Do personality traits remain stable over a lifetime?
To delve into individualism is to constitute what personality truly entails: a primary construct of identity. Referring to the APA Dictionary of Psychology, personality is a relatively permanent, internal characteristic used to predict patterns of behaviours, attitudes, feelings, and long-lasting habits. Adopting the Big Five model, the stability of these traits across an individual’s lifespan extends to their levels of openness, conscientiousness, extraversion, agreeableness, and neuroticism (Diener and Lucas, 2025). Arguably, there is general stability across adulthood, especially through a population scope, due to situational and dispositional interferences. However, this coexists with an extent of individual change and personality maturation, particularly during early developmental periods. In the prevailing era, there is limited convincing evidence illustrating the distinction between continuous and discontinuous traits into which people fit.
To begin, the debate centring personality stability and plasticity progressed from an early monolithic view to a much more diverse and complicated perspective. Early research suggested that heredity played a more crucial role in molding personality traits than the environment (Bouchard, 1994). Due to the established correlation between inherited characteristics and personality traits, the stability of personality traits from childhood is inherently implied since genes remain unchanged. In light of this, early research centralizing personality postulated stability, as the notion of ‘traits’ was to observe behavioural consistencies. For example, humans preserve the innate tendency to translate observed behaviour reoccurrences under linguistic labels (traits), suggesting that effective stabilization of traits is a result of repeated description (Allport and Odbert, 1936). Essentially, trait theory illustrates that traits exist because people noticed consistent behavioural tendencies (Allport, 1937). His theory is made up of the following triad of traits: cardinal (unique defining characteristic), central (general characteristics), and secondary (tentative characteristics), where each plays a role in shaping patterns of our behaviour. These
patterns then become stable internal dispositions: humans notice repeated behavioural patterns, so psychologists thereby label those patterns. Incorporating this, an individual who consistently emits sociability would conclusively portray “extraversion,” in accordance with early psychologists. Later came situationist critiques: psychologists argued that behaviour varies across environmental contexts (Madison and Mischel, 1968), and traits revealed situational inconsistency. This ideology reframed a nuanced modern perspective of personality stability and change: personality shows both stability and development, due to the interaction between traits and the environment (Caspi and Roberts, 2001).
Several emerging studies suggest that traits remain stable at the population level, especially in adulthood. Rank-order stability, otherwise the longitudinal consistency of an individual’s specific behaviour or trait, significantly strengthens before adulthood and plateaus in young adulthood (Bleidorn et al., 2022). Considering the post-childhood and adolescence era, individuals tend to fall under a constant relative trait position when compared to peers, and adulthood is the defining period for consolidating and stabilizing those trait rankings. This rank-order stability remains high and is maintained in later adulthood stages (Seifert et al., 2022), illustrating adult stabilisation in personality traits. Furthermore, the social investment model outlines that adult trait stabilisation occurs due to adopted social roles that merge into an individual’s identity, including work, family, and marriage; this implication thereby reduces trait variability, as people’s lives are increasingly structured around repeated behaviours that transform into habitual trait expressions (Roberts, Wood and Smith, 2005). Alternatively, traits have basic endogenous tendencies, where they are resistant to situational fluctuation and display dispositional continuity (McCrae and Costa, 1999). The environment may shape expression, but underlying biological trait tendencies remain enduring and become increasingly definite across adulthood.
Of possible reasons to pattern occurrence, stability is the result of formulated environments that reinforce existing traits an individual has. This is attained through four chronological individual-environment interactions: attraction, selection, manipulation, and attrition (Caspi, Roberts and Shiner, 2005). People are attracted to environments aligning with their dispositional tendencies, reinforcing the same trait pattern over time. Other people or institutions select individuals for roles based on similar/opposing traits, further strengthening the trait, supporting rank-order stability, and receiving trait-consistent roles during their lifetime. Individuals manipulate their environments to accustom their personalities and meet cognitive consonance, rather than the environment manipulating the person. Often, adults attrit environments that clash with their traits due to more individualized control of role choice, preserving the continuity of personality traits and the increase of stability.
Since the traits that lead people into environments are the same traits these environments reinforce, the corresponsive principle enables personality traits to have cumulative continuity (Roberts, Caspi and Moffitt, 2003).
Whilst personality remains relatively stable in structure, traits change on average level over time. Personality change is especially visible in early developmental transitions like adolescence (Soto and Tackett, 2015). Due to major emotional shifts, traits like social confidence rapidly fluctuate, as early life transitions shape the trajectory that can later feed into the maturity principle. Changing systematically with age, individuals tend to become more conscientious, socially dominant, and emotionally stable as adults, particularly at ages 20-40 (Roberts, Walton, and Viechtbauer, 2006). Additionally, traits are inherently dynamic, shifting in a predictable developmental pattern and providing a normative personality maturation. Even if people sustain their relative trait ranks when compared to peers, the overarching population average increases in maturity-related traits (peaking during young adulthood), which is referred to as the maturity principle. Despite these changes becoming less prevalent post the age of 40, trait change still persists in later adulthood, so adulthood can be considered to remain developmentally active (Roberts and Mroczek, 2008). Consequently, these changes of personality maturation span a full lifetime, beginning promptly in young adulthood but less prominently as individuals age. Through an opposing lens, it is important to note that not all people mature at the same rate (Durbin et al., 2015). Despite the forefront mean trend of increased maturity over time, there are outlying individual trajectories that report gradual emotional stabilisation and temporary regressions outside that average. Meanlevel maturation coexists with individual variability in developmental trait trajectories; the maturity principle aligns with an average trend rather than a pathway that every individual takes.
Traits are susceptible to change through social roles, where repeated long-term investment in adult institutions causes gradual personality maturation, especially in young adulthood, as outlined by the social investment theory (Roberts, Wood, and Smith, 2005). Despite adult roles forming internalised habitual patterns resembling dispositional traits, this reinforcement of behaviour can instead explain the increase of conscientiousness and agreeableness (maturity-related traits) in young adulthood: the primary age associated with the most role transitions. As these transitions occur at similar ages, they create normative personality development trends across populations. Furthermore, some trait changes are biological rather than situational, reflecting intrinsic maturational processes linked to neurological development (McCrae et al., 2000). Returning to the Big Five model, there are universal age-related increases in conscientiousness and agreeableness during brain development due to cognitive growth.
However, there is no clear answer between whether personality traits are stable or temperamental: both can be true simultaneously. Coexistence emerges because populations display high rank-order stability, whereas an individual emphasis can display the process of undergoing idiosyncratic trait change (Caspi, Roberts, and Shiner, 2005). Acknowledging the population macroscope, personality appears stable while still showing significant individual changes, with persistent trait relative standings but differing in the extent to which they change. Moreover, rank-order stability increases with age, where childhood possesses stunted emotional stability and late adulthood possesses optimal stability: the cumulative continuity principle (Roberts and DelVecchio, 2000). Therefore, adulthood reveals slower ongoing change and stronger continuity when compared to childhood. As people age, the more inherently predictable they become relative to peers, regardless of recurring change. Similarly, adulthood traits are highly stable yet never fully fixed in place; while adulthood has high rank-order stability, there is still measurable continued plasticity in response to major life events (Specht, Egloff, and Schmukle, 2011). Essentially, a feedback loop is displayed: personality traits predict which life events happen to an individual due to selection effects (e.g., extroverts are more likely to enter relationships), but this event can modify traits due to socialisation effects (e.g., an increase in agreeableness as relationships require patience and cooperation).
In summary, there is no clear distinction between personality traits remaining stable or dynamic in a lifetime. By reviewing rank-order stability and stabilisation of traits in adulthood, it can be argued that traits remain stable in a population. Conversely, mean-level change due to the maturity principle and individual fluctuations from the average trend can argue for trait plasticity. Rather, it is more precise to acknowledge the coexistence of both trait change and stability, where personality appears stable in a population while exhibiting significant individual changes due to both situational and dispositional explanations. Further elaborating this to increasingly prevalent digital environments, social media may influence trait development. There is a bidirectional relationship between neuroticism and social media use: people are enticed by content that matches existing traits, and this repeated exposure can influence an increase in negative traits (Andrews et al., 2020). Social media can, therefore, intensify existing trait trajectories through long-term, person-environment interactions and feedback loops, rather than simply stabilising or changing a personality trait.
