Can People Change Their Personalities?

On the possibility of personality change

In my very first Substack essay, Understanding Human Personality, I wrote the following:

We speak of people having particular traits, but also of being of a certain type; when a person is acting strangely, we say they’re not themselves, and after not seeing someone for many years, we might notice that they’re no longer the same person. All of this suggests that personality not only refers to who a person is, but who they are not, and that a person’s personality may change in certain situations or across time.

I go on to suggest that there’s academic controversy surrounding these points, and this is true. While the existence of personality traits is now virtually incontestable, the idea of personality types has fallen out of favour, and the possibility of personality traits changing remains an open question. Personally, I fall on the side of believing that personality can change. Today I want to explain why.

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Situational Change

In 1968, psychologist Walter Mischel (most well known for his marshmallow experiment) published a book called Personality and Assessment, which challenged the prevailing view that personality remains the same from situation to situation. Drawing on empirical research, Mischel showed how different situational factors can lead people to act in very different ways. For example, a person may act in a passive and agreeable way around their parents, and then act more assertively at work. This seems obvious to us now, but at the time it caused quite a stir—personality theorists who lived through this period describe Mischel’s book as having had “the effect of a bombshell”¹, and it supposedly led many researchers to abandon the field entirely. It was another two to three decades before personality psychology found its feet.

Walter Mischel (1930-2018) was an important figure in the history of psychology. His 1968 book, Personality and Assessment, led to a radical shift in the trajectory of personality research.

Researchers were eventually able to re-establish the existence of personality traits in the form of the Big Five, but had to account for this situational variation. They concluded that a person’s score on a measure of a particular trait/behaviour essentially represented an average of that person’s behaviour across time and situations. The final synthesis looks something like the ‘set point theory’ used to explain human bodyweight fluctuation: we all have a default weight range around which our body tends to sit, and various internal and external factors cause day-to-day variation within this range. Personality works the same way. I might be a generally agreeable person, but there will be days on which I’m slightly more or less agreeable depending on the circumstances.

So personality can change—within a limited range, under limited circumstances. But otherwise, our personality remains relatively stable over time. Right?

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Change Over the Lifespan

Nowadays, most personality psychologists agree that there’s situational variation in personality traits. Many have argued that this is the extent of things, though, and that personality otherwise remains stable across the lifespan. Research by Brent Roberts, Daniel Mroczek and others in the area of personality development—the study of personality change over the lifespan—now offers a credible alternative to this view.

In a 2008 review of the literature on adult personality change, Roberts and Mroczek concluded that there’s good evidence for Big Five personality development over the lifespan. The most significant changes seem to occur between ages 20-40; the typical pattern is an increase in Conscientiousness, Agreeableness, and the Extraversion sub-trait ‘Social Dominance’, as well as a decrease in Neuroticism. This doesn’t mean that everyone goes through these changes—the authors acknowledge that there is substantial individual variation in the amount and trajectory of personality development—and it also doesn’t mean that personality changes only occur during this life stage. But it does show a general trend in young adulthood toward traits that are typically viewed as more positive, and these changes remain relatively stable from age 40 onwards.

These findings held up 13 years later. A 2021 review by Wiebke Bleidorn and colleagues agreed that, while personality remains stable in the medium-term, significant change does occur over the long-term at all stages of life. Again (excluding childhood and adolescence), significant personality development is seen between ages 20-40, mostly in Neuroticism, Conscientiousness, and Agreeableness. However, with an additional 13 years of research on personality in older adults, the authors noted an interesting trend that echoes Shakespeare’s famous observation on man’s “second childishness”²—in very old age, there is a reversal of the changes seen in our youth, with a reduction in Agreeableness, Extraversion, and Conscientiousness, and an increase in Neuroticism. So while personality stays relatively stable from age 40 onwards, there’s always flexibility in these traits, and toward the end of life personality once again goes through a period of significant change.

Shakespeare recognised that people change over the course of their life, and famously referred to old age as a “second childishness”. Are personality psychologists finally catching up to folk wisdom? (Picture: Ages of Man, a 1482 woodcut by an unknown artist).

Why do these changes occur? As with most psychological constructs, the answer seems to be a combination of nature and nurture. There’s a clear genetic element to personality, and genetic factors likely also contribute to individual personality development over time. We know that the brain continues to develop into our 20s, so personality change at this time must be at least partly related to the various emotional, cognitive, and behavioural changes seen throughout this period.

Personality can also be impacted by life experiences. The research is not yet clear on which experiences cause personality change, but there’s good evidence for two: our first significant romantic relationship (linked to increased Extraversion and reduced Neuroticism), and the transition from school into work or university (linked to increased Agreeableness, Conscientiousness, Openness, and reduced Neuroticism). A recent meta-analysis found that clinical interventions such as medication and therapy can also cause change in the domains of Neuroticism and Extraversion, which suggests that it might be possible to intentionally change one’s personality—to read about some recent attempts at intentional personality change, see here and here.

The research in this area is still developing, so I’m sure I’ll have more to say on this in the future. But it’s clear that personality shows noticeable change both situationally and across time, and evidence is now emerging to support the idea of intentional personality change.

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Character Re-Adaptation

I previously introduced the term ‘Characteristic Adaptation’, a personality construct that refers to the socioculturally-influenced expression of our personality traits³. Before I say more, I want to make an executive decision on the use of the term Characteristic Adaptation. I’m done with it—it’s a clunky term, and it makes my brain glaze over whenever I see it. From now on, I’ll be using the term Character Adaptation. It’s a subtle change, but to my mind, much more intuitive.

In a previous essay, I introduced the ‘Jock’ archetype as an example of a Character Adaptation. Here we see how CAs can be broken down into Interpretations, Strategies, Goals, and the Feedback by which the entire cybernetic system is regulated.

Personality researchers have long distinguished between personality traits and Character Adaptations (CAs), and several theorists⁴ have suggested that CAs are where a lot of personality change occurs. Various mechanisms have been proposed—e.g., changes in life narratives which influence our idea and expression of who we are, changes in micro-habits that compound into macro-level change—but the basic idea is that, even as our traits remain stable, the way that we express these traits can change. Some researchers (such as Jordan Peterson) even go so far as to suggest that CAs must change to ensure our success in a changing world.

I hinted at this idea of Character Readaptation in a previous essay on the cybernetics of Cognitive Behaviour Therapy. In essence, if we don’t adapt ourselves to fit the changing world around us, we start to encounter problems. Without change, the immature teenager won’t be taken seriously in the work place; the young man who’s always travelling for work will become an absent husband and father; the young woman who goes clubbing every night will become a neglectful wife and mother. By adapting our innate characteristics to our changing social context, we can maintain a coherent sense of self, while at the same time ‘becoming another person’ in the eyes of others.

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Conclusion

So can people change their personalities? I’d argue yes. While personality remains largely stable in the medium-term, there’s ample evidence to show that personality changes in the long-term (and not just as a consequence of biological maturity). Time will tell—but there have been some promising recent attempts to demonstrate intentional change, and I think the evidence is stacking up.

How to change one’s personality is a separate question. I’ll return to this topic in the future, once I’ve written more on the narrative elements of personality. But I’d love to know what you all think about this—can people truly change their personalities? And if so, how?

1. John et al., Handbook of Personality: Theory and Research, p. 16.

2. Shakespeare, As You Like It, act 2 scene 7.

3. To put it differently, we ‘adapt’ our inbuilt ‘characteristics’ to the environments in which we live.

4. Such as Colin DeYoung and Robert Krueger, who I've referenced previously, and Dan McAdams, whose work I'll be discussing in a future essay.