New research finds that people rate personality as one of the most stable things in their lives. Eight longitudinal studies following 166,971 people across 75 years of adulthood show it is one of the least stable.
The belief that adult personality is fundamentally stable is remarkably persistent. It shows up in everyday conversation (“that’s just how she is”), in the self-help industry’s emphasis on accepting unchangeable traits, in the advice people give each other about choosing romantic partners, and in legal and philosophical frameworks that assume continuity of character over time. The scientific basis for this belief collapsed decades ago, but the belief itself has proven far more durable than the evidence that supposedly supports it.
A new study published in Communications Psychology, part of the Nature portfolio, has measured the gap between what people believe about personality change and what actually happens, using a combination of representative survey data and one of the largest longitudinal personality datasets ever assembled. The gap is larger than most psychologists expected.
Researchers led by Adam Wright at the University of Zurich, working with collaborators including Christopher Hopwood and Wiebke Bleidorn, first conducted a nationally representative survey of 887 American adults. Participants were asked to estimate how much the Big Five personality traits changed at different life stages, rating each transition from age 15 to 25, 25 to 35, 35 to 50, 50 to 65, and 65 to 90. They were also asked to rate how much other aspects of life change across the same periods: life satisfaction, physical health, income, relationship quality, career standing, leisure activities, and more than a dozen other domains.
Personality ranked among the most stable attributes in participants’ estimates. People believed it changed less than income, less than health, less than relationships, less than virtually every other life domain they were asked about. The mental model most Americans hold of personality is one of fundamental, near-permanent stability.
The researchers then compared those beliefs to what actually happened in eight large-scale longitudinal studies from the United States, Germany, Australia, and the Netherlands. The combined dataset covered 166,971 people who had been followed for years or decades with repeated personality measurements, allowing the team to model actual change trajectories across the full span of adult life from age 15 to 90.
The findings did not support what people believed.
What 166,971 people’s personality data actually shows
The team measured personality change in two distinct ways, each revealing something different about the nature of the change.
Net change captured the overall direction of personality trait movement from one age to another. Did extraversion rise or fall between 25 and 50? Did conscientiousness increase between 40 and 65? This measure captures the population-level trajectory of each trait across a given period, averaged across the people who went through it.
Cumulative change captured something more granular: every rise and fall in a personality trait across an individual’s development, even if the person ultimately ended up near where they started. Someone who became dramatically more neurotic during a difficult decade before recovering might show little net change but very large cumulative change. Cumulative change is the measure of how much the trait actually moved through life, regardless of where it landed.
Across both measures, the actual changes in personality were dramatically larger than participants had predicted.
In year-to-year comparisons, people underestimated personality change in 90% of cases. In lifespan comparisons spanning the full arc from age 15 to 90, people underestimated personality change every single time, across all five Big Five traits, without exception.
The magnitude of the actual changes was also striking. When the researchers standardized the data to allow direct comparison between personality changes and changes in other life domains, Big Five trait changes were comparable to or larger than changes in life satisfaction, physical health, income, and relationship quality over the same periods. People had believed personality was one of the least changeable things in their lives. The data showed it was among the most changeable.
“Laypeople rated the Big Five traits as having less change across the lifespan than nearly all other characteristics,” the researchers wrote. “Analyses using eight large-scale longitudinal datasets revealed that standardized yearly and lifespan mean-level changes in the Big Five were comparable to, and often greater than, changes in variables like life satisfaction, health, and income.”
How personality actually changes across the lifespan
The longitudinal data produced a specific picture of how each Big Five trait tends to evolve with age, which the researchers describe as systematic rather than random.
Neuroticism, the trait most associated with emotional reactivity, anxiety, and negative affect, tends to decline through most of adulthood. People typically become emotionally more stable as they age, experiencing fewer intense negative emotional responses to stress and frustration. The decline is gradual and continues well into late adulthood rather than plateauing in middle age.
Conscientiousness, which captures organization, reliability, and goal-directedness, tends to increase from early adulthood through the fifties and sixties. The responsible behaviors associated with work, family, and financial management appear to shape the trait toward greater expression over time.
Agreeableness, the trait associated with warmth, cooperation, and interpersonal sensitivity, also tends to increase with age, though the trajectory is more variable and shows larger individual differences than conscientiousness.
Openness to experience, which captures curiosity, imagination, and receptivity to new ideas, shows a more complex trajectory. It tends to remain stable or increase through middle adulthood before declining in later life, though this pattern varies substantially by educational background and life circumstances.
Extraversion shows the most variable trajectory across datasets and individuals, with general tendencies toward modest decline in social dominance while maintenance or even increase in warmth.
These trajectories are population-level averages. The data shows that while group trends are consistent, individual variation around those trends is substantial. Some people show dramatic personality change across adulthood while others show relative stability. The direction of individual change does not always match the population average.
Why people systematically underestimate their own change
The finding that people consistently underestimate personality change is not simply a matter of ignorance about psychology research. The researchers identify several mechanisms that produce this systematic bias.
The most fundamental is what psychologists call the end of history illusion: the documented tendency for people to recognize that they have changed substantially in the past while simultaneously believing they have now arrived at a relatively final version of themselves. Someone at 40 can clearly see how different they are from who they were at 20. But they tend to believe that who they are at 40 is approximately who they will continue to be for the rest of their lives.
This asymmetry appears to reflect a genuine feature of how people experience personal identity. Change in the past is visible in retrospect, organized into a narrative of development. Change in the future is harder to imagine because the future self, the one who will actually have done the changing, does not yet exist as a mental reference point.
A second mechanism is that personality traits feel stable from the inside. The way you experience yourself from moment to moment is more consistent than how you actually change over years. Daily variation is small. The trait-level shifts that accumulate into substantial change over a decade happen so gradually that they are essentially invisible from within a single life being lived.
A third mechanism is that the cultural framework for understanding personality emphasizes stability. The type-based systems most people are familiar with, Myers-Briggs, Enneagram, astrological personality, all assign people to fixed categories. Even the scientific Big Five framework, which explicitly allows for change, is usually communicated in terms of stable individual differences rather than developmental trajectories.
What the researchers say this means practically
The gap between what people believe and what actually happens has consequences that extend beyond an interesting psychological finding.
If people believe their personality is fundamentally fixed, they are unlikely to attempt deliberate change even when their current personality patterns are causing them problems. Research has shown that personality traits are meaningfully associated with health behaviors, relationship quality, career outcomes, and longevity. Neuroticism specifically is linked to worse health outcomes across the lifespan, and interventions that reduce neuroticism have been documented to produce real improvements in wellbeing. But if people believe high neuroticism is simply who they are, they are unlikely to attempt or sustain the interventions that could change it.
The researchers note that the gap also has implications for how personality research is communicated publicly. When scientists describe personality in terms of stable individual differences, they are accurately describing how personality works on short timescales. But the same language, applied to longer timescales, feeds the false belief that personality is essentially permanent.
“These results highlight a persistent gap between empirical evidence and public perceptions of personality traits,” the researchers wrote. “Effective communication about their malleability may help close it.”
What the study cannot establish
The longitudinal datasets used in the study come entirely from Western democratic countries: the United States, Germany, Australia, and the Netherlands. Whether the same patterns of personality change appear in other cultural contexts, with different life structures, different social expectations, and different distributions of life events, is not established by this research.
The modeled trajectories represent population averages, not individual predictions. The finding that neuroticism declines on average across adulthood does not mean that any given individual’s neuroticism will decline. Individual trajectories vary substantially around population means, and some individuals show the opposite direction of change from the average pattern.
The study also did not directly test the mechanisms that drive personality change. It documented that change happens and is larger than people believe, but did not randomly assign people to experiences that might drive change and measure the results. Whether the changes are driven by social roles, deliberate effort, biological maturation, or accumulated life experience remains a question for future research.
What the study establishes, across 166,971 people in four countries and a nationally representative American survey, is the core finding: people consistently underestimate how much their personality will change, across all five major traits, across every stage of adult life, without exception.
The self you believe you are becoming is likely less permanent than you think. The data is unambiguous about that.
The study, “Personality traits are less stable than people think”, was authored by Adam J. Wright, Marc D. Krämer, Peter Haehner, Christopher J. Hopwood, and Wiebke Bleidorn, and published July 27, 2026 in Communications Psychology.
Source: University of Zurich / UC Davis. DOI: 10.1038/s44271-026-00515-7
