Personality Can Be Stable Without Being Permanent
Personality is often thought of as a fixed, unchanging essence. However, a landmark 2026 study challenges this notion by revealing that while personality traits remain relatively stable, they are far from permanent. At the heart of this research is a comparison between what Americans expect will change in personality traits from age 15 to 90 and actual longitudinal data drawn from extensive panel studies across multiple countries.
The study, published in the peer-reviewed journal Communications Psychology, combined two major components. First, 887 US adults were surveyed to estimate how much the Big Five personality traits—extraversion, agreeableness, conscientiousness, neuroticism, and openness to experience—and 20 other personal characteristics change throughout life. Then, researchers analyzed data from 166,971 individuals across Germany, Australia, the United States, and the Netherlands, collected over decades through eight long-running panel studies.
Crucially, the headline figure—that the public underestimates personality trait change by about 90%—refers to a median rate of underestimation in net change across different analytical models. Participants provided a single, holistic judgement of change across the entire lifespan rather than predicting year-to-year shifts. Thus, this figure captures a consistent bias in how personality change is perceived rather than individual prediction errors at specific ages.
The Big Five: Dimensions, Not Fixed Categories
The Big Five personality traits are best understood as continuous dimensions. For example, extraversion varies on a spectrum rather than fitting people neatly into “extravert” or “introvert” boxes. This dimensional approach contrasts with categorical personality systems like the Myers-Briggs Type Indicator, which can misleadingly suggest personality types are rigid and unchanging.
While the Big Five avoid the pitfalls of type-based systems, people often treat traits as fixed parts of their identity. Statements like “I am not organised” or “He has never been open to new things” imply permanence. Such trait descriptions can inadvertently become forecasts, fostering the belief that personality does not meaningfully change over time.
What the Public Survey Asked
The research team, led by Amanda Wright from the University of Zurich, recruited a demographically representative sample of US adults through Prolific. After quality checks, 887 participants remained, averaging 45 years of age. They were asked to rate how much various characteristics change on average in the population between ages 15 and 90, using a scale from 0 (no change) to 11 (complete change).
The characteristics included the Big Five traits alongside 20 other variables related to identity, health, relationships, work, finances, leisure, and social life. Among these were self-esteem, life satisfaction, optimism, loneliness, physical health, sleep, exercise, income, relationship satisfaction, socialising, and volunteering.
Participants rated extraversion as the most stable Big Five trait (average rating 4.58) and conscientiousness as the most changeable (5.87). The average rating across all five traits was 5.37, placing them among the most stable traits in the survey. Importantly, respondents acknowledged change but judged personality traits to shift less than nearly all other characteristics.
Empirical Data From Eight Long-Running Panels
To ground these perceptions in data, the researchers analyzed eight major panel studies: the German Socio-Economic Panel, Australia’s HILDA study, the US Health and Retirement Study, the Dutch LISS panel, Midlife in the United States, the US National Longitudinal Survey of Youth, the German Family Panel, and the Wisconsin Longitudinal Study.
These datasets included 166,971 individuals, each typically measured across roughly 9.5 waves of data collection, with some followed for up to 40 waves. Data collection spanned from 1984 to 2024, covering ages 14 to 111. Given that no panel tracked individuals continuously from adolescence to old age, the study employed hierarchical age-period-cohort models to estimate average age trajectories while controlling for survey year and birth cohort effects.
By standardizing variables, the researchers enabled direct comparison of change magnitudes across diverse domains, from personality traits to income and health.
Net Movement vs. Cumulative Movement
The study differentiated between two types of change. Net change measures the difference in average trait scores between ages 15 and 90. Cumulative change sums the absolute magnitude of year-to-year movements, capturing fluctuations that net change might obscure.
For example, extraversion declined by 0.784 standard deviations on average, openness by 0.540, and neuroticism by 0.400, while conscientiousness and agreeableness increased by 0.484 and 0.221 respectively. These figures reflect population averages, not individual trajectories—some individuals may change more, less, or in opposite directions.
Cumulative change highlighted even more movement. Conscientiousness exhibited 1.91 standard deviations of cumulative change across the 75-year span, ranking it among the most dynamic variables—outpaced only by socialising frequency, income, health limitations, and sleep duration. Annual average increments were small (e.g., 0.026 standard deviations for conscientiousness) but meaningful when accumulated over decades.
The 90% Underestimation Figure: Robustness and Nuance
Wright and colleagues tested multiple analytical variants, comparing perceived and empirical change using standardized effect sizes, rankings, net and cumulative measures, and corrections for measurement reliability. They also restricted some analyses to US-only datasets to better align with the belief survey’s demographic.
Across these approaches, the median underestimation rate for Big Five net change was about 90%, and for cumulative change, it reached 100%. Every trait was underestimated in the full four-country analysis, and underestimation of cumulative change was universal even in US-only checks.
Importantly, this 90% figure summarizes model-based comparisons and is not a direct measure of how many individuals provided inaccurate estimates or failed to predict specific year-to-year changes.
The public’s judgments were not random guesses. Perceived change correlated moderately with empirical data across the whole set of variables (r = 0.59 for net change; r = 0.55 for cumulative change). People generally understood which life domains change more or less, but personality traits stood out as exceptions—consistently judged to be more stable than they actually are.
Reconciling Average Change With Recognizable Individuals
The study’s focus on mean-level change does not address rank-order stability, which reflects whether individuals maintain their relative positions within a group. For instance, if an entire cohort becomes more conscientious with age, the most conscientious individuals at 15 may still rank highly at 90, preserving relative stability amid average change.
Moreover, mean-level changes do not imply drastic transformations. A modest decline in extraversion over decades does not mean all outgoing teenagers become solitary elders; it means average trait expressions shift with age.
This nuance echoes findings from a 50-year American study of personality maturation, which showed that people retained meaningful continuity from adolescence to late middle age even as they grew more agreeable, conscientious, and emotionally stable on average. Stability and development coexist harmoniously.
Limitations and Contextual Boundaries
All eight panel studies originated from Western democratic countries, and the perception survey sampled only US adults. Cultural factors heavily shape beliefs about personality and the “true self,” so these findings may not generalize globally.
Most variables were self-reported, with some multi-item scales adjusted for reliability. Nonetheless, some single-item measures lacked comparable corrections. The age-period-cohort modelling, while sophisticated, remains a statistical model rather than a continuous longitudinal record of a single population cohort.
Crucially, the study describes average trends and does not imply that any trait can be rapidly changed, that life events will always reshape personality, or that interventions will reliably produce desired personality shifts. No experimental manipulation was involved; the results reflect observational data.
The authors have made their preregistrations, survey data, analysis code, and supplementary materials publicly available, enhancing transparency and trustworthiness.
Traits Are Tendencies, Not Sentences
The enduring belief in fixed personality traits partly arises because traits offer simple explanations for behavior. Saying someone “is just disorganised” can prematurely end inquiry into underlying causes or potential for change.
Longitudinal evidence points to a more nuanced understanding: personality balances meaningful continuity with gradual development. The degree of change varies by trait, life stage, individual differences, and environmental factors.
Just as people accept that work, income, health, relationships, and satisfaction evolve over time, it is equally important to recognize that the person experiencing these changes is not standing still either.
For more detailed insights, see the original study and analysis Here.
