Psi man mascot


William James wrote in 1887, "In most of us, by the age of 30, the character has set like plaster, and will never soften again." Like most easy generalizations in psychology, this poses a challenge to researchers. Some would like to show that James is wrong: personality can change during adulthood.

However, research into personality change in adulthood largely supports James's conclusion. McCrae and Costa (1994) summarized research findings from "a score of longitudinal studies over the past 20 years" using "a wide variety of samples, instruments, and designs":

–Personality reaches final adult levels at about age 30. "Be­tween 20 and 30, both men and women become somewhat less emotional and thrill-seeking and somewhat more coop­erative and self-discip­lined—changes we might interpret as evidence of increased maturity. After age 30, there are few and subtle changes...

–Individual differences in personality traits, which show at least some continuity from early childhood on, are also essentially fixed by age 30.

–Generalizations about stability apply to virtually everyone. Men and women, healthy and sick people, blacks and whites all show the same pattern. (p.173)

Terracciano, Costa, and McCrae (2006) re-visited the issue using data from a 42 year longitudinal study. They re-affirmed the 1994 findings: overall stability after 30.

Roberts and Mroczek (2008) took note of several studies showing adult changes in levels of individual traits. They reported, "people show increased self-confidence, warmth, self-control, and emotional stability" with age. These changes occurred mostly between ages 20 and 40, which is consistent with McCrae and Costa's earlier findings.

Roberts and Mroczek (2008) added a caveat: The research was about averages, not individuals. There can be exceptions reflecting individual life events.

"In terms of individual differences in personality change, people demon­strate unique patterns of develop­ment at all stages of the life course. These patterns appear to be the result of specific life experiences that pertain to a person's stage of life."

What did William James write about personality in adulthood? What have researchers found?

Jack Block, of the University of California at Berkeley, is known for the longest and most thorough study of personality change in adulthood. Block's sample was first studied when they were teenagers, again in their mid-30s, and again their mid-40s.

Block used multiple, independent judges to assess personality. He took special care to prevent bias, concealing the identity of the subjects each time. Even so, the match between early and later personality assessments was striking.

Using this painstaking method­ology, Block found a striking pattern of stability [on] virtually every one of the 90 rating scales employed... The most self-defeating adolescents were the most self-defeating adults; cheerful teenagers were cheerful 40-year-olds; those whose moods fluctuated when they were in junior high school were still experiencing mood swings in midlife. (Rubin, 1981)

University of Minnesota sociologist Jeylan Mortimer compared self-ratings in questionnaires of a group of University of Michigan freshmen, first tested in 1962, with the same group in 1976: 15 years later. The outcome: "Very high stability." (Rubin, 1981).

What was the most stable trait in the two studies involving older adults?

Two studies involving older adults pro­duced similar results. A cross-section of ages (25 to 82) in the Boston study was tested, then tested again 10 years.

A Baltimore study was similar, with a different pattern of testing: three times, six years apart each time. The results, in both cases, showed personality and attitudes remained stable.

The most stable trait of all was introver­sion/extroversion or shyness. People who were talkative and cheerful at an early age were likely to remain that way.

What was true of people who did change personality in adulthood?

Rubin reported that one group of people did change their personalities during adulthood. These were people who took risks with major decisions in their adult life.

That makes sense. It suggests that one reason personality tends to remain stable after age 30 is that people settle into stable life styles that support their pre-existing personality patterns.

Changing Social Roles of Women

Changes in the way people live are due not only to individual decisions or personality change but to large scale social and genera­tional change. Scientists call generational patterns cohort effects. A "cohort" is a group of people born around the same time.

What is a cohort effect? What "remarkable trends" did scholars note in the 1970s?

Baby Boomers in the U.S. are one famous cohort. They hit adulthood during a rapid expansion of social science research in the 1970s, so there were many studies of how their lives differed from those before them. Dusen and Sheldon (1976) noted "three...remarkable trends" in the lives of women that occurred in the United States between 1950 and the mid-1970s when they wrote.

–Postponing marriage

–Postponing childbearing within marriage

–Reducing family size expectations

As noted earlier, the trend toward delaying marriage was (in retrospect) just beginning when these researchers identified it. The average age of first marriage has continued to rise to this day.

Reduced family sizes were partly a reflection of economic realities. As of 2017, it supposedly cost $233,000 to raise a child in the U.S.

No doubt that figure involves many assumptions not be true in particular cases, but in general, raising children is expensive in time and money. Given effective contra­ception, many people elect to have fewer children. This trend is seen in all developed countries, from Russia to Europe to Canada and Brazil.

In impoverished or less devel­oped regions of the world, the economic incentives are reversed. There, having a large family can give an economic advantage, providing more workers for small farms and family businesses. Those are places where birthrates continued to be as high as before.

Less developed areas with high birthrates tend to be areas where women have less power. For example, within India, the southern areas show the pattern of developed countries (lower birthrates, delayed marriage, fewer children).

Northern areas of India are completely different. Areas in the north have more male-dom­inated cultures. Women commonly have no reproductive choice, and birth rates remain high.

How did the lives of 1967 college graduates develop in unexpected ways?

Rosenfeld and Stark (1987) conducted interviews with women who had grad­uated from the University of Michigan in 1967, twenty years earlier. Compared to what they expected when they graduated, far more were working, and far more were in traditionally male jobs. 15% were divorced, and many felt torn between careers and families.

Stewart and Ostrove (1998) gathered data from five samples of college-educated female Baby Boomers, to see how they experienced middle age. About a third expressed regrets about early life decisions, particularly when they failed to pursue promising careers. For example, one wrote:

I would not have let my husband take sole responsibility for determining the course of our lives. His career has always been the only deciding factor in our lives, which has not been fair to me or the children. (p.1188)

Many of the women had exper­ienced some version of "mid-life crisis" (anxiety over unfulfilled plans or dissatisfaction with the direction of their lives). One 50 year old said, in an interview:

For me, 35 was the big waking up, looking around and saying, "Is this it? Is this all there is? Is this what life has dealt me?" If so, I'm getting up and doing something about it."

Women who had "gotten up and done something about it" were more satisfied with their lives, 10 or 15 years later, than women who expressed regrets but did nothing about it (Stewart and Ostrove, 1998).

Single-parent families became much more common in the United States in the 1980s and 1990s. That trend did not slow down until the mid-2000s.

The traditional family with a working father and stay-at-home mother was already a statistical minority by the 1950s. In some parts of the world, such as Eastern Europe and Russia, that pattern vanished in the 1930s or earlier, as husbands and wives were both expected to work.

In the U.S., a 2012 Pew Research survey showed only 18% of all adults agreed that "women should return to their traditional roles in society." Eight in ten adults (79%) rejected this idea. (Wang, Parker, and Taylor, 2013).

In Japan, the biggest change came after WW II, when women were granted the right to own property, inherit a family estate, marry and divorce freely, and vote. However, "Women were still expected to protect the household. Men were expected to be the breadwinners." Change is occurring, slowly, with more dual income households and more education among women (Kincaid, 2014).

In parts of the Middle East and North Africa where traditional cultures are emphasized, female labor participation rates are the lowest in the world. Illiteracy is common, and inequality may be mandated by religion (Moghadam, 2003).

In China, women face competing pressures from traditional and modern forces (Abraham, 2015). Researcher Cara Abraham wrote:

Throughout the tumultuous twentieth century, the family is still the basic unit of Chinese society and women are still expected to be wives and mothers. Many elements of tradi­tional Chinese culture survive and are interwoven with modern arrangements.

Family members demonstrate a tremendous respect and deference for each member, especially those in the eldest generation. Children are cherished. Marriages and deaths are marked by rituals that display the importance of continuing the family lineage.

The next generation of women is seeking a new identity in China. To what degree Chinese women will retain these traditions as they craft new identities in today's China is a sensitive matter that the next generation of women will need to resolve. (Abraham, 2015)

A survey commissioned by the World Bank interviewed men and women of 20 countries in 2012 (in separate single sex groups). They found a consistent pattern:

"The picture that emerged from every focus group across the 20 countries was of communities that continue to adhere to long-held gender norms of men as bread­winners and women in domestic roles. Children learn those norms early—'If we went to school, who would do the housework?' a girl from rural Tanzania asked.

"But within many homes and communities, particularly in cities, there is a clear relaxing of traditional norms as more men and women assume new responsibilities." (Boudet et al., 2012).

Age-Related Changes in Intellectual Functioning

Intellectual capabilities change as people grow older. IQ scores typically stay the same or get higher over the lifespan, although they may dip right before death (so-called terminal drop).

What changes most dramatically over the lifespan is not the overall quality of thinking but the speed of processing in some tasks (Bashore, Ridderinkhof, & van der Molen, 1998), the flexibility of learning, and the time of day when a person performs best.

What are some differences in the intellectual processes of young vs. old people?

May, Hasher, & Stoltzfus (1993) found a striking change in optimum time of day for intellectual activities, when comparing older and younger people. Older people typically described themselves as "morning people," saying their thought processes were clearest and sharpest in the morning.

Of 210 young people in this study, none of them described themselves as "Definitely Morning" people, if the option of describing themselves as "Moderately Morning" people was available. Of 91 old people, none of them described themselves as "Definitely Evening" or even "Moderately Evening" people.

How do the differences in "peak time of day" affect performance?

These differences affect perform­ance. When young and old people were compared on a variety of cognitive tasks in the morning (when old people were at their best) the two groups were identical in performance. When old and young people were tested in the evening, young people performed better.

What is "flexible" vs. "crystallized" intelligence?

Young people are generally superior to older people at flexible intelligence. They have an easier time learning new things or adapting to new circumstances. Older people are better at crystallized intelligence (Cattell, 1943).

Older people have a large store of exper­ience, which allows them to perform better in tests such as vocabulary tests that require an accumulation of know­ledge in a specialized area. When older people are asked to adopt a new information processing strategy that is unfamiliar to them, they may be unable to do so.

What did Hunt discover about his older subjects?

The distinction between flexible and crystallized intelligence showed up in research by Earl Hunt. Hunt (1983) studied different strategies of problem solving and found that people formed distinct groups.

Some (verbalizers) preferred to use language, and some (visualizers) preferred to use mental images. A revealing part of his research occurred when he asked the verbalizers to change their strategy.

The task was simple and the strategy for solving it is not difficult to describe: people had to visualize a scene like, "The plus sign is over the star." Then they had to match that description to a picture on a card.

Hunt found that all the college students he tested, even those who started out with the verbalizer strategy, were capable of adopting the imager strategy, and they benefited from it. Their scores went up.

However, Hunt found that this mental flexibility declined with age. Some of the older subjects seemed to be unable to use imagery, even when the technique was recommended to them.

Visualization ability declined with age, reaching a low in the oldest group, aged 56 to 67. In this group only 8 out of 17 subjects were able to use visual imagery in solving the problem.

The 9 who could not use imagery were not able to switch to this strategy even when it was described to them, and its advantages were pointed out. They had lost their flexibility of information processing.

How do the age-related changes affect job performance?

Age-related changes typically do not affect an older person's job performance, unless that person is required to learn something radically new. Slightly slower speed of processing is generally offset by experience with the job.


Abraham, C. (2015, September 23) Women's Roles in China. Retrieved from:

Bashore, T. R., Ridderinkhof, K. R., & Molen, M. W. van der (1998). Life-span studies of mental chronometry: Universal insights derived from chronopsycho­physiology. In N. Raz (Ed.), The Other Side of the Error Term: Aging and Development as Model Systems In Cognitive Neuroscience (pp. 197-259). Amsterdam, The Netherlands: Elsevier Science.

Brooks, D. (2007, October 9). The Odyssey Years. New York Times Retrieved from:

Cattell, R. B. (1943). The measurement of adult intelligence. Psychological Bulletin, 40, 153-193.

Hunt, E. (1983) On the nature of intelligence. Science, 219, 141-146.

Kincaid, C. (2014, June 22) Gender roles of women in modern Japan. Japan Powered. [blog] Retrieved from:

May, C. P., Hasher, L., & Stoltzfus, E. R. (1993). Optimal time of day and the magnitude of age differences in memory. Psychological Science, 4, 326-330.

Moghadam, V. M. (2003) Moderning women: Gender and social change in the Middle East [excerpt]. Retrieved from:

Munoz Boudet, A. M., Petesch, P., Turk, C., & Thumala, M. A. (2012) On norms and agency: Conversations with women and men in 20 countries. World Bank Documents and Reports [Working Paper] Retrieved from:

McCrae, R. R. & Costa, P. T. (1994) The stability of personality: Observation and evaluations. Current Directions in Psychological Science, 3, 173-175.

Roberts, B. W. & Mroczek, D. (2008) Personality trait change in adulthood. Current Directions of Psychological Science, 17, 31-35. doi:10.1111/j.1467-8721.2008.00543.x

Rosenfeld, A. & Stark, E. (1987, May). The prime of our lives. Psychology Today, p.62.

Rubin, Z. (1981, May). Does personality really change after 20? Psychology Today, pp.18-27.

Rubin, Z. (1981, November). The life changers. Psychology Today, pp.97-102.

Stewart, A. J. & Ostrove, J. M. (1998) Women's personality in middle age. Gender, history, and midcourse corrections. American Psychologist, 53, 1185-1194.

Terracciano, A., Costa, P. T., & McCrae, R. R. (2006) Personality Plasticity After Age 30. Personality and Social Psychology Bulletin, 32, 999-1009. doi:10.1177/0146167206288599

Wang, W., Parker, K., & Taylor, P. (2013, May 29) Chapter 2: Public views on changing gender roles. Pew Research Center [blog] Retrieved from:

Write to Dr. Dewey at

Don't see what you need? Psych Web has over 1,000 pages, so it may be elsewhere on the site. Do a site-specific Google search using the box below.