Personality Trait Change
in Adulthood
Brent W Roberts 1, Daniel Mroczek 2
___
Abstract
Recent longitudinal and cross-sectional aging research has shown that personality
traits continue to change in adulthood. In this article, we review the evidence for
mean-level change in personality traits, as well as for individual differences in change
across the life span. In terms of mean-level change, people show increased
selfconfidence, warmth, self-control, and emotional stability with age. These changes
predominate in young adulthood (age 20–40). Moreover, mean-level change in
personality traits occurs in middle and old age, showing that personality traits can
change at any age. In terms of individual differences in personality change, people
demonstrate unique patterns of development at all stages of the life course, and
these patterns appear to be the result of specific life experiences that pertain to a
person’s stage of life.
Keywords: personality development, personality traits, mean-level change,
individual differences in change
Personality traits are defined as the relatively enduring patterns of thoughts, feelings,
and behaviors that distinguish individuals from one another. Whether personality
traits continue to develop in adulthood depends in part on how one defines “relatively
enduring.” In the past, some researchers took that phrase to mean—and the
empirical literature to indicate—that personality traits stopped changing in adulthood
(McCrae & Costa, 1994). Since 1994, cross-sectional and longitudinal studies of
personality-trait change in adulthood have forced a reevaluation of the assumption
that personality traits do not change in adulthood (e.g., Mroczek & Spiro,
2003; Roberts, Walton, & Viechtbauer, 2006; Srivastava, John, Gosling, & Potter,
2003). Research now shows that personality traits continue to change in adulthood
and often into old age, and that these changes may be quite substantial and
consequential. In this article, we provide an overview of the evidence for personality-
trait change in adulthood and outline some of the possible reasons for these
changes. Before we discuss these findings further, we describe what we mean by
change.
___
DEFINITIONS OF PERSONALITY CONTINUITY
AND CHANGE
Researchers often fail to clarify what they mean when they describe personality as
consistent or changeable. Part of the difficulty arises from the multiple indices for
tracking continuity and change—such as mean-level change, rank-order consistency
(relative ordering of people over time), structural consistency (e.g., similar factor
structures over time), and individual differences in change. A complete understanding
of personality continuity and change can only come from a thorough examination of
multiple indices, as they are often independent of one another and therefore provide
different answers to the question, “Do personality traits change?” (Roberts, Wood, &
Caspi, in press).
In this article, we focus exclusively on mean-level change and individual differences
in change, because these indices most directly reflect increases or decreases in
traits at the population level (mean-level change) and at the individual level
(individual differences in change), respectively. Mean-level change refers to gains
and/or losses in specific personality traits over a pre-specified period of time and age
in the life course for a population of individuals. Individual differences in change
reflect deviations from these overall, mean-level patterns. That is, some people will
change much more or less than the norm.
___
MEAN-LEVEL CHANGES IN PERSONALITY
TRAITS
Recent cross-sectional and longitudinal research has converged on the finding that
personality-trait development can and does occur in all age periods of adulthood,
including old age. Specifically, cross-sectional research has shown that middle-aged
individuals tend to score higher than young adults on agreeableness and
conscientiousness and lower on extraversion, neuroticism, and openness
(Srivastava, John, Gosling, & Potter, 2003). Moreover, within middle age, 60-year-old
participants scored higher than 40-year-old participants on most dimensions (though
it should be noted that these results may be confounded by cohort effects such as
historical events or changes in cultural climate).
Longitudinal studies, mostly of Western cultures, have found strikingly similar results.
Changes in mean levels of personality traits were recently examined in a meta-
analysis of 92 longitudinal studies covering the life course from age 10 to 101
(Roberts, Walton, & Viechtbauer, 2006). As in the cross-sectional studies, significant
mean-level change in all trait domains was found at some point in the life course, and
statistically significant change was found in 75% of personality traits in middle age
(40–60) and old age (60+). Clearly, personality traits continue to develop in
adulthood.
Graphs showing cumulative change across the life course are shown in Figure 1. The
findings were organized according to a modified Big Five framework (e.g.,
Extraversion, Agreeableness, Conscientiousness, Emotional Stability, and Openness
to Experience) in which the domain of Extraversion was further divided into the
subdomains of social vitality (e.g., gregariousness) and social dominance (e.g.,
assertiveness). The results showed that people became more socially dominant over
time, especially in young adulthood. Social vitality showed small increases in
adolescence and then small decreases late in life. Although much of the change on
agreeableness was positive, the increase was only statistically significant in old age.
People showed little change on conscientiousness in adolescence but then showed
remarkable gains in young adulthood and midlife. Emotional stability showed steady
increases through midlife. Finally, individuals demonstrated gains in openness to
experience in adolescence and then equivalent declines in old age. The cumulative
amount of personality-trait change across adulthood for several trait domains
exceeded one full standard deviation.
Fig. 1.
Change in personality traits over time for six trait domains. These graphs were
created by adding average amounts of standardized mean-level change from
separate decades of the life course together, under the assumption that personality-
trait change may be cumulative. Extraversion is broken into its constituent
subdomains of social vitality and social dominance.
Several important conclusions about personality development can be drawn from
these studies. First, most mean-level personality-trait change occurs between the
ages of 20 and 40. This contradicts the widely held perspective that the most
interesting years for studying personality development are either early or late in life.
Rather, young adulthood appears to be the most important period. We believe that
this finding opens a new area of focus in developmental science, as the causes and
mechanisms responsible for personality-trait change in young adulthood have
received little empirical or theoretical attention.
Second, personality traits continue to change, even in old age. One of the precepts of
a life-span orientation is that humans are open systems (e.g., Baltes & Nesselroade,
1973). That is, people retain the capacity to change at all ages. The changes in
personality traits in middle and old age are by no means dramatic, but nonetheless
they show that the life-span orientation applies to personality traits and that
personality is not set like plaster at any point in the life course.
Third, time has a positive effect on personality-trait change. Studies that follow
people for a longer period of time show larger mean-level changes. The positive
association between time and mean-level change is important for theoretical models
of human nature. A common assumption is that personality traits act like metabolic
set points. People may stray briefly from their biological propensity, but they will then
tend to drift back to their genetically driven set point. Under these types of models,
one would expect to find a negative or null association between time and mean-level
change, because any change will represent short-term fluctuations that disappear as
people return to their biologically driven set point. However, time is positively
associated with personality-trait change, which indicates that a strong set-point
model does not apply to personality-trait development. That is, when people change,
then tend to retain the changes in personality traits for the remainder of their lives.
Fourth, the direction of change is clearly in the positive direction. With age, people
become more confident, warm, responsible, and calm—or what some have
described as socially mature (Roberts & Wood, 2006). Social maturity is equated with
the capacity to become a productive and involved contributor to society. Moreover,
those who develop the cardinal traits of psychological maturity earliest are more
effective in their relationships and work and lead healthier and longer lives (Roberts,
Kuncel, Shiner, Caspi, & Goldberg, 2007).
The recent findings motivate a new generation of questions concerning why
personality traits change more in young adulthood than in other periods of the life
course and what the implications of the mostly positive trend in personality-trait
change might be. Of course, one of the realities of any sweeping generalization is
that it does not apply to all people. Much of this research needs to be replicated in
non-Western cultures before firm conclusions are drawn. Moreover, some people fail
to conform to the general trends by not changing at all, being more accelerated in
their change patterns with time, or changing in ways that contradict normative trends.
These deviations are captured with the concept of individual differences in
personality-trait change.
___
INDIVIDUAL DIFFERENCES IN PERSONALITY-
TRAIT CHANGE IN ADULTHOOD
Imagine tracking changes in extraversion for 10 years for three individuals. Lydia
shows no change over the 10 years. Olivia decreases a full standard deviation over
the same period. And Will increases a half of a standard deviation. These three
individuals illustrate the concept of individual differences in change: Some people go
up, some go down, and some remain the same. Moreover, among those who do
show change, there is variability in how much change occurs. Olivia and Will both
changed, but also varied in amount of change (one vs. one half of a standard
deviation).
This concept of individual differences in change—a corner-stone of lifespan-
developmental theory (Baltes & Nesselroade, 1973)—refers to the gains or losses (or
lack thereof) in absolute levels of a personality trait that an individual experiences
over time. These are changes that deviate from the population mean-level pattern of
change. Over the past 10 years, a growing number of researchers have placed the
concept of individual differences front and center in the study of personality
development (Mroczek & Spiro, 2003; Roberts, 1997). This new perspective holds
that personality change (and stability) is an individual-differences variable and that a
complete understanding of personality development is only possible if individual
differences in personality-trait change are examined alongside more traditional
indices of development.
The key empirical hurdle that needs to be addressed is to determine whether
individual differences in change are real or whether they simply represent error in
measurement (Watson, 2004). The need to answer this has drawn many personality-
development researchers to use techniques for gauging the amount and pattern of
change over time. One index drawn from clinical psychology is the Reliable Change
Index (RCI; Roberts, Caspi, & Moffitt, 2001). The RCI gauges the amount of change
that occurs against the amount of change that could be expected given the fact that
measures are not perfectly reliable. Using the RCI index, researchers have
established the existence of reliable individual differences in change in childhood,
adolescence, young adulthood, and middle age (Roberts, Wood, & Caspi, in press).
Alternatively, a better procedure for establishing the existence of reliable individual
differences in change is growth modeling, which relies on multiple waves of data to
make more precise estimates of change (Singer & Willett, 2003). Growth models of
personality traits using multiple measurement occasions have grown in number over
the past 10 years (e.g., Helson, Jones, & Kwan, 2002; Mroczek & Spiro, 2003; Small,
Hertzog, Hultsch, & Dixon, 2003). Together, these studies have established that the
Big Five traits show unmistakable variability across individuals in direction and rate of
change.
Once the existence of reliable individual differences in personality-trait change has
been established, the compelling question becomes why these changes occur. A
number of studies have shown that life and work experiences are associated with
changes in personality traits (for review, see Roberts, Wood, & Caspi, in press). For
example, people who experience more successful and satisfying careers in young
adulthood increase disproportionately on measures of emotional stability and
conscientiousness (Roberts, Caspi, & Moffitt, 2003). Men who get remarried in
middle age show decreases in neuroticism (Mroczek & Spiro, 2003; women were not
studied). Not all experiences are for the better. People who conduct problematic,
counterproductive activities at work, such as theft, aggression, and malingering, are
prone to decrease on measures of conscientiousness and emotional stability
(Roberts, Walton, Bogg, & Caspi, 2006).
One of the advantages of the individual-differences approach is that it may provide
insights as to why people show the general, mean-level trends in personality trait
change described above. If most, but not all, people move through specific life
experiences at particular times in the life course, then these experiences may be
largely responsible for the general trend of people becoming more mature, especially
in young adulthood. Specifically, it has been proposed that the quasi-universal trend
to invest in the social roles tied to one’s career, family, and community in young
adulthood—a process described as social investment—serves as a catalyst for
personality-trait change (Roberts & Wood, 2006). Consistent with the fact that such
role transitions may help to explain mean-level changes in personality traits, several
longitudinal studies have shown that participating in a stable marriage and committed
career track are associated with increases in social dominance, conscientiousness,
and emotional stability (Roberts & Wood, 2006).
One of the unique aspects of the study of individual differences in change is that
personality traits are considered outcomes, not predictors (as they are typically
viewed). For example, in studies like Roberts (1997), personality traits are seen as
the consequence of work experiences. One reason to consider personality traits as
dependent variables is that personality-trait change may be quite consequential for
people. Mroczek and Spiro (2007) demonstrated that long-term increases in
neuroticism were predictive of mortality in an 18-year survival analysis (the study
used men; women were not available in this study). Those who started high on
neuroticism (above the sample median) and increased over 10 years had higher
mortality, controlling for age, depression, and physical health.
___
CONCLUSION
Exciting conclusions and questions are being drawn from the recent findings on
personality-trait development. Personality traits are developmental constructs, even
in adulthood. That personality traits change in adulthood and do so in a positive
direction should not be taken as the final statement on personality development in
adulthood. Future research will need to incorporate more methodological diversity, as
too many longitudinal studies rely solely on self-reports of personality traits (Watson,
2004). There is a paucity of true cross-cultural longitudinal research, since most
longitudinal studies arise from the United States or Europe. Longitudinal studies of
people from the Asian and African continents, for example, would be invaluable to
determining just how well these patterns generalize and whether they are truly
universal. Also, our current understanding and assessment of life experiences and
key developmental environments is impoverished, relying too heavily on simple
demographic variables. The field of personality development desperately needs a
greater understanding of the developmental experiences that are consequential for
personality traits across the life course. Finally, these findings open the door for
research identifying the causal mechanisms responsible for why personality-trait
change occurs. Life experiences, genes, and other constructs such as cognitive
ability and life goals may all be important mechanisms. We look forward to seeing
these issues addressed in the next generation of longitudinal research.
___
Recommended Reading
Mroczek, D.K., & Spiro, A., III. (2003). (See References). A representative study that
illustrates original research on growth modeling and personality-trait change.
Mroczek, D.K., & Spiro, A., III. (2007). (See References). The first study to show that
individual differences in change in neuroticism predicts mortality.
Nesselroade, J.R. (1991). Interindividual differences in intraindividual change. In L.M.
Collins & J.L. Horn (Eds.), Best methods for the analysis of change (pp. 92–105).
Washington, DC: American Psychological Association. A classic paper defining
individual differences in change, their importance, and the multiple ways of
conceptualizing and measuring them.
Roberts, B.W.,Walton, K., & Viechtbauer, W. (2006). (See References). A
comprehensive overview of mean-level change in personality traits.
Helson, R., Mitchell, V., & Moane, G. (1984). Personality and patterns of adherence
and nonadherence to the social clock. Journal of Personality and Social Psychology,
46, 1079–1096. A historical classic—one of the first papers to raise attention about
the relation between life experiences and personality-trait development in adulthood.
___
Acknowledgments
This research was supported by Grants R01 AG21178 and R01 AG1846 from the
National Institute of Aging. We would like to thank Teresa Cardador, Jennifer Smith,
and Josh Jackson for comments on earlier drafts of this article.
___
REFERENCES
1. Baltes PB, Nesselroade JR. The developmental analysis of individual
differences on multiple measures. In: Nesselroade JR, Reese HW, editors.
Life-span developmental psychology: Methodological issues. New York:
Academic press; 1973. pp. 219–251. [Google Scholar]
2. Helson R, Jones CJ, Kwan SY. Personality change over 40 years of
adulthood: Hierarchical linear modeling analyses of two longitudinal samples.
Journal of Personality & Social Psychology. 2002;83:752–766. [PubMed]
[Google Scholar]
3. McCrae RR, Costa PT. The stability of personality: Observation and
evaluations. Current Directions in Psychological Science. 1994;3:173–
175. [Google Scholar]
4. Mroczek DK, Spiro A., III Modeling intraindividual change in personality traits:
Findings from the Normative Aging Study. Journals of Gerontology B:
Psychological Sciences and Social Sciences. 2003;58:153–165. doi:
10.1093/geronb/58.3.p153. [DOI] [PubMed] [Google Scholar]
5. Mroczek DK, Spiro A., III Personality change influences mortality in older
men. Psychological Science. 2007;18:371–376. doi: 10.1111/j.1467-
9280.2007.01907.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
6. Roberts BW. Plaster or plasticity: Are work experiences associated with
personality change in women? Journal of Personality. 1997;65:205–232. doi:
10.1111/j.1467-6494.1997.tb00953.x. [DOI] [PubMed] [Google Scholar]
7. Roberts BW, Walton K, Bogg T, Caspi A. De-investment in work and non-
normative personality trait change in young adulthood. European Journal of
Personality. 2006;20:461–474. [Google Scholar]
8. Roberts BW, Caspi A, Moffitt T. The kids are alright: Growth and stability in
personality development from adolescence to adulthood. Journal of
Personality and Social Psychology. 2001;81:670–683. [PubMed] [Google
Scholar]
9. Roberts BW, Caspi A, Moffitt T. Work Experiences and personality
development in young adulthood. Journal of Personality and Social
Psychology. 2003;84:582–593. [PubMed] [Google Scholar]
10. Roberts BW, Kuncel N, Shiner R, Caspi A, Goldberg LR. The power of
personality: A comparative analysis of the predictive validity of personality
traits, SES, and IQ. Perspectives on Psychological Science. 2007;2:313–
345. doi: 10.1111/j.1745-6916.2007.00047.x. [DOI] [PMC free article]
[PubMed] [Google Scholar]
11.Roberts BW, Walton K, Viechtbauer W. Patterns of mean-Level change in
personality traits across the life course: A meta-analysis of longitudinal
studies. Psychological Bulletin. 2006;132:1–25. doi: 10.1037/0033-
2909.132.1.1. [DOI] [PubMed] [Google Scholar]
12. Roberts BW, Wood D. Personality development in the context of the
Neo-Socioanalytic Model of personality. In: Mroczek D, Little T, editors.
Handbook of personality development. Mahwah, NJ: Erlbaum; 2006. pp. 11–
39. [Google Scholar]
13. Roberts BW, Wood D, Caspi A. Personality development. In: John OP,
Robins RW, Pervin LA, editors. Handbook of personality: Theory and
research. 3rd ed. New York, NY: Guilford; (in press) [Google Scholar]
14. Singer JD, Willett JB. Applied longitudinal analysis: Modeling change
and event occurrence. New York: Oxford University Press; 2003. [Google
Scholar]
15. Small BJ, Hertzog C, Hultsch DF, Dixon RA. Stability and change in
adult personality over 6 years: Findings from the Victoria Longitudinal Study.
Journals of Gerontology B: Psychological Sciences & Social Sciences.
2003;58:166–176. doi: 10.1093/geronb/58.3.p166. [DOI] [PubMed] [Google
Scholar]
16. Srivastava S, John OP, Gosling SD, Potter J. Development of
personality in early and middle adulthood: Set like plaster or persistent
change? Journal of Personality and Social Psychology. 2003;84:1041–1053.
doi: 10.1037/0022-3514.84.5.1041. [DOI] [PubMed] [Google Scholar]
17. Watson D. Stability versus change, dependability versus error: Issues in
the assessment of personality over time. Journal of Research in Personality.
2004;38:319–350. [Google Scholar]
END
