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In the Jyväskylä Longitudinal Study of Personality and Social Development (JYLS), the development of the same individuals (born in 1959) has been so far followed from age 8 to 61. The latest data collection (2020–2021) was part of the ‘TRAILS’ (Developmental Psychological Perspectives on Transitions at Age 60: Individuals Navigating Across the Lifespan) project led by research director Katja Kokko and funded by the Academy of Finland.

In the latest data collection phase, data were collected using a psychological interview and self-report inventories. Additionally, a medical examination with blood samples, as well as physical activity monitoring were conducted. In this latest phase, the main aim was to explore how retirement or its anticipation, grandparenthood, leisure-time activities and an increased concern over health—in interaction with personality characteristics—link to mental well-being.

Similar to earlier data collection phases, information is gathered, among others, about well-being, personality, work and education, family, leisure time activities, social network, and health and health behaviors. In childhood (at age 8) and adolescence (at age 14) the socioemotional behavior of the participants was assessed by teachers and peers. Data about the childhood school achievement and upbringing environment are also available.

The JYLS data have been used in hundreds of national and international scientific publications, including both journals and books. The JYLS data have been used in 21 doctoral dissertations and dozens of master’s theses. The research themes have been related, for example, to the following: 1) socioemotional behavior and personality from childhood to adulthood, 2) the formation of education and working career, 3) family of origin and one’s own family, 4) health and health behaviors, 5) social adjustment and delinquency, 6) the development of well-being, and 7) mid-life development.

The ongoing JYLS study was initiated at the University of Jyväskylä by Lea Pulkkinen in 1968 who led the study until the end of 2012. Since the beginning of 2013, the JYLS has been led by Research Director Katja Kokko.


The main funder of the JYLS has been the Academy of Finland (1974, 1979, 1986-2013, 2019-2023). The ongoing TRAILS data collection is funded through the Academy of Finland research grant (2019–2023, grant number 323541).

Further information about the study, Principal Investigator, Research Director Katja Kokko, Gerontology Research Center and Faculty of Sport and Health Sciences, University of Jyväskylä.

Selected recent publications

Fadjukoff, P., Feldt, T., Kokko, K., & Pulkkinen, L. (2019). Identity status change within personal style clusters: A longitudinal perspective from early adulthood to midlife. Identity: An International Journal of Theory and Research, 19, 1–17. doi:10.1080/15283488.2019.1566066

Karvonen, J., Törmäkangas, T., Pulkkinen, L., & Kokko, K. (2019). Associations of temperament and personality traits with frequency of physical activity in adulthood. Journal of Research in Personality. doi: 10.1016/j.jrp.2019.103887

Kekäläinen, T., Freund, A. M., Sipilä, S., & Kokko, K. (2020). Cross-sectional and longitudinal associations between leisure time physical activity, mental well-being and subjective health in middle adulthood. Applied Research in Quality of Life, 15, 1099–1116. doi: 10.1007/s11482-019-09721-4

Kekäläinen, T., Karvonen, J., Törmäkangas, T., Pulkkinen, L., & Kokko, K. (2022). Pathways from childhood socioemotional characteristics and cognitive skills to midlife health behaviors. Psychology & Health. doi: 10.1080/08870446.2022.2041639

Kekäläinen, T., Sipilä, S., Saajanaho, M., & Kokko, K. (2021). The role of personality traits in leisure time physical activity during the COVID-19 pandemic. Personality and Individual Differences. doi: 10.1016/j.paid.2021.111080

Kokko, K., & Feldt, T. (2018). Longitudinal profiles of mental well-being as correlates of successful aging in middle age. International Journal of Behavioral Development, 42, 485–495. doi: 10.1177/0165025417739177

Pulkkinen, L. (2017). Human development from middle childhood to middle adulthood: Growing up to be middle-aged. (Yhteistyössä Katja Kokon kanssa.) London: Routledge.

Reinilä, E., Kekäläinen, T., Saajanaho, M., & Kokko, K. (2023). The structure of mental well-being and its relationship with generativity in middle adulthood and the beginning of late adulthood. International Journal of Behavioral Development. doi: 10.1177/01650254231165837

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