preoccupied by the Past

Why We’re So Preoccupied by the Past

By Jeremy R. Manning edited by Daisy Yuhas

The arrival of a new year often brings up a mix of emotions. For some of us, a change in the calendar serves as a chance to reflect on the good and bad things that happened over the previous 12 months. For others, it’s a chance to start fresh with an eye toward the future. As a scientist, I have long been fascinated by the incredible ability people have to go beyond the present moment. Our physical selves seem forever chained to each moment as it occurs, but our mind revisits past experiences and imagines future experiences at will.

Much of what scientists know about how people remember past events and guess about future ones comes from studies that focus on a given person’s own experiences. The fundamental idea is simple: what you do, or what you plan to do, somehow gets written into the complex networks of your memory systems. Researchers can study what your brain does when you form new memories, retrieve those recollections, guess about the future, make plans, and so on.

In recent research, one of my graduate students at Dartmouth College, Xinming Xu, came up with a brilliant twist on these phenomena. He wondered how we mentally visit the past and future of other people’s lives. Suppose you’re meeting a total stranger for the first time. Guessing about that person’s past and future is central to how you interact with them. Those conjectures help us to decide whether we like or dislike someone, whether we see them as a potential romantic partner or a threat and so on. But what clues might we draw on? Our team’s investigation into that question led to some surprising insights about how we consider time and how that affects our interactions.

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Our team began by thinking through some basic properties of what a snapshot in time can tell people about the preceding and proceeding moments. In the branch of physics called classical mechanics, what is happening now tells us equally about the past and future: if someone knows the current position and velocity of a ball flying through the air, they can guess where it was a moment ago and where it will be in the future. Might these same principles apply to subjective experiences such as social interactions and mental processes? If so, we should be equally good at making inferences about a stranger’s past as we are at doing so about their future.

Our team put this idea to the test by asking 36 participants to watch snippets selected from a TV show and then make guesses about what occurred before or after each scene. We found that our participants were nearly always better at guessing about events that came before the snippet than events that came after. But how could this be?

When we dug further, we found a simple explanation—tied to a remarkable pattern. People’s guesses about TV characters’ pasts and futures seem to be guided, in large part, by the content of characters’ conversations. Because the characters in that TV show talked about the past 1.7 times more than the future, participants tended to learn more about events from earlier on in the story.

That finding could simply reflect the TV program people had watched, so we repeated our study using a different show. We were surprised to find that these new characters also tended to talk about the past more often than the future. But perhaps that was just a coincidence? We then ran a large-scale analysis of tens of millions of real and fictional conversations, selected from books, movies, TV shows, and spoken and written real-world interactions. Incredibly, we found that both fictional and real people, on average, showed that same tendency. From what we can tell, this asymmetry appears to be a fundamental aspect of how humans communicate.

Why dwell more on the past than the future in conversation? People certainly know more about their past than the unknown future, so perhaps we humans tend to stick with what we know. One consequence is that biases in what people know and think show up in communication with others, and as a result, the information people take away from the conversations they observe and participate in is inherently biased in favor of the past.

Ultimately, people are far better at inferring past events than predicting future ones. Our findings also fit into a much larger body of research that explores how and why people mentally visit the past and future. For example, a central tenet of mindfulness training is to attempt to focus on the present moment, which can help people feel grounded and appreciate where they are, who they are with and what they have. But the mind sometimes seems to pull people away, unmooring them in time. That can be a distraction—causing someone to pay less attention to, say, an ongoing conversation—or part of a harmful pattern, such as rumination, which is linked to depression.

But these acts of mentally pulling away from the present can serve a practical purpose. When something people are experiencing in the present shares some aspect of their past, it can cause them to spontaneously relive those earlier moments. For example, the smell wafting through the door of a bakery as you pass by on the street might evoke a childhood memory of your grandmother’s cooking. You might then seek out those baked goods in the hopes of recapturing some of those warm, cozy feelings. These reminders of times past influence behaviors, helping people to navigate complex situations or environments using cues that were useful in the past. The reason we have memories in the first place is because they help us to predict—however imperfectly—what is likely to happen in the future.

Even if our conversations tend to favor the past, I fall into the camp of seeing the new year as an opportunity for a fresh, exciting start. If something in the past year didn’t go quite as planned, our memories give us an opportunity to learn and grow from our mistakes and to avoid making the same errors in the future. And for the things that did go well over the past year, we can draw on our memories to make us happier in the present.

Are you a scientist who specializes in neuroscience, cognitive science or psychology? And have you read a recent peer-reviewed paper that you would like to write about for Mind Matters? Please send suggestions to Scientific American’s Mind Matters editor Daisy Yuhas at dyuhas@sciam.com.

This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.