(M. Basili, A. Muscillo and P. Pin)

Scientific Reports 12, 18132 (2022)

In September 2021 we conducted a survey to 1482 people in Italy, when the vaccination campaign against Covid19 was going on. In the first part of the survey we run three simple tests on players’ behavior in standard tasks with monetary incentives to measure their risk attitudes, willingness to contribute to a public good in an experimental game, and their beliefs about others’ behavior. In the second part, we asked respondents if they were vaccinated and, if not, for what reason. We classified as no-vaxxers those (around 12% of the sample) who did not yet start the vaccination process and declared that they intended not to do it in the future. We find that no-vaxxers contribute less to the public good in the experimental game because they trust others less to do so. from the three tests we extrapolated a classification based on the benchmark of rationality and other-regarding preferences for each respondent, and we found that in this respect no-vaxxers do not differ from the rest of the population.

(E. Bilancini and L. Boncinelli)

Games and Economic Behavior, Vol. 133, pp. 50-57 (2022)

We study the long-run convention emerging from stag hunt interactions when agents occasionally revise their action over time adopting a perturbed myopic best response rule, with the novelty of introducing social competition in the form of assignment of prizes to agents depending on the payoff ranking resulting from the stag hunt interaction. We find that social competition plays a crucial and articulated role in the selection of the long-run convention: indeed, a high enough reward from competition selects the payoff-dominant convention when competition is harsh, and the maximin convention when competition is mild.

Memory Retrieval and Harshness of Conflict in the Hawk-Dove Game

(E. Bilancini, L. Boncinelli, S. Ille and E. Vicario)

Economic Theory Bulletin, forthcoming (2022)

We study the long-run dynamics of a repeated non-symmetric Haw-Dove type interaction between agents of two different populations. Agents choose a strategy based on their previous experience with the other population by sampling from a collective memory of past interactions. We assume that the sample size differs between populations and define a measure of harshness of conflict in the Hawk-Dove interaction. We then show how the properties of the long-run equilibrium depend on the harshness of conflict and the relative length of the sample. In symmetric interactions, if conflict is harsh, the population which samples relatively more past interactions is able to appropriate a higher payoff in the long-run, while the population with a relatively smaller sample do so if conflict is mild. These results hold subject to constraints on the sample size which we discuss in detail. We further extend our results to non-symmetric Hawk-Dove games.

Social value orientation and conditional cooperation in the online one-shot public goods game

(E. Bilancini, L. Boncinelli and T. Celadin)

Journal of Economic Behavior & Organization, Vol. 200, pp. 243-272 (2022)

We ran two experimental studies where we explore the role of altruism and reciprocity in the online one-shot public good game and the extent to which they depend on cognition. In the first study we ran an experiment to see whether the disposition to donate (altruism and prosociality according to the Social Value Orientation scale, Murphy et al., 2011) and the disposition to reciprocate (disposition to be a conditional cooperator measured with strategy method, Fischbacher et al., 2012) explain contribution levels in the one-shot public goods game in an online setting. In the second study, we run a similar online experiment where we manipulate cognition by means of time pressure (to induce less deliberative decisions) and motivated delay (to induce more deliberative decisions). Overall, we find that: (i) the disposition to donate positively affects contributions and this effect is not substantially altered by time pressure and motivated delay; (ii) the disposition to reciprocate predicts contributions but only under motivated delay. Our experimental evidence suggests that in an online setting altruism is a source of explanation of contributions, while reciprocity is such only if a deliberative mode of cognition is fostered as the result of the motivated delay treatment.

Several scholars in the last decade have explored whether cooperation is intuitive or it requires deliberation. Here we study whether time pressure (where decision time is costly to experimental subjects) and motivated delay (where experimental subjects are required to write a motivation for their decisions) impact contributions to a one-shot public goods game and social norms associated to it, in particular descriptive and injunctive norms. We find that in the motivated delay group, relatively to the time pressure group, (i) contributions are higher, (ii) beliefs about others’ contributions (intended as a proxy for the descriptive norm) are higher, (iii) evaluations of the social appropriateness of contribution levels (intended as a proxy for the injunctive norm) are more extreme. We conclude that cognition, as affected by the switch from time pressure to motivated delay, impacts both cooperation and social norms in the public goods game.

Pairwise Interact-and-Imitate Dynamics

(E. Bilancini, L. Boncinelli, and N. Campigotto)

Scientific Reports, 11 (n.13221), 2021

This paper introduces and studies a class of evolutionary dynamics—pairwise interact‑and‑imitate dynamics (PIID)—in which agents are matched in pairs, engage in a symmetric game, and imitate the opponent with a probability that depends on the difference in their payoffs. We provide a condition on the underlying game, named supremacy, and show that the population state in which all agents play the supreme strategy is globally asymptotically stable. We extend the framework to allow for payoff uncertainty, and check the robustness of our results to the introduction of some heterogeneity in the revision protocol followed by agents. Finally, we show that PIID can allow the survival of strictly dominated strategies, leads to the emergence of inefficient conventions in social dilemmas, and makes assortment ineffective in promoting cooperation.

Personal norms in the online public good game

(M. Catola, S. D’Alessandro, P. Guarnieri, and V. Pizziol)

Economics Letters, 207, 110024 (2021)

This paper shows that personal norms have a prominent role in explaining pro-social contribution in an online public good game. This finding suggests that the role of social norms might be loosened when subjects are distanced and interaction occurs online and in complete anonymity. Moreover, we found no statistically significant difference between the elicited norms and the norms that were elicited in a group of subjects not facing the contribution task, thus ruling out a potential self-justification bias.

Personal and social norms in a multilevel public goods experiment

(M. Catola, S. D’Alessandro, P. Guarnieri, and V. Pizziol)

Discussion Papers del Dipartimento di Economia e Management – Università di Pisa, n. 272 (2021)

In this study we provide a novel measurement of personal normative beliefs, empirical expectations and normative expectations in the multilevel public goods game. The objective is twofold. On the one hand, we aim at investigating whether personal and social norms are reactive to variations in the relative efficiency of the public goods. On the other hand, we aim at understating which kind of norm better explains contribution to both the public goods. In our online experiment, personal norms, as elicited by personal normative beliefs, play a crucial role. They are both more reactive to efficiency gains and more in line with contribution decisions as efficiency increases. However, social norms, as elicited by empirical expectations and normative expectations, still anchor contribution decisions to social expectations, especially when the efficiency of the related public good is relatively low. Moreover, we highlight a norm spillover effect among the public goods with the empirical expectations concerning one good impacting (negatively) the contribution to the other public good. This result reveals how norms referred to alternative reference networks may interact with each other and possibly conflict.

Multilevel Public Goods Game: an Online Experiment

(M. Catola, S. D’Alessandro, P. Guarnieri, and V. Pizziol)

Discussion Papers del Dipartimento di Economia e Management – Università di Pisa, n. 263 (2020)

In the multilevel public goods games, subjects face a trade-off between contributing to the provision of a local good or a global good benefiting the whole society. Institutions may attempt to counteract ingroup favouritism by increasing the efficiency of the global public good. In an online experiment, we systematically address all the conflicting results concerning efficiency obtained in the literature. By gradually increasing the relative return of the global good, we find evidence of i. a levelling up in the contribution to the global good, ii. a substitution at the expenses of the local good, and iii. no evidence of an increase in the total contribution to the two groups (i.e. marginal crowding in). We also provide a measure of an intrinsic preference for the local group revealing in-group favouritism and a novel measure of an intrinsic preference for the global good revealing a motivation to contribute to the society independently of efficiency reasons.