Dr. Kathi Diel

Dr. Kathi Diel

Research Interests

Why do some people inspire us to work harder, while others make us want to give up? What emotions do we experience when we compare ourselves to others in everyday life? And how do these small, everyday experiences add up to shape our well-being and goal pursuit? I investigate how social comparisons influence motivation (pushing, coasting, and disengagement) and emotions relevant to goal pursuit (e.g., guilt, pride, and envy). Using experience sampling methods, I examine how momentary social comparison experiences influence these processes within individuals in everyday life, as well as how their cumulative effects shape goal attainment and well-being.

Another area of my research focuses on environmental psychology, in particular how social comparisons relate to climate action. Because environmental behavior is closely tied to morality, people tend to engage more strongly in downward rather than upward comparisons when they compare their environmental behavior to others, in order to maintain a positive moral self-image (Diel & Friese, 2024). I examine the consequences of this comparison tendency and how different types of comparisons may be used to foster more adaptive engagement in climate action.

Publications

Journal Articles

Diel, K., van der Spiegel, G., Hofmann, W., Wisniewski, D., Grelle, S., Escher, Y. A., Petrowsky, H. M., & Genschow, O. (in press). Are free will believers happier? Converging evidence from daily life and experimental research. Social Psychological and Personality Science. 

Weber, M.*, Friese, M.*, Escher, Y. A., Petrowsky, H. M., Boecker, L., Diel, K., Muniak, P., Neumann, M., Oomen, D., Strauch, A., Genschow, O.**, & Loschelder, D. D.** (in press). A kick to desire: National teams’ performance during the UEFA EURO 2024 affected the frequency with which Europeans experienced sexual events. Social Psychological and Personality Science.

Petrowsky*, H. M., Escher*, Y. A., Boecker, L., Diel, K., Muniak., P., Neumann, M., Oomen, D., Schwarz, L., Strauch, A., Weber, M., Friese, M.**, Genschow, O.**, & Loschelder, D. D.** (2026). Longitudinal event-sampling dataset of football fans across five countries during the 2024 European championship. Scientific Data,13, 935. https://doi.org/10.1038/s41597-026-07643-z  

Ecker, Y., Diel, K., Hofmann, W., Unkelbach, C., Imhoff, R. (in press). The Role of Comparison Processes in Maintenance Goals: Evidence from the Health and Relationship Domains. Applied Psychology: Health and Well-Being.

Diel, K.*, Boecker, L.*, Lange, J., Hofmann, W., & Crusius, J. (2026). Emotional Dynamics of Social Comparisons: Nonlinear Relationships Between Comparison Extremity and Social Emotions, and Their Motivational Functioning. Personality and Social Psychology Bulletin. https://doi.org/10.1177/01461672251333249

Diel, K., Hofmann, W., Grelle, S., Boecker, L., & Friese, M. (2025). Prepare to compare: Effects of an intervention involving upward and downward social comparisons on goal pursuit in daily life. Personality and Social Psychology Bulletin. https://doi.org/10.1177/01461672231219

Diel, K., & Friese, M. (2024). Morally charged: Why people prefer to compare themselves with others who are less environmentally friendly than themselves. Journal of Environmental Psychology. https://doi.org/10.1016/j.jenvp.2024.102318

Vlasceanu, M., Doell, K. C., Bak-Coleman, J. B., Todorova, B., Berkebile-Weinberg, M. M., Grayson, S. J.,.... Diel, K.,… & Lutz, A. E. (2024). Addressing climate change with behavioral science: A global intervention tournament in 63 countries. Science Advances, 10(6), eadj5778. 
http://doi.org/10.1126/sciadv.adj5778

Doell, K. C., Todorova, B., Vlasceanu, M., Bak-Coleman, J. B., Pronizius, E., Schumann, P., ... Diel, K.....,& Lutz, A. E. (2024). The International Climate Psychology Collaboration: Climate change-related data collected from 63 countries. Scientific Data, 11(1), 1066. https://doi.org/10.1038/s41597-024-03865-1

Unkelbach, C., Alves, H., Baldwin, M., Crusius, J., Diel, K., Galinsky, A. D., Gast, A., Hofmann, W., Imhoff, R., Genschow, O., Lammers, J., Pauels, E., Schneider, I. K., Topolinski, S., Westfal, M., & Mussweiler, T. (2023). Relativity in social cognition: Basic processes and novel applications of social comparisons. European Review of Social Psychology. https://doi.org/10.1080/10463283.2022.2161043

Diel, K.*, Broeker, L.*, Raab, M., & Hofmann, W. (2021). Motivational and emotional effects of social comparison in Sports. Psychology of Sport and Exercise, 57, 102048. https://doi.org/10.1016/j.psychsport.2021.102048

Diel, K., Grelle, S., & Hofmann, W. (2021). A motivational Framework of social comparison. Journal of Personality and Social Psychology, 120(6), 1415-1430. https://doi.org/10.1037/pspa0000204

Fleischmann, A., Lammers, J., Diel, K., Hofmann, W., & Galinsky, A. D. (2021). More threatening and more diagnostic: How moral comparisons differ from social comparisons. Journal of Personality and Social Psychology. https://doi.org/10.1037/pspi0000361

Vohs, K. D., Schmeichel, B. J., Lohmann, S., Gronau, Q. F., Finley, A. J., Ainsworth, S. E.,... Diel, K...., & Albarrac´ın, D. (2021). A multisite preregistered paradigmatic test of the ego-depletion effect. Psychological Science, 32(10), 1566-1581. https://doi.org/10.1177/0956797621989733

Rom, S.C., Katzir, M., Diel, K., & Hofmann, W. (2019). On trading off labor and leisure: a process model of perceived autonomy and opportunity costs. Motivation Science. https://doi.org/10.1037/mot0000148

Diel, K., & Hofmann, W. (2019). Inspired to perspire: The predicted interplay of social comparison direction and standard extremity in the context of challenging exercising goals. Social Cognition, 37, 247-265. https://doi.org/10.1521/soco.2019.37.3.247

Dohle, S., Diel, K., & Hofmann, W. (2018). Executive functions and the self-regulation of eating behavior: A review. Appetite, 124, 4-9. https://doi.org/10.1016/j.appet.2017.05.041

Book Chapter

Hofmann, W., Dohle, S., & Diel, K. (2020). Changing behavior using integrative self-control theory. In: M. S. Hagger, L. D. Cameron, K. Hamilton, N. Hankonen, & T. Lintunen (Eds.), The handbook of behavior change (pp. 150 - 163). Cambridge: Cambridge University Press.

Hofmann, W., Diel, K., & Seibel, M. (2018). Foods, sex, and drugs: Appetitive desires and subjective well-being. In E. Diener & S. Oishi (Eds.), Handbook of well-being. Salt Lake City, UT: DEF Publishers.

*shared first authorship
**shared senior authorship

Media Coverage (Selection)

June, 2026 | The Times 

Why believing in free will could be the secret to happiness  | Article covering a publication in SPPS

November, 2025 | Saarländischer Rundfunk (Aktueller Bericht) 

Filterblasen und Meinungsbildung auf Social Media (Filter bubbles and opinion formation on social media) | Interview (from minute 11:22).

November, 2025 | Saarländischer Rundfunk

Botox-Boom auf Social Media (Botox boom on social media | Article based on an interview

April, 2025 | Tagesspiegel

Alle sind schöner, fitter, reicher als ich. Kann man sich vergleichen ohne sich selbst zu schaden (Everyone is more attractive, fitter, and richer than I am. Can we compare ourselves to others without harming ourselves?) | Article based on an interview

Januar, 2025 | Tagesspiegel

Der Reichenreport: Bin ich noch Mittelschicht oder schon vermögend? (The Wealth Report: Am I still middle class or already wealthy?) | Article based on an interview

December, 2024 | ZDF Terra Xplore 

Reichtum, wie viel Geld ist dir genug? mit  Dr. Leon Windscheid (Wealth: How much money is enough?)  | TV episode