In a 2013 study spanning more than 19,000 adults aged 18 to 68, people expected far less personal change over the next decade than people 10 years older reported experiencing over the same years of life

More than 1,800 years ago, a man was writing notes to himself in Greek. He ran the most powerful state of his day, and Encyclopaedia Britannica notes that he wrote them while leading military campaigns along the Danube. Now and then he noted where he was. In George Long's 1862 translation of the notes, one section ends with "Among the Quadi at the Granua," and the next ends with "This in Carnuntum."

When I first read these notes, I noticed how much of them is about change. It isn't one famous passage. It's a steady return to the subject, entry after entry: the world changing, things passing, his own judgments shifting.

"Observe constantly that all things take place by change," he writes in one entry, "and accustom thyself to consider that the nature of the universe loves nothing so much as to change the things which are and to make new things like them."

The man was Marcus Aurelius, Roman emperor from 161 to 180, and those notes became what we now know as Meditations.

He didn't exempt himself. "All our assent is changeable," he writes in Book 5; "for where is the man who never changes?" By "assent" he means his judgments and beliefs.

Marcus expected to change. Most of us don't expect as much change as we should. A 2013 study suggests that we may underestimate how much our personalities, values and preferences will change.

And even if you accept that, you can't know in advance which way you'll change. That leaves a question the Meditations keep circling: if the person you'll be in ten years is partly a stranger, what do you hold on to?

Marcus had answers, and so did a few other philosophers. We'll get to them. But first, the study.

How the 2013 study measured change

The study was run by Jordi Quoidbach, Daniel Gilbert and Timothy Wilson and published in the journal Science in January 2013 as "The End of History Illusion." Its opening paragraph offers a striking illustration of the idea: "Young adults pay to remove the tattoos that teenagers paid to get, middle-aged adults rush to divorce the people whom young adults rushed to marry, and older adults visit health spas to lose what middle-aged adults visited restaurants to gain."

Across several studies, they gathered responses from more than 19,000 people aged 18 to 68. As they put it, young, middle-aged and older people "all believed they had changed a lot in the past but would change relatively little in the future." That gap is what they called the end of history illusion.

The paper's supplementary notes say that nearly all the participants were unpaid volunteers from the website of Leurs Secrets du Bonheur ("Their Secrets of Happiness"), a France 2 television show broadcast between October 2011 and January 2012. Instead of pay, they were offered feedback on their wellbeing. More than 80% were women, so the authors analyzed men and women separately. The illusion showed up in both.

So how do you measure change without waiting ten years? Well, in this case, they didn't follow anyone. People were randomly given one of two jobs. "Predictors" estimated how much they would change over the next decade. "Reporters" estimated how much they had changed over the last one. The researchers then compared, say, 40-year-olds' predictions with what 50-year-olds said about their own previous ten years. In the main studies, these were different people.

For personality, 7,519 people filled in a ten-item personality questionnaire. For values, 2,717 people rated ten basic values such as success and security. For preferences, 7,130 people were asked about their favorite music, vacation, food and hobby, and the name of their best friend. A favorite-movie question was dropped because more than 200 people didn't complete it. The authors took that as a sign that people "do not find it easy to remember their favorite movie from a decade ago."

A smaller experiment, with 170 people recruited separately online, put a price on the idea. People who named their current favorite band said they'd pay about $129 to see it play in ten years' time. People who named their favorite band from ten years ago said they'd pay about $80 to see that band play now. As the authors put it, participants "substantially overpaid for a future opportunity to indulge a current preference."

Were the reporters simply misremembering? The authors checked their personality results against MIDUS, a separate long-term US survey in which 3,808 adults took a personality test twice, about a decade apart. MIDUS used a different test, so the comparison was indirect, but the authors report that the change the reporters described was "almost identical" to the change MIDUS measured. The predictions fell well short of it.

In two of the three main studies, the gap was larger for younger people than for older ones, but it appeared at every age the authors could analyze.

As for why, they offered two possibilities. One is that people tend to believe "their personalities are attractive, their values admirable, and their preferences wise," and may not want to imagine moving on from that. The other is that imagining future change is harder than remembering past change, and "people may confuse the difficulty of imagining personal change with the unlikelihood of change itself."

The paper ends on this line: "History, it seems, is always ending today."

What the study can't tell us

The first limit is the design: it compares different people rather than tracking the same people over time.

A sharper objection came shortly after publication. Writing in the BPS Research Digest, Christian Jarrett relayed an objection first raised in a blog post: predictors "might well have believed that their personality will change, but they didn't know which direction it will change in." If you expect to change but can't say whether you'll become more outgoing or less, sticking with your current score may be your most accurate guess.

To be fair, the authors had partly anticipated this. In a follow-up with 1,163 people, they simply asked how much people had "changed as a person" or would "change as a person," and the illusion still appeared. Jarrett's view was that this "doesn't entirely deal with the direction of change issue."

Gilbert later addressed the point himself, on NPR's TED Radio Hour in 2015. Imagine reaching a dead end in a road, he said. You can picture turning left as easily as right, but not knowing which way you'll turn "doesn't mean turning is unlikely." In the same interview he summed up the finding: you'll probably change less in the future than you did in the past, but more than you expect.

Nobody, Gilbert included, claims you can know in advance which way you'll turn.

The volunteers were also a self-selected TV audience, and mostly women. That doesn't make the results wrong, but it isn't a representative sample.

The last limit matters for many readers here. Participants ranged up to age 68, but the decade-matched comparison required predictors to be no older than 58, because each was compared with reporters ten years older. The authors found the illusion across the ages they could compare, but they couldn't directly test whether people in their 60s underestimate how much they'll change over the following decade. They say more research is needed to tell whether the illusion "does or does not disappear at the very upper end of the age continuum."

So how do you live with a self that won't hold still?

If change is a given, and its direction isn't, the obvious question is how to live with it. Here's how two ancient philosophers approached the problem.

Remember that change is nothing special

Marcus put the question to himself bluntly. "Is any man afraid of change? Why what can take place without change? ... And canst thou take a bath unless the wood undergoes a change? and canst thou be nourished, unless the food undergoes a change?" Then he turns it around: "Dost thou not see then that for thyself also to change is just the same, and equally necessary for the universal nature?"

The opening line gets quoted everywhere. The last line, where he turns the argument on himself, often gets left off. Yet that's the point of the passage: firewood, food, and then him. He doesn't predict how he'll change. He simply refuses to treat his own change as a special case.

Names to come back to

In Book 10, Marcus gives himself a short list of names to live up to: "good, modest, true, rational, a man of equanimity, and magnanimous." Then he adds: "take care that thou dost not change these names; and if thou shouldst lose them, quickly return to them."

What strikes me is that Marcus doesn't assume he'll always live up to these names. He expects to lose sight of them, and tells himself to return. That's the contrast with the end of history illusion. The illusion is a forecast: I've more or less finished becoming who I'll be. Marcus's names aren't forecasts. They're commitments, made by someone who expected to change.

Change course if needed, but slowly

Cicero, the Roman statesman and philosopher, took up the question most of us dread. If you've built your life around a path, he wrote in On Duties, stick with it, "unless, perchance, he should discover that he has made a mistake in choosing his life work. If this should happen (and it can easily happen), he must change his vocation and mode of life." If circumstances don't make it easy, "it must be made gradually, step by step," the way wise people loosen a friendship that no longer works "little by little" rather than cutting it off at a stroke.

Cicero assumes that the person who made a choice may one day disagree with it, and he plans for that person rather than pretending they won't arrive.

That's the difference between the end of history illusion and what Marcus was doing in those camps along the Danube. The illusion assumes the work of becoming is more or less done. Marcus never assumed that. Running an empire at war, he was still asking "where is the man who never changes?" about himself, and still writing down the names he meant to come back to.

The study can't tell you who you'll be in ten years. Neither could Marcus. What his notes offer instead is a way of separating change from drift: expect that much of you will move, notice when your roles and circumstances have changed, and keep deciding what is worth returning to.

If the person you'll be in ten years is partly a stranger, the useful question may not be how to keep them the same. It may be what you would still want them to come back to.

Sources

• Quoidbach, J., Gilbert, D. T., and Wilson, T. D. (2013). "The End of History Illusion." Science, 339(6115), 96–98. Full paper and supplementary material (PDF).
• Inter-university Consortium for Political and Social Research (ICPSR). Leurs Secrets du Bonheur research dataset and study information.
• NPR, TED Radio Hour (2015). Transcript featuring Daniel Gilbert discussing the end of history illusion.
• British Psychological Society, Research Digest. Christian Jarrett's commentary on the end-of-history illusion and the direction-of-change objection.
• Marcus Aurelius. Meditations, translated by George Long (1862). Especially Books 5, 7 and 10. Book 5.10 and Book 7.18.
• Cicero. On Duties (De Officiis), Book 1, on changing one's vocation and mode of life.
• Encyclopaedia Britannica. "Meditations," work by Marcus Aurelius, for the historical background to its composition.