On the elicitation and measurement of betrayal aversion

Betrayal aversion has been operationalized as the evidence that subjects demand a higher risk premium to take social risks compared to natural risks. This evidence has been first shown by Bohnet and Zeckhauser (2004) using an adaptation of the Becker-DeGroot-Marshak mechanism (BDM, Becker et al. (1964)). We compare their implementation of the BDM mechanism with a new version designed to facilitate subjects' comprehension. We find that, although the two versions produce different distributions of values, the size of betrayal aversion, measured as an average treatment difference between social and natural risk settings, is not different across the two versions. We further show that our implementation is preferable to use in practice as it reduces substantially subjects' mistakes and hence the likelihood of noisy valuations

Affirmative action and retaliation in experimental contests

We conduct a real-effort experiment to test the effects of an affirmative action policy that reserves a share of the prize to subjects of a disadvantaged category in rent-seeking contests. We test three potential pitfalls of the affirmative action policy: (i) whether the introduction of the policy distorts effort and selection in the contest, (ii) whether it leads to reverse discrimination, that is, discourages entry from the advantaged category and (iii) whether the possibility of ex-post retaliatory actions undermines the effectiveness of the policy. We find that the affirmative action contest increases entry of players from the disadvantaged category without affecting entry of advantaged players. This increases overall effort in the contest. However, we find that the possibility of retaliation can undermine the benefits of the affirmative action policy reducing contest participation. This suggests that retaliation is an important aspect to consider when implementing affirmative action policies. (C) 2018 Elsevier B.V. All rights reserved

Cooperation in small groups: the effect of group size

We study the effect of group size on cooperation in voluntary contribution mechanism games. As in previous experiments, we study four- and eight-person groups in high and low marginal per capita return (MPCR) conditions. We find a positive effect of group size in the low MPCR condition, as in previous experiments. However, in the high MPCR condition we observe a negative group size effect. We extend the design to investigate two- and three-person groups in the high MPCR condition, and find that cooperation is highest of all in two-person groups. The findings in the high MPCR condition are consistent with those from n-person prisoner’s dilemma and oligopoly experiments that suggest it is more difficult to sustain cooperation in larger groups. The findings from the low MPCR condition suggest that this effect can be overridden. In particular, when cooperation is low other factors, such as considerations of the social benefits of contributing (which increase with group size), may dominate any negative group size effect

Conditional Cooperation and Betrayal Aversion

We investigate whether there is a link between conditional cooperation and betrayal aversion. We use a public goods game to classify subjects by type of contribution preference and by belief about the contributions of others; and we measure betrayal aversion for different categories of subject. We find that, among conditional cooperators, only those who expect others to contribute little to the public good are significantly betrayal averse, while there is no evidence of betrayal aversion for those who expect substantial contributions by others. This is consistent with their social risk taking in public goods games, as the pessimistic conditional cooperators tend to avoid contribution to avoid exploitation, whereas the optimistic ones typically contribute to the public good and thus take the social risk of being exploited

Conditional cooperation and betrayal aversion

We investigate whether there is a link between conditional cooperation and betrayal aversion. We use a public goods game to classify subjects by type of contribution preference and by belief about the contributions of others; and we measure betrayal aversion for different categories of subject. We find that, among conditional cooperators, only those who expect others to contribute little to the public good are significantly betrayal averse, while there is no evidence of betrayal aversion for those who expect substantial contributions by others. This is consistent with their social risk taking in public goods games, as the pessimistic conditional cooperators tend to avoid contribution to avoid exploitation, whereas the optimistic ones typically contribute to the public good and thus take the social risk of being exploited

Social Preferences under the Shadow of the Future

Social interactions predominantly take place under the shadow of the future. Previous literature explains cooperation in indefinitely repeated prisoner’s dilemma as predominantly driven by self-interested strategic considerations. This paper provides a causal test of the importance of social preferences for cooperation, varying the composition of interactions to be either homogeneous or heterogeneous in terms of these preferences. Through a series of pre-registered experiments (N = 1,074), we show that groups of prosocial individuals achieve substantially higher levels of cooperation. The cooperation gap between prosocial and selfish groups persists even when the shadow of the future is increased to make cooperation attractive for the selfish and when common knowledge about group composition is removed

Conditional Cooperation and Betrayal Aversion

We investigate whether there is a link between conditional cooperation and betrayal aversion. We use a public goods game to classify subjects by type of contribution preference and by belief about the contributions of others; and we measure betrayal aversion for different categories of subject. We find that, among conditional cooperators, only those who expect others to contribute little to the public good are significantly betrayal averse, while there is no evidence of betrayal aversion for those who expect substantial contributions by others. This is consistent with their social risk taking in public goods games, as the pessimistic conditional cooperators tend to avoid contribution to avoid exploitation, whereas the optimistic ones typically contribute to the public good and thus take the social risk of being exploited

User Characteristics in Explainable AI: The Rabbit Hole of Personalization?

As Artificial Intelligence (AI) becomes ubiquitous, the need for Explainable AI (XAI) has become critical for transparency and trust among users. A significant challenge in XAI is catering to diverse users, such as data scientists, domain experts, and end-users. Recent research has started to investigate how users' characteristics impact interactions with and user experience of explanations, with a view to personalizing XAI. However, are we heading down a rabbit hole by focusing on unimportant details? Our research aimed to investigate how user characteristics are related to using, understanding, and trusting an AI system that provides explanations. Our empirical study with 149 participants who interacted with an XAI system that flagged inappropriate comments showed that very few user characteristics mattered; only age and the personality trait openness influenced actual understanding. Our work provides evidence to reorient user-focused XAI research and question the pursuit of personalized XAI based on fine-grained user characteristics.Comment: 20 pages, 4 tables, 2 figure

Preferences and Perceptions in Provision and Maintenance Public Goods

We study two generic versions of public goods problems: in Provision problems, the public good does not exist initially and needs to be provided; in Maintenance problems, the public good already exists and needs to be maintained. In four lab and online experiments (,105), we document a robust asymmetry in preferences and perceptions in two incentive-equivalent versions of these public good problems. We find fewer conditional cooperators and more free riders in Maintenance than Provision, a difference that is replicable, stable, and reflected in perceptions of kindness. Incentivized control questions administered before gameplay reveal dilemma-specific misperceptions but controlling for them neither eliminates game-dependent conditional cooperation, nor differences in perceived kindness of others' cooperation. Thus, even when sharing the same game form, Maintenance and Provision are different social dilemmas that require separate behavioral analyses

From lifetime to evolution: Timescales of human gut microbiota adaptation

Human beings harbor gut microbial communities that are essential to preserve human health. Molded by the human genome, the gut microbiota (GM) is an adaptive component of the human superorganisms that allows host adaptation at different timescales, optimizing host physiology from daily life to lifespan scales and human evolutionary history. The GM continuously changes from birth up to the most extreme limits of human life, reconfiguring its metagenomic layout in response to daily variations in diet or specific host physiological and immunological needs at different ages. On the other hand, the microbiota plasticity was strategic to face changes in lifestyle and dietary habits along the course of the recent evolutionary history, that has driven the passage from Paleolithic hunter-gathering societies to Neolithic agricultural farmers to modern Westernized societie