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Personality changes with age (maturity principle)
2006 meta-analysis· Finding or experiment
Well replicatedStrong, repeated evidence.
Personality is not fixed: on average, people become more conscientious, agreeable and emotionally calm as they age.
See it on the Psychology map →What it says
A 2006 meta-analysis by Brent Roberts and colleagues pooled 92 long-term samples and found steady change, with the biggest shifts between ages 20 and 40. Conscientiousness and emotional stability rise most in young adulthood; agreeableness keeps rising into the 60s; openness and sociability climb in adolescence and dip in old age. Researchers call this the maturity principle. People also keep roughly the same rank relative to peers, though less so over many decades.
Why it matters
It counters the belief that personality is set by 30, and suggests that change is normal and possible at any age.
The evidence
Longitudinal studies following the same people for decades in many countries; a 62-nation study found that where adult roles like work and family start earlier, maturing starts earlier.
Open questions
Is the change driven by biology or by adult roles like work and parenting? People also underestimate how much they will change, the 'end of history illusion.'
Connections (2)
▸Personality changes with age (maturity principle) continue into Aging: what declines and what doesn'tWell replicated
The connection
Personality keeps changing past midlife. People tend to grow more agreeable and emotionally stable into their 60s and 70s, while openness, sociability and later conscientiousness dip in very old age. Older adults also focus more on positive experiences. A sudden, marked late-life personality shift, however, can be an early sign of brain disease.
Who showed it and when
Long-term studies in the US, Germany, Australia and elsewhere; a 2020 coordinated analysis by Eileen Graham and colleagues pooled 16 longitudinal samples.
The evidence
Multiple panel studies show the late-life pattern, though measuring very old adults is harder because frail participants drop out.
Open questions
Whether late-life declines reflect normal aging, illness or retirement's changed demands, and how best to tell normal change from early dementia.
▸Personality changes with age (maturity principle) describes lifelong shifts in The Big Five personality traitsWell replicated
The connection
The maturity principle describes how average Big Five scores move across life: conscientiousness and emotional stability rise in young adulthood, agreeableness rises later, and openness peaks young. People's rank relative to peers is fairly stable, so change is mostly a shared drift.
Who showed it and when
Brent Roberts, Kate Walton and Wolfgang Viechtbauer's 2006 meta-analysis of 92 samples; Avshalom Caspi, Roberts and Rebecca Shiner named the 'maturity principle' in 2005.
The evidence
Longitudinal studies in many countries find similar patterns. Therapy can also shift traits, especially emotional stability, within months.
Open questions
Whether biology or social roles like work and parenting drive maturing; similar age trends reported in chimpanzees hint at biology.