The once popular idea that our personality becomes “set like plaster” by the age of 30 has been refuted by studies showing that we do change — and can even purposefully change ourselves. Many studies have identified shifts in Big Five traits across the lifespan. However, the often inconsistent results have made for ongoing controversy about how personality typically changes with age.
Now a new analysis of data from 16 longitudinal studies, with a total sample of more than 60,000 people from various countries, reveals some important insights. The work, published by Eileen Graham at Northwestern University, Chicago, and her colleagues in the European Journal of Personality Research, suggests that there are indeed some clear patterns of change through middle age and into older age for at least four of those five traits.
For all the studies included in the analysis (from the US, the Netherlands, Sweden, Scotland and Germany), participants had completed an assessment of at least a subset of the Big Five traits (extraversion, agreeableness, neuroticism, openness and conscientiousness) on at least three separate occasions.
The researchers then compared the results, to consider the balance of evidence for the extent and direction of personality change over time. The way they did this was important. The team used a “coordinated integrative data analysis”, which allowed them to look for patterns in findings, but as the data was not pooled, they could also identify variations between different studies, and explore possible reasons for differences in results. They also looked for any links between personality changes and the participant’s sex and age group (under or over 60 years old) at the time of their first assessment.
The findings from the various studies were not all in agreement with each other. However, the team found fairly consistent evidence for some clear patterns of change for all of the traits, except agreeableness.
Both extraversion and conscientiousness showed a fairly steady pattern of decline with time. For conscientiousness, this decline was clearest among participants who were over 60 when they took the first personality test. This finding is consistent with several theories about personality change with age, the authors note, including the idea that for younger and middle-aged people, it’s advantageous to exhibit pro-social traits like extraversion and conscientiousness, but as social demands begin to wane in older age, so might these traits. Indeed, the team also found that openness, another prosocial trait, was stable through middle adulthood, before decreasing in older age.
Neuroticism showed a different, U-shaped pattern. Overall, the data suggests that neuroticism decreases through most of adulthood, then increases again in older age. This is consistent with the idea that in old age, we tend to become anxious about terminal illnesses and death.
The team found that sex was not relevant, except for neuroticism: females had slightly steeper declines through middle adulthood than males.
Nearly all of the samples also revealed some individual differences in changes for all five personality traits — so, though there were these overall trends in changes, not everyone in each sample, or across the samples, changed at the same rate, or even in the same direction.
More work is now needed to understand why. As the researchers write, “people change differently on different traits, personality is not stable for everyone across the lifespan (but is for some people), and accounting for or explaining these changes is difficult.”
More generally, though, the team would like to see more psychology studies using this approach. By not merging the individual data sets, this type of meta-analysis can not only help to clarify the picture of results in a given field, but also preserve the differences between studies, which could help with the increasingly popular exploration of differences — as well as similarities — between people.