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It’s fairly clear that an individual’s personality changes throughout the course of their lifetime, but most of the studies demonstrating that change only account for certain ages. Previous studies that have been really successful in looking at personality change over the lifespan failed to obtain significant amounts of old-aged adults as part of their samples (e.g., Lucas & Donnellan, 2011; Roberts & Delvecchio, 2000). Researchers Kandler, Kornadt, Hagemeyer, and Neyer decided to try and fill the informational age gap. Their work attempted to answer some of the underlying psychological questions that explain phenomena everyone witnesses, such as “Why does Grandma hate everything from the 21st century?” In their longitudinal study of twin pairs aged 64 to 89, Kandler and his colleagues found that contrary to what previous studies might suggest due to their lack of age-range, adults in later life still experience significant personality change.
Although theories of personality traits aren’t universally agreed upon, most agree on the idea of a finite number of trait dimensions. In this study, arguably the most validated theory was used to assess personality—the Big Five personality traits. In addition to these five (Extraversion, Openness to Experience, Agreeableness, Neuroticism, and Conscientiousness) the researchers assessed perceived control and affect intensity (emotional reactivity). They were also interested in seeing if psychological well-being played a role in personality change, so they assessed well-being as a state. These measures were assessed twice, with a five-year gap in between assessments. The study could have been more informational and beneficial if the gap were longer, but given the age of the participants, the researchers stretched as far as they could while still maintaining most of their original group. The male and female identical and fraternal twins were tested using self-assessment tests.
In order to see patterns of continuity and change in personalities, mean-level change and rank-order change were analyzed. Mean-level change shows if the typical individual increases, decreases, or stays the same on any particular trait over time. Kandler et al. found that, contrary to previous studies, mean-level change drifted in the opposite direction from younger-adults. For example, past meta-analyses showed that as individuals age, their neuroticism decreases (Roberts, Walton, & Viechtbauer, 2006). Whereas the present study showed that in old-age, neuroticism begins to increase again. This is partially explained by the extra concern older adults have to place on daily health-risks. One of the more interesting discoveries from the study was the finding that well-being and affect intensity remained mostly constant over time. Perhaps this is due to a balance of emotional gains and losses in later life? Does the emotional maturity that allows one to handle loss well even out with the increase in losses one experiences in older age? More in-depth analysis of this trend would be highly interesting.
Rank-order change describes if individuals maintain the same ordering on their traits over time. While the use of twins did not play much of a role in the results found (other than reducing error to some extent), it did have an interesting implication in looking at plasticity in old age. It was found that individual differences were largely stable between the two assessment times, leading the researchers to suggest that perhaps changes in rank-order, when they do occur, are due to environmental influences rather than the more universal genetic influences. Environmental factors that were not shared by the twins were much more significant sources of individual difference in personality change
This study had many main objectives, with over 6 hypotheses being tested, but not all of them gave as successful a result. Unfortunately, this research was rather unsuccessful in determining anything about the relationship between well-being and personality change other than there is no reciprocity of their effects on one-another. However as a whole, Kandler and his colleagues added much meaningful data to the area of personality research. The findings from this research seem to agree with the lifespan theory of trait development (introduced by Roberts and colleagues) in that changes in personality happen throughout major life transitions, and that these changes can keep happening throughout life. More widespread application of these methods, even amongst younger participants, could even better explain changes in personality, and where they are coming from.
Kandler, C., Kornadt, A. E., Hagemeyer, B., & Neyer, F. J. (2015). Patterns and sources of personality development in old age. Journal of Personality and Social Psychology, 109(1), 175-191. doi:10.1037/pspp0000028
Lucas, R. E., & Donnellan, M. B. (2011). Personality development across the life span: Longitudinal analyses with a national sample from Germany. Journal of Personality and Social Psychology, 101, 847–861.http://dx.doi.org/10.1037/a0024298
Roberts, B. W., & Delvecchio, W. F. (2000). The rank-order consistency of personality traits from childhood to old age: A quantitative review of longitudinal studies. Psychological Bulletin, 126, 3–25. http://dx.doi .org/10.1037/0033-2909.126.1.3
Roberts, B. W., Walton, K. E., & Viechtbauer, W. (2006). Patterns of mean-level change in personality traits across the life course: A meta- analysis of longitudinal studies. Psychological Bulletin, 132, 1–25.http://dx.doi.org/10.1037/0033-2909.132.1.1