I am a researcher in the fields of behavioral and experimental economics at the University of Cologne, where I examine issues of paternalism and support for policy through experiments and surveys. Additionally, I develop software tools that help expand the methodological approaches in economic research. In July 2025, I will join the University of Melbourne as a tenure-track Lecturer to continue my work as a researcher and lab manager.

Selected work-in-progress

• Knowledge and Freedom: Evidence on the Relationship Between Information and Paternalism

  Working paper · Replication package · Abstract [−] Abstract [+]

  When is autonomy granted to a decision-maker based on their knowledge, and if no autonomy is granted, what form will the intervention take? A parsimonious theoretical framework shows how policymakers can exploit decision-maker mistakes and use them as a justification for intervention. In two experiments, policymakers (“Choice Architects”) can intervene in a choice faced by a decision-maker. We vary the amount of knowledge decision-makers possess about the choice. Full decision-maker knowledge causes more than a 60\% reduction in intervention rates. Beliefs have a small, robust correlation with interventions on the intensive margin. Choice Architects disproportionately prefer to have decision-makers make informed decisions. Interveners are less likely to provide information. As theory predicts, the same applies to Choice Architects who believe that decision-maker mistakes align with their own preference. When Choice Architects are informed about the decision-maker’s preference, this information is used to determine the imposed option. However, Choice Architects employ their own preference to a similar extent. A riskless option is causally more likely to be imposed, being correlated with but conceptually distinct from Choice Architects' own preference. This is a qualification to what has been termed “projective paternalism.”

• Paternalism and Deliberation: An Experiment on Making Formal Rules

  Working paper · Preregistration · Replication package · Abstract [−] Abstract [+]

  This paper studies the relationship between soft and hard paternalism by examining two kinds of restriction: a waiting period and a hard limit (cap) on risk-seeking behavior. Mandatory waiting periods have been instituted for medical procedures, gun purchases and other high-stakes decisions. Are these policies substitutes for hard restrictions, and are delayed decisions more respected? In an experiment, decision-makers are informed about an impending high-stakes decision. Treatments define when the decision is made: on the spot or after one day, and whether the initial decision can be revised. In a general population survey experiment, another class of subjects (Choice Architects) is granted the opportunity to make rules for decision-makers. Given a decision's temporal structure, Choice Architects can decide on a cap to the decision-maker's risk taking. In another treatment, Choice Architects can implement a mandatory waiting period in addition to the cap. This allows us to study the substitutional relationship between waiting periods and paternalistic action and the effect of deliberation on the autonomy afforded to the decision-maker. Our highly powered experiment reveals that exogenous deliberation has no effect on the cap. Moreover, endogenously prescribed waiting periods represent add-on restrictions that do not substitute for the cap. Choice Architects believe that, with time, the average decision-maker will take less risk and---because of the distribution of Choice Architects' bliss points---come closer to Choice Architects' subjective ideal choice. These findings highlight the complementarity of policy tools in targeting various parts of a distribution of decision-makers.

• Integrating Machine Behavior into Human Subject Experiments (with Engel, C. & Ockenfels, A.)

  Working paper · GitHub · Interactive experiment builder · Revised & resubmitted to Experimental Economics · Abstract [−] Abstract [+]

  Large Language Models (LLMs) have the potential to profoundly transform and enrich experimental economic research. We propose a new software framework, "alter_ego", which makes it easy to design experiments between LLMs and to integrate LLMs into oTree-based web experiments with human subjects. Our toolkit is freely available at github.com/mrpg/ego. To illustrate, we run simple differently framed prisoner's dilemmas with interacting machines as well as with human-machine interaction.

• Public Support for Environmental Regulation: When Ideology Trumps Knowledge (with Dertwinkel-Kalt, M.)

  Working paper · Submitted · Abstract [−] Abstract [+]

  When environmental regulations are unpopular, policymakers often attribute resistance to information frictions and poor communication. We test this idea in the context of a major climate policy: Germany's Heating Law of 2023, which mandates the phase-out of fossil fuel heating. Through a survey experiment with property owners, we examine whether providing comprehensive information about the regulation's costs, requirements, and timeline affects adoption decisions and policy support. Despite successfully increasing factual knowledge, information provision has no significant effect on intended technology adoption, policy support, or incentivized measures of climate preferences. Instead, pre-existing environmental preferences and demographic characteristics emerge as the key predictors of responses to the regulation. A feeling that existing systems still work well and cost considerations dominate fossil fuel users' stated reasons for non-adoption, while independence from fossil fuels and perceived contributions to the common good drive adoption among switchers. Our findings suggest that opposition to climate policy stems from fundamental preference heterogeneity rather than information frictions. This has important implications for optimal policy design, highlighting potential limits of information provision in overcoming resistance to environmental regulation. The results also speak to broader questions in political economy about the relationship between knowledge, preferences, and support for policy reform.

• Paternalism in Data Sharing (with Ockenfels, A.)

  Abstract [−] Abstract [+]

  The privacy paradox is concerned with an ostensible inconsistency between stated and revealed preferences for data sharing: while many people claim to be concerned with privacy, their actual behavior shows little correlation with that concern. The existence of this paradox has recently been questioned on methodological grounds. We study an interpersonal privacy paradox that overcomes these challenges. We test a claim of inconsistency directly: do people want more privacy for others than themselves? We conduct an experiment in which Choosers can state a Willingness-to-Accept (WTA) for the publication of data about themselves. Another group of subjects, impartial policymakers (Choice Architects) can intervene in the Chooser's decision by imposing minimum and/or maximum prices to prevent publication even beyond the WTA. We find that 30 percent of Choice Architects set a minimum price, but only few set a maximum price. The WTA of Choice Architects who set a minimum-price tend to exceed the WTA of non-interventionist Choice Architects. When we correlate minimum prices to interventionists’ WTA, we find a strong relationship. Choice Architects don’t merely impose their WTA on Choosers: they grant Choosers some liberty to express their own preferences. Choice Architects do not appear to act inconsistently: they are not stricter towards Choosers than towards themselves. We find that beliefs over WTAs are strongly and systematically biased. The frequency of low WTAs is underestimated, while that of high WTAs is overestimated.

• uproot (with Gerhardt, H.)

  Project website · In progress (already used by some experiments!) · Abstract [−] Abstract [+]

  We introduce a new, advanced, and web-based experimental framework.

• Composing Optimal Teams (with Kölle, F., Quercia, S. & Sliwka, D.)

  Implementation stage

• LLM-Assisted Trading (with López Vargas, K.)

  Implementation stage

Publications in peer-reviewed journals

1. Reproducibility in Management Science (by Fišar, M., Greiner, B., Huber, C., Katok, E., Ozkes, A. and the Management Science Reproducibility Collaboration [consortium co-authorship])

   Management Science (2023), 70(3):1343-1356 · Published version

2. z-Tree unleashed: A novel client-integrating architecture for conducting z-Tree experiments over the Internet (with Duch, M. L. & Lauer, T.)

   Journal of Behavioral and Economic Finance (2020) · Published version · Abstract [−] Abstract [+]

   We present z-Tree unleashed, a novel approach and set of scripts to aid the implementation of computerized behavioral experiments outside the laboratory. z-Tree unleashed enables subjects to join the experiment using a web portal that requires no software apart from a web browser. Experimenters are likewise enabled to administer their experiments from anywhere in the world. Except for z-Tree itself, z-Tree unleashed is entirely based on free and open-source software. In this paper we give a high-level overview of z-Tree unleashed’s features and benefits and its design. We also show how to set up the server and demonstrate the steps required for conducting an entire experiment. We subsequently explain how to leverage the security and routing features of a virtual private network with z-Tree unleashed, enabling servers to securely run behind routers.

Experience

I manage the Cologne Laboratory for Economic Research, one of the largest experimental economics laboratories. I was an Oskar Morgenstern Fellow at the Mercatus Center at George Mason University. I have taken part in many seminars, conferences, research visits and summer schools abroad.

Technology

Among other things, I developed otree_slider and alter_ego. My main focus as a lab manager has been to enable researchers to effectively employ online methodologies.