Can Your Personality Change as an Adult?

In the years after the Second World War, teachers in Scotland filled in a short form about some of their fourteen-year-old pupils. They rated each child on six characteristics, among them stability of moods and conscientiousness. The forms went into an archive and stayed there.

In 2012, researchers at the University of Edinburgh tried to find those children again. Of the 1,208 who had been rated, 174 agreed to take part. Now aged 77, they rated themselves on the same six characteristics and asked someone who knew them well to rate them too.

The simple correlations between the teenage ratings and the older-age ratings showed no significant stability for any of the six characteristics across 63 years. A more complex statistical model, which accounted for differences between raters, did find significant stability for stability of moods and near-significant stability for conscientiousness. The authors concluded that lifelong stability of personality is 'generally quite low'.

Before drawing big conclusions, notice the limits. A teacher filling in a form in a classroom is not the same instrument as a 77-year-old describing themselves, and only a fraction of the original sample could be followed up. It is one study, not a verdict. But it is a useful way into the question, because the honest answer turns out to be: your personality is both fairly stable and genuinely changeable, depending on what you mean by change.

Two different kinds of change

Psychologists separate two questions that everyday language mixes up.

The first is rank-order stability: if you were more anxious than most of your friends at 25, are you still more anxious than most of them at 45? In a review of 152 longitudinal studies, Brent Roberts and DelVecchio found that this kind of consistency rises with age. The average correlation over a gap of about seven years went from .31 in childhood to .54 in the college years, .64 at age 30, and reached a plateau around .74 between ages 50 and 70. That is high, but it is not 1.0. Even in later life there is room for people to move relative to each other.

The second is mean-level change: does the average person become more or less of something over time? A 2006 meta-analysis by Roberts, Walton and Wolfgang Viechtbauer, based on 92 samples, found clear patterns. On average, people become more conscientious, more emotionally stable and more socially dominant, especially between 20 and 40. Openness and social vitality rise in adolescence and fall in old age. Agreeableness changed mainly in old age. Four of the six trait categories still showed significant change in middle and old age.

Put the two together and the picture is less contradictory than it sounds. Most people drift in similar directions as they grow older, while still keeping roughly their place in the queue. You at 50 are probably calmer and more organised than you at 20, and your old friends have probably changed in the same direction.

Can you change it on purpose?

Drift is one thing. Deliberate change is another, and it is the question most people actually care about.

The largest review so far is a 2017 meta-analysis by Roberts and colleagues of 207 studies that measured personality traits before and after an intervention, mostly psychological therapy. Over an average of 24 weeks, trait scores changed noticeably, with a typical effect of d = .37, which is a modest-to-moderate shift of a little over a third of a standard deviation. Emotional stability changed most, followed by extraversion. The type of therapy did not matter much, and the changes persisted in follow-ups after the intervention ended.

There is a fair objection here. Many of those participants started therapy in a difficult period, so part of the change may be recovery rather than a new personality. That is why studies of ordinary people who simply want to change are so interesting.

In two 16-week studies with university students, Nathan Hudson and Chris Fraley found that people who said they wanted to increase a trait tended to report increases in that trait, and in related daily behaviour, over the following weeks. The changes were modest. One of their interventions, asking people to list ways they might change, did not help at all. Another, which trained people to write specific if-then plans, did.

A later study by Hudson and colleagues gave participants weekly 'challenges', small concrete tasks matched to the trait they wanted to develop. Simply accepting a challenge predicted nothing. Only actually completing challenges predicted trait change.

The strongest evidence so far comes from a 2021 randomised trial by Stieger and colleagues with 1,523 participants who used a three-month smartphone coaching programme. People who wanted to increase a trait reported changes in that direction, and, importantly, friends, family members or partners also noticed the increases. Observers did not detect significant changes in people trying to decrease a trait. The changes held three months after the programme ended.

What this does and does not mean

It does not mean you can turn yourself into anyone you like. The changes in these studies are real but moderate, much of the evidence relies on self-report, and many participants were university students in Western countries. People who want to change may also simply start describing themselves differently.

It does mean that the idea of a fixed personality, set in stone by your twenties, is not what the data show. Traits are better understood as tendencies that can be nudged, slowly, through repeated behaviour. If something about how you feel or react is causing you persistent distress, talking to a qualified professional is a better first step than a self-improvement project.

What this means for you

The research points to a few practical lessons.

• Start from a measurement. Our Big Five test gives you a baseline, which makes any change visible rather than imagined.
• Aim at behaviour, not identity. 'Become more outgoing' is vague. 'Start one conversation with a colleague each Monday' is something you can actually do.
• Write if-then plans. In Hudson and Fraley's work, specific plans helped where general intentions did not.
• Do the thing, not just the decision. Completing small challenges predicted change; agreeing to them did not.
• Ask someone who knows you. Observers catching the change is stronger evidence than your own impression.

If you are curious about how settled your sense of self is right now, the self-concept clarity test and the personal growth test are good companions to the Big Five. Change is slow, but the evidence says it is possible.