Yes, Your Personality Could Change as You Get Older

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So there I was at my 30th high school reunion at a restaurant in northern New Jersey a few years ago. I had attended a relatively small high school and pretty much knew just about everyone.

Several people at the event came up to me saying that they were surprised by certain life outcomes of mine. I ended up being a reasonably successful academic and published author whose work has made it broadly into the mainstream. I don't think a single classmate of mine from high school would have seen that coming. In fact, I don't think that 18-year-old Glenn saw that coming either.

You see, in high school, I was a very ho-hum student who cared little about academics. Not a single teacher would have called me conscientious by any stretch of the imagination. And while I was not exactly a wallflower, I was reasonably quiet and I'd say generally introverted. I had a small group of friends and often kept to myself.

Adulting

As I developed into adulthood, I ramped up my conscientiousness and ended up acing the psychology Ph.D. program at the University of New Hampshire. My level of extraversion has pretty much only increased since I was 18 years old. By this point, I've given dozens (if not hundreds) of presentations on all kinds of topics to all kinds of audiences all around the world. And I find that I never get an ounce of jitters before I present.

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This said, in many ways, I'm still the same person I was during my upbringing. I have a pretty strong silly streak that I just can't seem to shake. I absolutely love making music and engaging in other creative endeavors.

And I still find myself lost in thought at times, extensively pondering what may well seem like idiosyncratic questions (such as how yucca plants, famous for growing in desert environments, flourish on our property in upstate New York).

Does Personality Change Across the Lifespan?

A timeless question in the field of psychology is this: Are people capable of true personality change across the lifespan? This question is, in fact, one of these hotly debated questions with some very solid researchers providing strong evidence for each side of this debate (see a summary of this debate in my book Own Your Psychology Major!).

Based on an extensive body of research on this question, the answer essentially is this: To some extent.

Based on decades of research into human personality, behavioral scientists have found that nearly all traits seem to map onto one of five broad-based, over-arching traits that characterize human personality (see Costa et al., 2019). These traits include:

• extraversion (how outgoing and sociable one is)
• emotional stability (how prone toward emotional stability versus volatility one is)
• conscientiousness (how diligent versus disorganized one is)
• open-mindedness (how open to new ideas and experiences one is)
• agreeableness (how much one tends to go with the flow in social situations)

To address the question of how stable traits are across the lifespan, in a thorough review paper, trait psychologists Costa, McCrae, and Löckenhoff (2019) reviewed various studies using samples that varied in terms of the cultures of samples studied, the ages of samples studied, methodologies, and more.

While their paper addresses a broad range of factors, perhaps the simplest way to boil down the bottom line of their work is found in a summary of two studies conducted by Chopik and Kitayama (2017).

In Costa et al.'s summary of these studies, they write the following:

Consider two examples. Chopik and Kitayama (2017) examined data from 3,850 U.S. participants initially aged 25 to 75 and retested after 9 years. They assessed personality with 25 adjectives, five for each of the five personality factors. The observed retest correlations were 0.64, 0.70, 0.69, 0.64, and 0.61... Chopik and Kitayama also analyzed data from 649 Japanese participants initially aged 30 to 79... the observed retest correlations in the Japanese sample—0.66, 0.74, 0.70, 0.64, and 0.63...—showed a high level of stability.... The median retest for U.S. participants was 0.64; for Japanese participants, it was 0.66.

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Let me break these ideas down for a lay audience. There are a few things to note. First off, the fact that the median retest correlations for U.S. and Japanese participants were nearly identical speaks to how ubiquitous the Big Five personality traits are across diverse cultures.

Further, from a statistical standpoint, let's dissect what the test-retest correlation of about .65 (the average of the two median coefficients from above) means. First off, a correlation of .65 is a positive correlation. That simply means that low scores on one variable tend to go with low scores on another variable, while high scores on one variable tend to go with high scores on the other variable.

So across all of the Big 5 traits, how people scored at Time 1 tended to, on average, be pretty similar to how they scored on those same traits years later. So on one hand, these findings speak to stability in personality traits across life.

This said, let's analyze these findings in a more granular fashion. In statistics, we can square a correlation coefficient to come up with an index of how much that coefficient explains the relationship between two variables. So if you have a correlation between two variables of .90, for instance, that means that .81, or 81 percent of the scores on one variable are explained by scores on the other variable.

R Squared

This statistic, which we often refer to as r² (r squared), pretty much tells us how much variability in the second variable is accounted for by scores in the first variable.

That said, let's think about how this concept of r² relates to the findings that are summarized by Costa et al. (2019). If correlations among Big 5 variables tend to be in the .65 range (when examining scores on the same traits for the same participants at two different times in life), that means that r² is about .42.

Here's how to interpret an r² of .42. If r² is .42, that means that about 42 percent of scores at Time 2 on some trait variable (e.g., how someone scored on extraversion) are explained by scores at Time 1 on that same variable.

So slightly less than half of how extraverted (or emotionally stable or open-minded, etc.) one is at one point in life seems to be predicted by how that person would have scored on that same variable several years prior.

What is interesting about an r² in this range is this: If 42 percent of how one scored at time 2 on some trait is accounted for by how that person scored on that same trait years prior, then 58 percent of how that person scored at Time 2 is accounted for by other factors. This is a critical point.

A higher proportion of our personality at any given time of life is predicted by factors beyond one's personality as observed in the past. In short, not only can people change—people do change. And change is, in some ways, more the rule than the exception.

Bottom Line

So often in life, we find ourselves wondering about personality stability. A parent of an extremely shy child might worry that this child is doomed to a life of social isolation. A parent of an emotionally volatile teen may worry that their kid is going to grow up to be a wild one. Someone who failed in a relationship due to being too emotionally volatile may worry that this trait is going to destroy future relationships.

That said, the research on personality stability across the lifespan tells two critical tales—both of which need to be considered carefully.

On one hand, scores on basic personality traits tend to be positively correlated at different points in life. So how you are at one point in life is significantly and positively predictive of how you are likely to be at a later point in life. That said, personality change seems to actually be a very substantial phenomenon that has been documented across age groups and cultures.

Is personality change possible across the lifespan? You bet. As I see it, in many ways, this fact provides all kinds of reasons for hope as people navigate the often complex and treacherous waters of life.

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