The world of personality psychology is familiar with the perennially hot topic of personality change. A recent article theorises a decline in conscientiousness, particularly among young adults. It also shows a decrease in agreeableness, extraversion, and emotional stability. So, can personality change? If so, is it changing right now?

On episode 132 of The Science of Personality, cohosts Ryne Sherman, PhD, and Blake Loepp discussed “The Troubling Decline in Conscientiousness” by John Burn-Murdoch, published in the Financial Times.¹

Burn-Murdoch’s article references a study of 15,000 to 20,000 US respondents that suggested personality seemed to be changing over time and with age. Specifically, the data were divided into three age groups: 16 to 39, 40 to 59, and 60 and older. Scores for conscientiousness on the five-factor model appeared to decline in all three age groups, with the steepest decline in the youngest age group.

But Ryne found this interpretation of the data to be unsatisfactory. “It’s contrary to what our data show at Hogan,” he said.

Why Is Conscientiousness Important?

The five-factor model’s personality characteristics are emotional stability (neuroticism), extraversion, openness to experience, agreeableness, and conscientiousness. But in personality psychology, there’s no consensus about what conscientiousness means. Different measures use different definitions. Broadly, conscientiousness refers to dedication, discipline, and hard work, as well as rule adherence, preference for structure, and detail orientation.

Why does conscientiousness matter? “Conscientiousness is correlated with all kinds of important outcomes. People who are more conscientious get better grades, have better job performance, and live longer,” Ryne said. Those outcomes do sound pretty important!

Yet high conscientiousness isn’t always beneficial. For innovation or entrepreneurism, people need to challenge rules, not follow them. As well, people with high conscientiousness tend to obey authority, as demonstrated in the Milgram experiments. Downsides exist for both high and low conscientiousness . . . so even if conscientiousness were declining in young people, the trend isn’t necessarily troubling.

Reasons for Personality Change

Measuring personality over time can be problematic, steeped in misinformation. What’s often overlooked in research on personality change is the variability in the sample. If researchers were to study large samples of personality assessment results from 2010 and 2020, the same people are not necessarily participating in both studies. In other words, the scores might vary because different people are involved.

In addition to that, there are three reasons personality scores might change. These are called age effects, time period effects, and generational effects.

• Age effects – As someone gets older, their personality may change. For instance, conscientiousness tends to gradually increase throughout a person’s life.
• Time period effects – The time period someone lives in can affect their personality; however, societywide time period effects on personality are relatively rare.
• Generational effects – Someone’s generation (also called birth cohort) can cause personality trends, such as children of the Great Depression growing into frugal adults.

Ryne said the analysis in the article didn’t take the three factors of personality change into account. Misinformation about these effects can cause someone to confound them, typically by perceiving a generational difference instead of correctly recognising an age difference.

Problems with Measuring Personality Change

Measuring just one of the three variables means that the other two can always be confused with each other. If we assess people who are 25 and people who are 50, we might seem to see age differences in their personality. But we could also be detecting differences between people born in 2000 and people born in 1975. To keep age constant, then, we would need to measure 25-year-olds in five-year increments beginning in 1975. But now both time and generation have become variable.

“Some would say separating these three things is statistically impossible to do,” Ryne said, although he added the age-period-cohort (APC) analysis could provide an empirical statistical solution to the problem. According to Ryne, the original data that informed the article didn’t apply the appropriate analysis to determine if the study’s outcomes were related to age, time period, or generational effects.

What Do Hogan Data Show About Personality Change?

At Hogan, we measure conscientiousness with the Hogan Personality Inventory (HPI) using a scale called Prudence. “I pulled data from more than 770,000 individuals from all over the world who had completed our assessments between 2015 and 2022,” Ryne said. “There are seven different decades of birth cohorts represented here, from the 1940s through the 2000s. When you analyse these data with the age-period-cohort analysis, you see very little difference at all over time.”

Has Prudence changed in seven decades? Not really. Ryne saw only one percentage point of fluctuation in Prudence due to age (from about 54 to 55). He saw time period effects as an expected result of the HPI measurement change in 2018. Finally, he saw a two-percentage-point difference due to birth cohort (from about 54 to 56). “That’s well within the realm of normal variation over time,” Ryne concluded. “There’s nothing that would cause any alarm for me.”

In sum, the analysis of our larger global data set doesn’t show any meaningful differences in personality change. “Personality doesn’t change that much,” Ryne said.

Listen to this conversation in full on episode 132 of The Science of Personality. Never miss an episode by following us anywhere you get podcasts.