Ellingsen, T. and Mohlin, E. (2025) "A Model of Social Duties" accepted for publication in the Journal of Political Economy
Idea: We present a model of of duty-based motivation, distinguishing between duties of justice (proscriptions) and duties of charity (prescriptions). Duties of justice relate to entitlements, which can be identified from appropriateness ratings. The theory explains various experimental findings that other models struggle to explain.
Elication Experiment Instructions
This work largely replaces our previous working paper “Decency”
Mohlin, E., and Gärdenfors, P. (2025) "Ambiguity Aversion and Value Uncertainty Generates an Endowment Effect" Theory and Decision Preprint
Idea: Buyers tend to be more uncertain than sellers regarding the value of a good. Some of this uncertainty takes the form of ambiguity rather than plain risk. It follows that ambiguity aversion creates a wedge between WTA and WTP.
Duell, D., Mengel, F., Mohlin, E., and Weidenholzer, S. (2023) “Cooperation through collective punishment and participation” Political Science Research and Methods 1-27 Preprint
Idea: In an experiment we find that collective sanctions outperform individual sanctions as a means to enforce cooperation in public goods games when individual contributions are imperfectly observed.
Mohlin, E., Rigos, A. and Weidenholzer, S. (2023) “Emergence of Specialized Third Party Enforcement” Proceedings of the National Academy of Sciences (PNAS) Vol 120, No. 24, June 13, 2023
Idea: Question: who guards the guardians? Answer: the guardians guard themselves by means of reputation-based community enforcement in an indefinitely repeated game, in a way that is evolutionarily robust.
Old presentation 2014_01_28
Ellingsen, T., and Mohlin, E. (2023) “Puritanical Moralism May Signal Patience Rather Than Cause Self-Control” Behavioural and Brain Sciences 46 (open peer commentary for “The puritanical moral contract” by Fitouchi, André, & Baumard)
Idea: The target article argues that puritanical moralism induces behaviours that generate self-control. We argue that it may simply be a matter of puritanical moralism signalling traits that induce cooperation.
Mohlin, E., Östling, R., and Tao-yi Wang, J. (2020) “Learning by Similarity-weighted Imitation in Winner-takes-all Games” Games and Economic Behavior 120 (March), pp. 225-245. Preprint
Idea: We explain convergence to Nash equilibrium in field and lab experiments, by a model of “global cumulative imitation”, in which players imitate actions that are similar to actions that were successful in the past.
Bernergård, A., and Mohlin, E. (2019) “Evolutionary Selection against Iteratively Weakly Dominated Strategies” Games and Economic Behavior 117 (Sept.), pp. 82-97. Preprint
Idea: We identify a set of conditions on normal form games, ensuring that strategies that fail iterated elimination of iteratively weakly dominated strategies become extinct asymptotically, under any regular monotonic selection dynamic.
Rigos, A., Mohlin, E., and Ronchi, E. (2019) “The Cry Wolf Effect in Evacuation: A Game-Theoretic Approach” Physica A: Vol. 526, 15 July 2019, 120890. Preprint Mitchell and Webb on the topic
Idea: Alarms are needed to signal danger, but too many false alarms make people reluctant to evacuate. This dilemma is studied game-theoretically.
Heller, Y. & Mohlin, E. (2019) “Coevolution of Deception and Preferences: Darwin and Nash Meet Machiavelli” Games and Economic Behavior 113 (Jan), pp. 223-247. Preprint Presentation
Idea: We model coevolution of (i) preferences and (ii) the ability do deceive opponents about one’s preferences and intentions. Increased cognitive sophistication is costly but may allow one to exploit one’s opponents.
Heller, Y. & Mohlin, E. (2018) “Observations on Cooperation” Review of Economic Studies 85:4, pp. 2253–2282. Preprint Presentation
Idea: We examine under what conditions cooperation is stable in the Prisoners’ Dilemma, when players are randomly matched with a new opponent in every round, and before they take an action they are allowed to observe the outcome of a few of the opponent’s past interactions.
Heller, Y. & Mohlin, E. (2018) “Social Learning and the Shadow of the Past” Journal of Economic Theory 177, pp. 426–460. Preprint
Idea: We characterise the information structures that yield unique outcomes when a sample of the opponent’s past interactions are observed.
Mohlin, E. (2015) “A Metric for Measurable Partitions” Journal of Mathematical Psychology 67, pp. 39–44. Preprint
Idea: This paper proposes a metric that is defined for partitions that consist of countably many measurable cells/blocks. It can be applied to the psychology of colour categorization in natural languages.
Mohlin, E., Östling, R., & Tao-yi Wang, J. (2015) “Lowest Unique Bid Auctions with Population Uncertainty” Economics Letters 134, pp. 53-57. Preprint
Idea: We analyse the popular Lowest Unique Bid Auction. By assuming Poisson population uncertainty we are able to prove that there is a unique equilibrium and describe it.
Mohlin, E. (2014) “Optimal Categorization” Journal of Economic Theory 152, pp. 356–381. Preprint Presentation
Idea: This paper examines categorisations that are optimal from the point of view of minimising expected prediction error. The optimal number (and shape) of categories is determined by a bias-variance trade-off. This may shed light on the psychological phenomenon of basic level categories.
Mohlin, E. (2012) “Evolution of Theories of Mind” Games and Economic Behavior 75(1), pp. 299-312. Preprint + Supplement
Idea: Individuals have different strategic sophistication, as described by level-k theory, and related models of learning. I show that evolutionary selection does not eliminate unsophisticated individuals. Under plausible conditions, individuals with high and low levels of strategic sophistication may co-exist in evolutionarily stable populations.
*Gospic, K., *Mohlin, E., Fransson, P., Petrovic, P., Johannesson, M. & Ingvar, M. “Limbic Justice—Amygdala Involvement in Immediate Rejection in the Ultimatum Game”, (2011), PLoS Biology, 9(5). (* joint first authors)
Idea: We show that the amygdala plays a key role in rejection decisions in the ultimatum game.
Mohlin, E. (2010) “Internalized Social Norms in Conflicts: An Evolutionary Approach”, Economics of Governance 11(2), pp. 169-181. Preprint
Idea: This paper demonstrates that the amount of time that players have to learn (myopically) to play a game, decisively influences what preferences and norms that may survive.
Mohlin, E. & Johannesson M. (2008) “Communication: Content or Relationship?”, Journal of Economic Behavior and Organization, Vol. 65, pp. 409–419. Preprint
Idea: We show that communication increases donations in a dictator game both because messages create relationships and because messages contain arguments that are not relationship-specific.