No matter how old people are, they seem to believe that who they are today is essentially who they'll be tomorrow.
That's according to fresh research that suggests that people generally fail to appreciate how much their personality and values will change in the years ahead even though they recognize that they have changed in the past.
Daniel Gilbert, a psychology researcher at Harvard University who did this study with two colleagues, says that he's no exception to this rule.
"I have this deep sense that although I will physically age I'll have even less hair than I do and probably a few more pounds that by and large the core of me, my identity, my values, my personality, my deepest preferences, are not going to change from here on out," says Gilbert, who is 55.
He realized that this feeling was kind of odd, given that he knows he's changed in the past. He wondered if this feeling was an illusion, and if it was one that other people shared: "Is it really the case that we all think that development is a process that's brought us to this particular moment in time, but now we're pretty much done?"
Gilbert says that he and his colleagues wanted to investigate this idea, but first they had to figure out how. The most straightforward way would be to ask people to predict how much they'd change in the next decade, then wait around to see if they were right. "The problem with that is, it takes 10 years," says Gilbert.
So the researchers took a much quicker approach. They got more than 19,000 people to take some surveys. There were questions about their personality traits, their core values and preferences. Some people were asked to look back on how they changed over the past 10 years. Others were asked to predict how they thought they would change in the next decade.
Then the scientists crunched the data. "We're able to determine whether, for example, 40-year-olds looking backwards remember changing more than 30-year-olds looking forwards predict that they will change," Gilbert explains.
They found that people underestimated how much they will change in the future. People just didn't recognize how much their seemingly essential selves would shift and grow.
And this was true whether they were in their teen years or middle-aged.
"Life is a process of growing and changing, and what our results suggest is that growth and change really never stops," says Gilbert, "despite the fact that at every age from 18 to 68, we think it's pretty much come to a close."
Personality changes do take place faster when people are younger, says Gilbert, so "a person who says I've changed more in the past decade than I expect to change in the future is not wrong."
But that doesn't mean they fully understand what's still to come. "Their estimates of how much they'll change in the future are underestimates," says Gilbert. "They are going to change more than they realize. Change does slow; it just doesn't slow as much as we think it will."
The studies, reported in the journal Science, impressed Nicholas Epley, a psychology researcher at the University of Chicago. "I think the finding that comes out of it is a really fundamentally interesting one, and in some ways, a really ironic one as well," says Epley.
He says everyone seemed to remember change in the past just fine. "What was bad, though, was what they predicted for the future," says Epley.
He notes that if you want to know what your next 10 years will be like, it's probably good to look at what your past 10 years were like even though we seem not to want to do that.
Gilbert says he doesn't yet know why people have what he and his colleagues call the "end of history illusion."
One possibility is that it's just really, really hard to imagine a different, future version of yourself. Or maybe people just like themselves the way they are now, and don't like the idea of some unknown change to come.