Research

• We experimentally study conciliation, an intervention aimed at improving bargaining efficiency. In conciliation, a neutral third party collaborates with the parties by suggesting resolutions to promote agreements. Unlike delegation or arbitration, conciliation fully preserves the autonomy of the parties. Unlike mediation, the conciliator cannot filter information. Whether conciliation can improve bargaining efficiency is an open question.  In our laboratory experiment, two ``litigants'' bargain over the split of a loss in an unstructured protocol. In case of failure, a random split is implemented. In some conditions, a third party, the conciliator takes part in the bargaining by submitting non-binding suggestions to the litigants.  We find that, on average, conciliation does not affect the likelihood of failure or the splits that are agreed upon by litigants. However, for bargaining pairs composed of selfish litigants, conciliation leads to more equal agreements. Conciliation also reduces bargaining delays: the time and the number of offers necessary to converge to an agreement are significantly reduced in the presence of a conciliator. 

• In sequential social dilemmas with stranger matching, initiating cooperation is inherently risky for the first mover. The disclosure of the second mover's past actions may be necessary to instigate cooperation. We experimentally compare the effect of mandatory and voluntary disclosure with non-disclosure in a sequential prisoner's dilemma situation. Our results confirm the positive effects of disclosure on cooperation. We also find that voluntary disclosure is as effective as mandatory one, which, is surprising given the results of existing literature on this topic. With voluntary disclosure, second movers with a good track record decided to disclose because they, expect that not disclosing signals non-cooperativeness. First movers interpret nondisclosure, correctly as a signal of non-cooperativeness. Therefore, they cooperate, less than half as often when the second mover does not disclose.

• Home assistant chat-bots, self-driving cars, drones or automated negotiations are some of the several examples of autonomous (artificial) agents that have pervaded our society. These agents enable the automation of multiple tasks, saving time and (human) effort. However, their presence in social settings raises the need for a better understanding of their effect on social interactions and how they may be used to enhance cooperation towards the public good, instead of hindering it. To this end, we present an experimental study of human delegation to autonomous agents and hybrid human-agent interactions centered on a public goods dilemma shaped by a collective risk. Our aim to understand experimentally whether the presence of autonomous agents has a positive or negative impact on social behaviour, fairness and cooperation in such a dilemma. Our results show that cooperation increases when participants delegate their actions to an artificial agent that plays on their behalf. Yet, this positive effect is reduced when humans interact in hybrid human-agent groups. Finally, we show that humans are biased towards agent behaviour, assuming that they will contribute less to the collective effort. 

• We study the production of social image in social groups. In our experiment, we recruit pairs of real-life friends and study whether rule breaking in the form of misreporting decreases when misreporting may have negative spillovers on the image of the friend. We find that participants hurt their friends’ social image by misreporting: external observers update their beliefs and rightfully expect that a participant whose friend misreported is likely to misreport himself. However, participants misreport as often when their behavior can hurt the friend’s image as when it cannot, even though hurting their friends’ image reduces their own monetary gains. Our interpretation is that they underestimate the impact of their behavior on external observers’ beliefs about their friends. Our results show that, even in our case where group membership is salient, groups might have difficulties building a good image. 

• We experimentally test whether the gap between reference and actual income impactssubsequent altruism. Participants first perform a real-effort task for a fixed wage andthen play a dictator game. Between conditions, we vary the level and the timing of therevelation of the wage. In some conditions, participants know the wage before the realeffort task and are not informed of the other potential levels. In some other conditions,they are informed of the distribution of wages before the real effort task, but the actualwage is only revealed afterward. Participants in the latter conditions can formreferences that may be higher or lower than their actual wage. Our hypothesis is thatthe gap between the reference and the actual wage impacts transfers in thesubsequent dictator game, either because participants want to compensate their recentlosses, or because of the emotional reaction to gains and losses. The results supportthis hypothesis: participants who get the low wage transfer less and are less likely totransfer when they are informed of the other potential levels than when they are not.Conversely, participants who get the high wage are more likely to transfer positiveamounts when they are informed of the other potential levels. We use physiological(skin conductance response) and declarative data to discuss the role of emotions inour treatment effects.

• • In a laboratory experiment we test the interaction effects of group identity and status on interpersonal trust. Natural group identity is generated by school affiliation. Status (expert or agent) is awarded based on the relative performance in a math quiz that is ex ante less favorable to the subjects from one group. We find that “promoted”trustors (individuals from the disadvantaged group that nevertheless achieve the status of expert) trust less both in-group and out-group trustees, compared to the other members of their group. Status promotion singles out individuals and seems to weaken group identification. In contrast, trustworthiness is not affected by status and there is no evidence that interacting with promoted individuals impacts trust or trustworthiness.

This paper was awarded the ASFEE 2017 Prize for the best paper presented by a young researcher at the 2017 ASFEE conference in Rennes.

• Extracting from shared resources requires making choices to balance personal profit and sustainability. We present the results of a behavioural experiment wherein we manipulate the default extraction from a finite resource. Participants were exposed to two treatments -- pro-social or self-serving extraction defaults -- and a control without defaults. We examined the persistence of these nudges by removing the default after five rounds. Results reveal that a self-serving default increased the average extraction while present, whereas a pro-social default only decreased extraction for the first two rounds. Notably, the influence of defaults depended on individual inclinations, with cooperative individuals extracting more under a self-serving default, and selfish individuals less under a pro-social default. After the removal of the default, we observed no significant differences with the control treatment. Our research highlights the potential of defaults as cost-effective tools for promoting sustainability, while also advocating for a careful use to avoid adverse effects.

• Cooperation has many economic and social benefits, yet it is vulnerable to inequality. This study examines how the magnitude of inequality affects cooperation, focusing on differences in behavior between individuals randomly assigned to high (i.e. the rich) and low endowments (i.e. the poor). To do so, we use a novel dataset that pools individual-level observations from 24 published experimental linear public good games with unequal endowments. Pooling many studies allows us to study the causal effect of inequality at the participant level, with a substantial variation in levels of inequality. Such a variation would be very hard to get with a single, properly powered experiment.  We start by confirming that inequality reduces overall contributions, and that the rich contribute a lower share (``relative contribution'') of their endowment than the poor on average. We further identify a striking asymmetry: as inequality grows, the relative contributions of the rich decrease significantly, while the relative contributions of the poor are not significantly impacted. Therefore, the gap in contributions across statuses increases as inequality gets stronger. We provide a simple model of conditional cooperation that is compatible with our empirical findings. These results may inform the design of policies addressing inequality and social cohesion.

• Experimental evidence shows that in a repeated dilemma setting cooperation is more likely to become the norm in small matching groups than in large ones. This result holds even if cooperation is an equilibrium outcome for all investigated group sizes. But what happens if small matching groups are merged to become large ones? Our paper is based on the idea that due to norm spillovers, a large group created by a merger of small groups is more likely to cooperate than a large group of similar size that is created directly. We tested this idea experimentally in the context of an infinitely repeated prisoner's dilemma game. We compared the cooperation behavior of groups that result from mergers of smaller groups with the cooperation behavior of groups with constant group size. We found that cooperation levels were significantly higher in large groups that resulted from gradual growth than in large groups of the same size that were directly created. Looking at the individual behavior, we see that more subjects develop a norm of unconditional cooperation when the group size increases than when it is already large from the beginning. Hence, our results confirm the idea that cooperation is much more likely to be achieved when groups grow from small to large than when large groups are formed directly.