Eetu Marttila

Senior Researcher at the University of Turku

I currently work at the INVEST Research Flagship Centre in the CoROL project, studying inequality and institutional trust with register-linked survey data. Previously, in the FINSCI project, I studied trust in science and the role of emotions in political information processing.

I have a background in sociology but often work across disciplines. My research focuses broadly on political behavior and trust, wellbeing and loneliness, and social media use. My work is based on quantitative methods, including surveys, experiments, and register data.

Eetu Marttila
Email / Scholar / ORCID / CV

Featured Publication

Marttila, E., Koivula, A., Savolainen, I., Sirola, A., & Oksanen, A. (2026). The dynamic and reciprocal relationship between problematic internet use and loneliness: A longitudinal study. Media Psychology, 1-22. DOI

Problematic internet use (PIU) and loneliness are consistently linked, but whether one drives the other over time is unclear. Using six-wave panel data from 753 Finnish adults recruited through an online panel (4,518 observations), we examined how PIU and loneliness relate to each other within individuals. We used dynamic panel models that account for stable between-person differences and examine within-person changes, testing both contemporaneous (within-wave) and lagged (across-wave) associations over 6- and 12-month intervals. Results revealed strong reciprocal contemporaneous effects: when individuals experienced elevated PIU, they also reported greater loneliness, and vice versa. However, we found no evidence of lagged effects at either 6- or 12-month intervals. This suggests the relationship between PIU and loneliness unfolds within rather than across the specific measurement periods examined, though the contemporaneous effects may reflect unmeasured shorter-term dynamic processes occurring between waves.

All Publications

Peer-reviewed Articles

  • Mäki, O., Marttila, E., Häikiö, T., Pritup, D., Elovaara, K., Kivioja, P., & Kaakinen, J. K. (2026). Conspiracy Theory Endorsement Profiles: A Cluster Validation Study. European Journal of Social Psychology, 56(5), 861-872. DOI
  • Marttila, E., Koivula, A., Savolainen, I., Sirola, A., & Oksanen, A. (2026). The Dynamic and Reciprocal Relationship Between Problematic Internet Use and Loneliness: A Longitudinal Study. Media Psychology, 1-22. DOI
  • Marttila, E., & Koivula, A. (2024). Framing, emotions, and morality: Understanding media influence on moral attitudes towards the unvaccinated during COVID-19. The Social Science Journal, 62(2), 478-493. DOI
  • Koivula, A., Marttila, E., & Koiranen, I. (2024). Media framing and trust: A randomized survey experiment on attitudes towards the unvaccinated during the COVID-19 pandemic. Social Sciences & Humanities Open, 10, 101157. DOI
  • Koivula, A., Räsänen, P., Marttila, E., Sedgwick, D., & Hawdon, J. (2023). COVID-19 compliance and media consumption: A longitudinal study of Finland and the US during the first year of COVID-19. Journal of Broadcasting & Electronic Media, 67(4), 530-552. DOI
  • Marttila, E., Koivula, A., & Räsänen, P. (2021a). Cybercrime victimization and problematic social media use: Findings from a nationally representative panel study. American Journal of Criminal Justice, 46(6), 862-881. DOI
  • Marttila, E., Koivula, A., & Räsänen, P. (2021b). Does excessive social media use decrease subjective well-being? A longitudinal analysis of the relationship between problematic use, loneliness and life satisfaction. Telematics and Informatics, 59, 101556. DOI
  • Kemppainen, L., Koskinen, V., Bergroth, H., Marttila, E., & Kemppainen, T. (2021). Health and wellness–related travel: A scoping study of the literature in 2010-2018. SAGE Open, 11(2). DOI

Book Chapters

  • Koivula, A., Marttila, E., & Räsänen, P. (2024). Trust in experts according to media consumption and government satisfaction in the United States and Finland. In Perceptions of a Pandemic: A Cross-Continental Comparison of Citizen Perceptions, Attitudes, and Behaviors During Covid-19 (pp. 65-83). Emerald Publishing Limited.
  • Marttila, E. (2021). Yksinäisyys Suomessa koronaviruspandemian aikana. In A. Koivula, P. Räsänen, N. Salminen, E. Marttila, & I. Koiranen (Eds.), Digiajan ensimmäinen pandemia. Turun yliopisto.

Work in Progress

  • Marttila, E., Kaakinen, J. K., & Koivula, A. Social deprivation and trust in science: The moderating role of political distrust. (Under review)
  • Koivula, A., & Marttila, E. Media trust and political participation [Working title]. In F. Stiernstedt & P. Jakobsson (Eds.), Handbook on Media Trust. Edward Elgar. (Under review)
  • Marttila, E., & Kaakinen, J. K. Partisan affect amplifies the effect of party cues [Working title]. (In preparation)
  • Marttila, E., & Oksanen, A. Beyond "social media": Platform affordances, social psychological mechanisms and addiction. In I. Savolainen & E. Kauppila (Eds.), Research Handbook on the Social Psychology of Addiction. Edward Elgar. (In preparation)
  • Marttila, E., Koivula, A., & Kouvo, A. Education, cognitive resources and the structure of institutional trust [Working title]. (In preparation)