Many studies suggest that our personalities remain fairly stable, even over the course of decades. Yet a small but long-running study finds that traits related to dependability differ substantially between adolescence and late life. The findings raise new questions and highlight the challenges inherent in trying to track a person's defining characteristics over many years.

In the new research, published in December 2016 in Psychology and Aging, researchers in the U.K. reached out to a group of 635 77-year-olds from Scotland who had taken part in a study when they were 14. Back then, their teachers had rated them on six personality characteristics related to dependability: self-confidence, perseverance, mood stability, conscientiousness, originality and desire to excel. Some 60 years later a total of 174 participants from the original cohort rated themselves on the same six traits and had a close friend or relative rate them as well.

Lead author Ian Deary, a psychologist at the University of Edinburgh, expected, based on earlier findings, that dependability scores might remain stable over time. In fact, he and his colleagues found no relation between ratings for dependability-related traits over the 63-year span studied. (Deary emphasizes that his findings apply only to these six traits—not overall personality.)

One of the study's strengths is that it covers such a long period, but this characteristic also makes the research challenging. Nate Hudson, a social psychologist at Michigan State University who was not involved in the study, points out that the lack of personality stability could be an artifact of having different people rate the participants. Ideally, the same person would rate a subject's personality at both time points when assessments were made.

In decades-spanning studies, many subjects go missing, die or choose not to participate in follow-up assessments. Deary and his colleagues enrolled only 174 of the original participants, a number that makes it tough to find subtle, but real, correlations in sets of data. “It is difficult to know from their study alone whether there is truly zero stability in personality from age 14 to 77,” Hudson says. Deary's work moves the field forward—but more research is needed to get a full picture of how personality evolves throughout a lifetime.