Beyond Age and Generations: How Considering Period Effects Reshapes Our Understanding of Personality Change
Year: 2025
Type: preprint
Study design: Observational Study
Abstract: Age, cohort, and period effects are three ways to explain personality trait change over time. While past research mostly focused on age differences, showing relatively consistent patterns, evidence for cohort differences is more mixed, and period differences have hardly been examined. However, age, period, and cohort are exactly collinear (age = period – cohort), such that estimates are likely confounded and always hinge on so-called identification assumptions. Identification assumptions shape substantive conclusions, and inappropriate or inconsistent strategies may explain past discrepant findings. To address this age-period-cohort identification problem in personality change, we leveraged four large-scale (Ntotal >2 Mio) repeated cross-sectional datasets from 2003–2022. Our aims were to demonstrate how identification assumptions common in personality studies impact estimates for age, cohort, and period; and to use weaker, substantively informed assumptions to narrow down the range of plausible solutions. Results showed that common identification strategies of constraining one temporal effect to zero can dramatically affect conclusions—less for age-graded, but more for generational differences. Using weaker assumptions, our results indicated that all three factors—age, cohort, period—likely contribute to trait differences over time. Assuming age-graded change in a certain direction revealed cohort-related decreases in extraversion, openness, and neuroticism and increases in agreeableness; alongside period-related increases in extraversion, openness, and conscientiousness. This suggests that several previously assumed cohort differences may actually be driven by period effects, overlooked due to strong identification assumptions. Overall, highlighting the importance of appropriate identification strategies, our results offer unique insights into factors driving trait change over time.
Language: English
Subfield: Clinical Psychology
Field: Psychology
Domain: Social Sciences
Open Access status: green
Awards: Social Sciences & Humanities Open Cloud, Multinational Advancement of Research Infrastructures on Ageing, G1178032220, G1237079599, G1330667123, G1397107050, G1428006373, G1450655456, G1565542540, G1608581485, G1708035608, G1750703574, G1756054413, G1778268290, G1781191216, G1820526844, G2077389594, G2343781458, G24207250, G2465118858, G2496819784, G2576676356, G2593358879, G2841052746, G2881429984, G3166864496, G323020161, Achieving world-class standards in all SHARE countries, G3361099077, G3440788226, G3457581384, G3497955178, G3654244103, G3687180791, HEALTH AND ECONOMIC STATUS IN OLDER POPULATIONS, G4096536797, G4105375558, G4165969582, RAND Center for the Study of Aging, G4290142911, G434337789, Upgrading the Survey of Health, Ageing and Retirement in Europe – preparatory phase, G4545110052, G4569152855, G4587185496, Cohesion in further developing and innovating SHARE across all 28 member countries, G4723430573, G4847675667, SFB 884: Politische Ökonomie von Reformen, G5021238699, G503278667, G504669776, G5062201959, Data Service Infrastructure for the Social Sciences and Humanities, G5207492846, Die Vorhersagekraft beruflicher Interessen: Eine multiperspektivische Untersuchung, G5618942462, Non-intended health, economic and social effects of the COVID-19 epidemic control decisions: Lessons from SHARE (SHARE-COVID19), G5857780965, G6053673296, G6055688980, G6122222817, G6476390097, G6678519423, G6767647029, G6969501727, G6978085111, Synergies for Europe's Research Infrastructures in the Social Sciences, G751768989, DEVELOPING AN ISRAELI VERSION OF THE HRS/SHARE PROJECT, G8072554765, G8677177991, Longitudinal Enhancement and Access imProvement of the SHARE infrastructure, G8806983220, G8875743412, G8957671751, G9000113159, Understanding and Improving Healthcare Decision-Making and Outcomes for People Living with Alzheimer's Disease and Related Dementias, Health and Retirement Study: Yrs 35-40, G93458789
OpenAlex ID: W4409915244