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Is the person you are today the real, final you? Harvard study says you’ll change more than you think

It’s a classic exercise at the start of a new year: We reflect back on just how much we have changed. We are more mature, more patient, less impulsive, we may tell ourselves.

But when it comes to projecting forward, to imagining our future selves, most of us find it hard to believe we will change much. We’ll always have the same personality traits, values, best friends, and favorite things.

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Not so, according to a study by psychologists at Harvard and the University of Virginia.

People, young and old, routinely underestimate the amount they will change over the next 10 years. They seem to suffer from the delusion that the person they’ve become is the real and final version. Researchers call it the “end of history illusion.”

“I have to tell you that never in my wildest dreams when I had a long ponytail and was hitchhiking around the country and playing my guitar did it occur to me that my greatest joy would be sitting next to the love of my life, eating dinner on a TV tray, and watching ‘Jeopardy!’ ” said Daniel Gilbert, a psychology professor at Harvard University and a co-author of the study, published Thursday in the journal Science.

“But now I’m the guy who does that, and I know with great confidence,” he added in jest, “I will never change.”

The researchers found that people were far better at reporting how they had changed over the past decade than at predicting how they would change in the future.

‘What we never do is imagine . . . that we will be smiling knowingly at our naivete.’

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To test how well we predict and remember personal change, the scientists surveyed 19,000 people ranging from age 18 to 68. Their answers demonstrate that people not only underestimate how much they will change, but may use such information to make bad decisions, for example investing too much in a present-day preference because they assume it will remain true in the future.

As part of the study, people were asked to complete a standard personality assessment and either report how they would have answered it 10 years ago, or predict how they would answer it 10 years from now. Then, instead of waiting 10 years to see how predictions were borne out, the authors compared people of different ages. For example, 18-year-olds’ predictions about how much they would change in the future were compared with 28-year-olds’ reports of how much they have changed.

At every age, people predicted less change than had actually been reported by people 10 years older, suggesting they were underestimating how much change was likely in store for them.

To test their results, the researchers used a personality survey of nearly 4,000 adults taken a decade apart. The rate of actual personality change in that sample was very similar to how much change participants reported when looking back in time. But it was significantly more change than people predicted when looking forward.

One implication of the research is that making long-term decisions, such as buying a house or marrying or taking a job based on what we value and are like now, may lead us astray. When people were asked about a much less significant decision — how much they would pay to attend a concert of their favorite band in 10 years — the ­researchers found that people were willing to pay $50 more than people would pay to see their favorite band of a decade ago perform in the next week.

So how should we make choices with lasting repercussions? Gilbert thinks the answer may lie in a study he published three years ago in Science, which found that people made better decisions when they were informed by others’ experiences.

Women were asked to predict how much they would enjoy a speed date with a man. They based their prediction either on a report of how much another woman enjoyed a speed date with that man, or a comprehensive profile, including a photo and the guy’s favorite movie, sport, book, song, food, and class.

More women believed that they would make a better choice when given all the details about the man, but in fact most did better when they made predictions based on another’s experience.

If you want to make a decision about your future self, Gilbert suggests, look around at people 10 years older and follow their lead.

Margie Lachman, a psychology professor at Brandeis University who studies adult development, said the study was well done, but a portion of the results surprised her.

In her own research, she has found that people tend to overestimate both how much they have changed and will change. That is in part due to the human urge to see that we’ve improved and hope for more in the future.

“If you look back, adults are thinking they’ve grown and improved and progressed over the 10 years,” Lachman said. “People would be disappointed to think one hasn’t experienced growth.”

Similarly, she said, young and middle-aged adults tend to overestimate how much they will change in the future; they think they will be more satisfied with life over the next decade when there is little actual change.

Gilbert said that there’s a simple reason his study may depart from previous work in the area. The tests his group used looked at fundamental personality traits such as introversion or anxiety, and specifically avoided questions such as whether people think they will make more money, be more fit, or be more successful.

The researchers looked at characteristics that people, including Gilbert himself, think are more fixed. “I’m a middle-aged man and when I sit around talking with other middle-aged people, we talk about how we are different than when we were young,” Gilbert said. “What we never do is imagine in the future that we will be smiling knowingly at our naivete.”

Carolyn Y. Johnson can be reached at cjohnson @globe.com. Follow her on Twitter @carolynyjohnson.
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