Will you change more than you think?

In a recent Q&A, Tim Ferriss was asked which of his ideas he wishes people would stop following. He didn’t name one. He said: “I wrote The 4-Hour Workweek when I was 29. I am now 49.” And: “I would just be aware of where someone is in their journey when you read books.”

It’s good advice. The research says it applies to a book you haven’t written yet as well: your own plans.

Everyone thinks they’ve arrived

In 2013, Jordi Quoidbach, Dan Gilbert and Tim Wilson ran six studies with more than 19,000 adults aged 18 to 68. The design was simple. Ask 40-year-olds how much they expect to change over the next ten years. Ask 50-year-olds how much they changed over the last ten. Same decade of life, two views of it.

The forward-looking group always guessed low. That held for:

• Personality: how outgoing, organised or anxious you are
• Values: how much you care about success, pleasure or security
• Preferences: favourite music, holidays, food, hobby, best friend

It held at every age band. For values and preferences the gap shrank with age but was still there past 50. For personality it didn’t clearly shrink at all. The authors called it the end of history illusion: “History, it seems, is always ending today.”

People pay extra for a future self who still loves the same band.

In one small study, people said they’d pay 61% more to see their current favourite band in ten years’ time than people said they’d pay to see their favourite band from ten years ago play this week.

Isn’t that just people exaggerating their growth?

The authors checked. A long-running US survey, MIDUS, re-tested about 3,800 adults roughly nine years apart. The change it measured was almost the same as what people looking back reported. The predictions were the outlier.

Two cautions. MIDUS used a different questionnaire, so it’s a comparison, not a direct match. And as Christian Jarrett pointed out at the time, if you expect to change but don’t know which way, “no change” is the safe answer on a scale. That would look like the illusion. The authors had partly tested this: asked simply how much they’d change as a person, with no direction, about 1,100 people still guessed low.

The 63-year study, and why it’s weaker than it sounds

Harris, Brett, Johnson and Deary (2016) found Scots born in 1936 whose teachers had rated them at about 14, in 1950, on six traits: self-confidence, perseverance, stability of moods, conscientiousness, originality and desire to excel. In 2012–13, 174 of them, now about 77, rated themselves on the same traits, and someone who knew them well rated them too.

Most links between 14 and 77 were near zero. The strongest, stability of moods, was about .12. The authors’ conclusion: over 63 years, “there is hardly any relationship at all.”

That’s the line that gets shared. The authors’ own caveats get shared much less:

• Each trait was a single question.
• A teacher rated at 14; the person or a friend rated at 77.
• Teacher ratings tracked childhood IQ.
• The 174 who took part were brighter and more dependable than the original group, which makes stability harder to detect.

What 189 studies say

Bleidorn and colleagues (2022) combined 189 long-term studies covering about 178,500 people. Stability — how well one measurement of your personality predicts the next — rises steeply through childhood and the teens, reaches about .75 by the mid-20s, and barely moves after that. Averaged over everything it’s about .6: strong, not fixed.

It falls as the gap between measurements grows. But over gaps of decades it stays above about .2 for people first measured as teenagers or older. Sixty years tells you a little — not nothing. Harris’s near-zero is lower than the wider evidence would predict.

The line moves; your place in it mostly doesn’t

These two findings answer different questions. Stability is about your place relative to other people. The end of history illusion is about how far you move.

You can do both at once. In 92 samples, Roberts, Walton and Viechtbauer (2006) found that, on average, people become more conscientious, more emotionally stable and more assertive across adult life, mostly between 20 and 40. When most people move the same way, you can change a lot and keep your place.

Not settled everywhere

For life satisfaction, it’s contested. Harris and Busseri (2019) used three waves of MIDUS (2,390 people). About 38% predicted the right amount of change, 26% too much, and 36% too little — mostly by expecting none. They concluded there was no general illusion. Quoidbach, Gilbert and Wilson (2020) re-analysed the same data and reached the opposite view: the average stays put while individuals move, like lifts in a tall building.

Nor is it known why the illusion happens. The original authors offer two guesses — we like who we are now, and imagining change is harder than remembering it — and say their data can’t decide between them.

What to do with it

• Read old advice by the author’s chapter. Including your own five-year plan.
• Don’t cringe at your old plans, and don’t obey them. They were written by someone with roughly your temperament and different wants.
• To predict your own change, ask someone ten years older how much they changed. That’s the comparison the research uses.
• When you pay now for a future self, leave a door open. Assume they’ll want something a bit different. (This is advice, not a finding — the only money study is small and hypothetical.)

Dan Gilbert’s line from his 2014 TED talk: “Human beings are works in progress that mistakenly think they’re finished.”

“The line moves, your place in it mostly doesn’t” is our way of putting it, not a finding.

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Sources and reporting notes: US online samples (Quoidbach’s mostly women), the US MIDUS survey, one Scottish cohort, and a meta-analysis of mostly Western studies. No New Zealand data found. The band study’s US dollar figures are given as a percentage only. Roberts et al. (2006) and the 2020 comment read via abstract; the TED quote taken from the talk’s page.