Wojtek Przepiorka


Research agendas

Below are brief descriptions of my long-term research agendas. Although I work on a broad and expanding range of topics, most of my publications can be subsumed under these general terms. Please consult the Publications section for a complete list of my publications.

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The big bang of my scientific universe was the realization how as simple a mechanism as reputation formation could promote cooperation among strangers in online markets at a large scale. So-called reputation systems have promoted mutually beneficial economic exchange throughout history, and continue to do so today in legal and illegal online markets. By leaving information feedback after completed exchanges, people voluntarily contribute to the collective good that reputation systems constitute. People’s motives for sharing information about their experiences with trading partners, products and services, are diverse and manifest via different channels. Without feedback, online markets would lose their effectiveness to screen untrustworthy traders and low-quality products. Reputation formation as a mechanism for reducing uncertainty in social and economic exchange is a special manifestation of a general theoretical framework subsumed under signaling theory.

Key publications
Diekmann, A., & Przepiorka, W. (2019). Trust and Reputation in Markets. In F. Giardini & R. Wittek (Eds.), The Oxford Handbook of Gossip and Reputation (pp. 383-400). Oxford: Oxford University Press.
Przepiorka, W. (2013). Buyers pay for and sellers invest in a good reputation: More evidence from eBay. Journal of Socio-Economics, 42(C), 31-42.
Przepiorka, W., Norbutas, L., & Corten, R. (2017). Order without law: Reputation promotes cooperation in a cryptomarket for illegal drugs. European Sociological Review, 33(6), 752-764.

Andreas Diekmann is the one to blame for my lack of disciplinary focus. I like to think though that understanding and speaking the languages of different disciplines is an essential precondition for the study of human cooperation. My urge to look over the rim of a tea cup allowed me to see signaling theory as a cross-disciplinary framework that could explain phenomena related to human cooperation. These are, for example, altruism and generosity, peer-punishment, conflict and deterrence, reputation formation, and group norms. Communication is essential for the evolution of a cooperative species but in itself has to be established and maintained. In line with signaling theory, certain types of behaviors will be more indicative of individuals’ unobservable traits and intentions than other types of behaviors. This in turn helps reduce uncertainties in human social interactions. However, unlike what biological determinism would suggest, the meanings of such behaviors (i.e. signals) are frequently re-negotiated as part of the normative systems of human groups and societies.

Key publications
Przepiorka, W., & Berger, J. (2017). Signaling theory evolving: Signals and signs of trustworthiness in social exchange. In B. Jann & W. Przepiorka (Eds.), Social dilemmas, institutions and the evolution of cooperation (pp. 373-392). Berlin: De Gruyter Oldenbourg.
Przepiorka, W., & Diekmann, A. (2021). Parochial cooperation and the emergence of signalling norms. Philosophical Transactions of the Royal Society B, 376, 20200294.

Growing up as a first-generation migrant teaches one lessens about social norms. Exploring the social world by means of testing normative boundaries using (field) experiments has thus come naturally to me. I have learned that the enforcement of social norms through peer-sanctioning (both negative and positive) is essential for maintaining trust, cooperation and cohesion in society. However, people apply double standards between members of different groups when enforcing norms. It can also happen that norm breakers are not sanctioned because bystanders are unable to agree on who should sanction the norm breaker. And, sometimes, for better or for worse, norm breakers instigate more norm-breaking behavior by others. How these mechanisms come together to bring about and change social norms is a most fascinating question. We seem to understand that norms coevolve with people’s needs to cooperate, coordinate and trust each other.

Key publications
Diekmann, A., Przepiorka, W., & Rauhut, H. (2015). Lifting the veil of ignorance: An experiment on the contagiousness of norm violations. Rationality and Society, 27(3), 309-333.
Horne, C., & Przepiorka, W. (2021). Technology use and norm change in online privacy: Experimental evidence from vignette studies. Information, Communication & Society, 24(9), 1212-1228.
Przepiorka, W., & Diekmann, A. (2013). Individual heterogeneity and costly punishment: a volunteer's dilemma. Proceedings of the Royal Society B, 280(1759), 20130247.
Przepiorka, W., & Berger, J. (2016). The sanctioning dilemma: A quasi-experiment on social norm enforcement in the train. European Sociological Review, 32(3), 439-451.
Przepiorka, W., Szekely, A., Andrighetto, G., Diekmann, A., & Tummolini, L. (2022). How Norms Emerge from Conventions (and Change). Socius, 8, 1-16.

The late economist and Nobel laureate Kenneth Arrow described trust as “an important lubricant of a social system” and therein condensed the most important features of trust. If people can trust each other, rely on each other’s promises and agreeing on expectations about the course of action, such reliance can save valuable resources (e.g., time and money spent for monitoring and setting up of legal contracts). Although seeing trust as a lubricant is essential for understanding its consequences, the metaphor is less informative of the causes of trust. Why do people, even strangers, trust each other? Why are some people more trusting then others? And why is it that in some countries people exhibit higher levels of trust than in others? The first step towards addressing these questions is to recognize that people’s expectations of others’ trustworthiness are the precursors of these people’s trust in others. To address the question where these expectations come from and how they can be managed constitutes the bulk of my research on trust.

Key publications
Lo Iacono, S., Przepiorka, W., Buskens, V., Corten, R., & van de Rijt, A. (2021). COVID-19 vulnerability and perceived norm violations predict loss of social trust: A pre-post study. Social Science & Medicine, 291, 114513.

Being able to speak out in public, be recognized and accepted as a member of the majority is not something native majority members naturally learn to appreciate but take pause if one tries. While incumbents can claim normative sovereignty, newcomers need to make an effort to blend in and earn incumbent status. Sometimes this is not desired. Luckily, some incumbent groups seem to be willing and patient enough for newcomers to adjust their normative views and expectations, and some are even willing to revise their own. If successful, integration can increase intergroup cooperation, spur innovation and moderate the negative consequences of aging societies. Yet, suddenly emerging conflicts can tear the veils of equality, accentuate differences and lead to social closure. How groups and their individual members navigate openness and closure is maybe the most generative of sociological questions.

Key publications
Macanovic, A., Tsvetkova, M., Przepiorka, W., & Buskens, V. (2024). Signals of belonging: Emergence of signalling norms as facilitators of trust and parochial cooperation. Philosophical Transactions of the Royal Society B, 379, 20230029.
Otten, K., Buskens, V., Przepiorka, W., & Ellemers, N. (2020). Heterogeneous groups cooperate in public good problems despite normative disagreements about individual contribution levels. Scientific Reports, 10, 16702.
Otten, K., Frey, U. J., Buskens, V., Przepiorka, W., & Ellemers, N. (2022). Human cooperation in changing groups in a large-scale public goods game. Nature Communications, 13, 6399.

Maintaining human cooperation locally and globally is an everlasting challenge. It seems difficult to aid the historically unfortunate without making the fortunate conscious of the secondariness of their histories – both retrospectively and prospectively. But are we doomed to embrace global Maoism or perish (shortly)? My conception of my academic self is to work towards answering this question with a no. Demonstrating how and why institutions can have a lasting effect on cooperation in and between societies has thus been a leading theme throughout my academic career. Then, I believe, enabling people to exercise choice over institutions is the best we can do.

Key publications
Lo Iacono, S., Przepiorka, W., Buskens, V., Corten, R., van Assen, M., & van de Rijt, A. (2023). The competitive advantage of sanctioning institutions revisited: a multi-lab replication. PNAS Nexus, 2(5), pgad091.

Last but not least, when ideas get out of hand, my research calls for novel applications of quantitative research methods. How do we measure moral norms in individuals from short texts these individuals wrote? How do we assess the impact of features of online markets on individual market action and outcomes if extensive market-level data is difficult to come by? How do we establish the prevalence of the correlation between generosity and trustworthiness if it is safe to assume that no one would admit to be short of either? How do we assess the quality of digital behavioral data without having access to the data? Although the papers listed below (and above) could not always fully answer the questions they set out to address, they died trying.

Key publications
Jiao, R., Przepiorka, W., & Buskens, V. (2021). Reputation effects in peer-to-peer online markets: A meta-analysis. Social Science Research, 95, 102522.
Jiao, R., Przepiorka, W., & Buskens, V. (2022). Moderators of reputation effects in peer-to-peer online markets: a meta-analytic model selection approach. Journal of Computational Social Science, 5, 1041-1067.
Przepiorka, W. (2023). Laboratory experiments. In U. Liebe (Ed.), Handbook of Quantitative Methods in Sociology, (pp. forthcoming). Cheltenham: Edward Elgar.
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