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International audience; Dilemmas related to the use of environmental resources concern diverse populations at local or global scales. Frequently, individuals are unable to visualize the consequences of their actions, where they belong in the decision-making line, and have no information about past choices or the time horizon. We design a new one-shot extraction game to capture these dynamic decisions. We present results from a nationwide common pool resource experiment, conducted simultaneously in eleven French cities, involving a total of 2813 participants. We examine, for the first time, the simultaneous impact of several variables on the amount of resource extracted: the local vs. the national scale of the resource, the size of the group (small vs. big), the low vs. high recovery rate of the resource, and the available information. We show that individuals significantly reduce extraction levels in local as compared to national level dilemmas and that providing recommendations on sustainable extraction amounts significantly improves the sustainability of the resource. Overall, women extract significantly less, but care more about preserving the local resource; older participants extract significantly more resources but extract less from the national resource. Our experiment also fulfills a science popularization pedagogical aim, which we discuss..

International audience; Several physical features influence the perception of how cooperative a potential partner is. While previous work focused on face and voice, it remains unknown whether body odours influence judgements of cooperativeness and if odour-based judgements are accurate. Here, we first collected axillary odours of cooperative and uncooperative male donors through a public good game and used them as olfactory stimuli in a series of tasks examining whether and how they influence cooperative decision-making in an incentivized economic game and ratings of cooperativeness. Our results show that having access to the donor's body odours provided a strategic advantage to women during economic decisions (but not to men): with age, women were more likely to cooperate with cooperative men and to avoid interacting with uncooperative men. Ratings of cooperativeness were nonetheless unrelated to the donors’ actual cooperativeness. Finally, while men with masculine and intense body odours were judged less cooperative, we found no evidence that donors’ actual cooperativeness was associated with less masculine or less intense body odour. Overall, our findings suggest that, as faces and voices, body odours influence perceived cooperativeness and might be used accurately and in a non-aware manner as olfactory cues of cooperativeness, at least by women.

Smiling is a popular and powerful facial signal used to influence how we are judged and evaluated by others. The recent COVID pandemic made the use of facemasks common around the world. Since facemasks, when properly worn, cover the lower half of the face, a common concern with them is that they inhibit our ability to signal to others through facial expressions like smiles. In this paper, we show through three subsequent studies that smiling faces are easily distinguished from neutral faces even if the person is wearing a face mask (Study 1, N=1814). We further show that smiling behind a facemask significantly influences ratings regarding attractiveness, trustworthiness, and competence (Study 2, N=250). We finally show that individuals with about 18 months of experience with facemasks are well aware that smiling behind facemasks will influence ratings regarding attractiveness and trustworthiness by others (Study 3, N=94). Together, our studies provide evidence that facemasks should not be seen as a threat that inhibits simple non-verbal communication through smiles.

Single people are more likely to die from COVID-19. Here we study whether this higher death rate could be partly explained by differences in compliance with protective health measures against COVID-19 between single and married people, and the drivers of this marital compliance gap. Data collected from 46,450 respondents in 67 countries reveal that married people are more likely to comply with protective measures than single people. This marital gap in compliance is higher for men (approximately 5%) than for women (approximately 2%). These results are robust across a large range of countries and independent of country level differences with respect to culture, values or infection rates. Prosocial characteristics linked to morality and social belonging explain more than 38% of the marital gap, while individual risk perceptions play a minor role. These findings help explain single people's and particularly single men's greater vulnerability to COVID-19, which in turn can be leveraged to improve the effectiveness of international public policy campaigns aimed at promoting protective health measures.

Human prosociality is a valuable but also deeply puzzling trait. While several studies suggest that prosociality is an instinctive and impulsive behavior, others argue that patience and self-control are necessary to develop prosocial behaviors. Yet, prosociality and patience in children have rarely been studied jointly. Here, we measured patience (i.e. delay-of-gratification) and prosociality (i.e. giving in a dictator game to a known or unknown partner) in 250 4- to 6-year-old French schoolchildren. We found that sharing with an unknown partner was negatively linked to patience in children but observed no relationship between patience and sharing with a familiar partner. Taken together, our results support the hypothesis that children are intuitively prosocial independent of strategic concerns and that patience is therefore not necessary to act prosocially during early childhood. Future studies investigating whether and why prosociality show a non-linear developmental trajectory across the lifespan are warranted.

International audience; Excessive screen time during early childhood has been negatively associated with cognitive development, including poor academic success.1 Social integration2 and delayed gratification (ie patience), are key childhood factors that have been associated with positive achievements in later life.3 Despite this, little is known about the possible association between screen time and these childhood factors. This study fills a gap in our knowledge, by investigating the association between screen time; delayed gratification, which is waiting for a larger reward; and social integration, which is the number of times a child is called as a friend by their classmates.

National audience; Cooperation plays a key role in the development of advanced societies and can be stabilized through shared genes (kinship) or reciprocation. In humans, cooperation among kin occurs more readily than cooperation among non-kin. In many organisms, cooperation can shift with age (e.g. helpers at the nest); however, little is known about developmental shifts between kin and non-kin cooperation in humans. Using a cooperative game, we show that 3- to 10-year-old French schoolchildren cooperated less successfully with siblings than with non-kin children, whether or not non-kin partners were friends. Furthermore, children with larger social networks cooperated better and the perception of friendship among non-friends improved after cooperating. These results contrast with the well-established preference for kin cooperation among adults and indicate that non-kin cooperation in humans might serve to forge and extend non-kin social relationships during middle childhood and create opportunities for future collaboration beyond kin. Our results suggest that the current view of cooperation in humans may only apply to adults and that future studies should focus on how and why cooperation with different classes of partners might change during development in humans across cultures as well as other long-lived organisms.

National audience; Some economic transactions require people to trust strangers, whose trustworthiness is unknown. In these circumstances, behavioral studies have shown that adults (but not young adolescents) seem to have some minimal ability to detect the trustworthiness of adult strangers based on their facial features. In this study, we explored the neural correlates of this facial trustworthiness detection. A group of adolescents and adults played a series of economic Trust Games with adult trustees of which we had previously recorded the strategy. Results showed that when adult investors were looking at the picture of a trust-abusing trustee, the left amygdala was relatively more activated than when they were looking at a trust-honoring player. Younger adolescents did not show this pattern and responded with a more pronounced deactivation when facing a trust-abusing trustee. An exploratory whole-brain analysis detected a similar age shift for mentalizing regions of the brain. Our results fit with an emerging model suggesting that the amygdala is implicated in an associative learning process that progressively refines a mapping of faces onto trustworthy behavior and may result in avoiding to be exploited by untrustworthy strangers.

Contains fulltext : 228242.pdf (Publisher’s version ) (Open Access) Drawing on the concept of a gale of creative destruction in a capitalistic economy, we argue that initiatives to assess the robustness of findings in the organizational literature should aim to simultaneously test competing ideas operating in the same theoretical space. In other words, replication efforts should seek not just to support or question the original findings, but also to replace them with revised, stronger theories with greater explanatory power. Achieving this will typically require adding new measures, conditions, and subject populations to research designs, in order to carry out conceptual tests of multiple theories in addition to directly replicating the original findings. To illustrate the value of the creative destruction approach for theory pruning in organizational scholarship, we describe recent replication initiatives re-examining culture and work morality, working parents’ reasoning about day care options, and gender discrimination in hiring decisions. Significance statement It is becoming increasingly clear that many, if not most, published research findings across scientific fields are not readily replicable when the same method is repeated. Although extremely valuable, failed replications risk leaving a theoretical void - reducing confidence the original theoretical prediction is true, but not replacing it with positive evidence in favor of an alternative theory. We introduce the creative destruction approach to replication, which combines theory pruning methods from the field of management with emerging best practices from the open science movement, with the aim of making replications as generative as possible. In effect, we advocate for a Replication 2.0 movement in which the goal shifts from checking on the reliability of past findings to actively engaging in competitive theory testing and theory building. Scientific transparency statement The materials, code, and data for this article are posted publicly on the Open Science Framework, with links provided in the article. 19 p.

National audience; The sound of the voice has several acoustic features that influence the perception of how cooperative the speaker is. It remains unknown, however, whether these acoustic features are associated with actual cooperative behaviour. This issue is crucial to disentangle whether inferences of traits from voices are based on stereotypes, or facilitate the detection of cooperative partners. The latter is likely due to the pleiotropic effect that testosterone has on both cooperative behaviours and acoustic features. In the present study, we quantified the cooperativeness of native French‐speaking men in a one‐shot public good game. We also measured mean fundamental frequency, pitch variations, roughness, and breathiness from spontaneous speech recordings of the same men and collected saliva samples to measure their testosterone levels. Our results showed that men with lower‐pitched voices and greater pitch variations were more cooperative. However, testosterone did not influence cooperative behaviours or acoustic features. Our finding provides the first evidence of the acoustic correlates of cooperative behaviour. When considered in combination with the literature on the detection of cooperativeness from faces, the results imply that assessment of cooperative behaviour would be improved by simultaneous consideration of visual and auditory cues.

Emotion display serves as incentives or deterrents for others’ in many social interactions. We study the portrayal of anger and happiness, two emotions associated with dominance, and its relationship to team performance in a high stake environment. We analyze 4318 pictures of players from 304 participating teams in twelve editions (1970–2014) of the FIFA Soccer World Cup, and use automated face-reading (FaceReader 6) to evaluate the display of anger and happiness. We observe that the display of both anger and happiness is positively correlated with team performance in the World Cup. Teams whose players display more anger, an emotion associated with competitiveness, concede fewer goals. Teams whose players display more happiness, an emotion associated with confidence, score more goals. We show that this result is driven by less than half the players in a team. © 2018 Elsevier B.V.

Patience, or the ability to tolerate delay, is typically studied using delay of gratification (DoG) tasks. However, among other factors (e.g., type of reward), the use of a reward to test patience is affected by an individual’s motivation to obtain the reward (e.g., degree of preference for the small vs. large reward). In addition, DoG tasks do not assess the extent to which an individual can wait in the absence of an explicit reward—or what we term “patience as a virtue.” Accordingly, the current study used a new measure of patience—the “pure waiting paradigm”—in which 3- to 5-year-old children waited 3 min with nothing to do and with no explicit reward. We then examined the relation between performance on this task (as assessed by children’s spontaneous patient behaviors) and performance on two DoG tasks (candy and video rewards). Significant correlations were found between DoG performance and patient behaviors in the pure waiting paradigm, especially when controlling for motivation. These results and methodology show for the first time a direct link between patience as a virtue and DoG performance and also provide new insights about the study of patience in children.

The emotion that someone expresses has consequences for how that person is treated. We study whether people display emotions strategically. In two laboratory experiments, participants play task delegation games in which managers assign a task to one of two workers. When assigning the task, managers see pictures of the workers and we vary whether getting the task is desirable or not. We find that workers strategically adapt their emotional expressions to the incentives they face, and that it indeed pays off to do so. Yet, workers do not exploit the full potential of the strategic display of emotions.

International audience; Female specialization on household work and male specialization on labor-market work is a widely observed phenomenon across time and countries. This absence of gender neutrality with respect to work-division is known as the “work-division puzzle”. Gender differences regarding characteristics (preferences, productivity) and context (wage rates, social norms) are generally recognized as competing explanations for this fact. We experimentally control for context and productivity to investigate preferences for work-division by true co-habiting couples, in a newly developed specialization task. Efficiency in this task comes at the cost of inequality, giving higher earnings to the “advantaged” player. We compare behavior when men (or women) are in the advantaged position, which corresponds to the traditional (or power) couple case where he (or she) earns more. Women and men contribute equally to the household public good in all conditions. This result allows us to rule out some of the standard explanations of the work-division puzzle.

International audience; Birth order supposedly influences individuals' cooperative attitudes: firstborns are more family-oriented and favor their kin, while laterborns are more likely to turn to non-kin. However little direct experimental evidence exists concerning costly resource sharing between full siblings. The present study investigates sharing decisions with respect to a monetary resource by full sisters when either: (i) interacting with an unknown individual or (ii) their sister. A total of 112 sisters from 56 different families participated in an economic experiment regarding the distribution of an actual monetary reward. In line with kin selection theory, the results showed that participants favor their sister over strangers. Additionally, firstborns invested more costly resources in their sister (than laterborns) while they knew that the latter did not.

International audience; People can (to some extent) detect trustworthiness from the facial features of social partners,and populations which underperform at this task are at a greater risk of abuse. Herewe focus on situations in which adolescents make a decision whether to trust an unknownadult. Adolescents aged 13–18 (N = 540) played a trust game, in which they made decisionswhether to trust unknown adults based on their picture. We show that trusting decisionsbecome increasingly accurate with age, from a small effect size at age 13 to an effect size2.5 times larger at age 18. We consider the implications of this result for the developmentof prosociality and the possible mechanisms underlying the development of trustworthinessdetection from faces.

International audience; We present the implementation of an economic experiment conducted simultaneously in 11 French cities, with over 2700 participants, during four uninterrupted hours, during a popular-science event held in September 2015. Our goal is both to provide a roadmap for a possible replication and to discuss how the discipline can invest in new fields (science popularization, popular education, public communication).; Nous présentons la mise en place d'une expérience lors d'un évènement grand public national, de manière simultanée dans 11 villes françaises, en septembre 2015. L’expérience a impliqué plus de 2700 participants et a duré quatre heures ininterrompues. L’objectif de cet article est à la fois de fournir une feuille de route pour une éventuelle réplication et de penser à la manière dont la discipline peut investir des terrains nouveaux (vulgarisation, pédagogie populaire, communication grand public).

Humans are willing to cooperate with each other for mutual benefit—and to accept the risk of exploitation. To avoid collaborating with the wrong person, people sometimes attempt to detect cooperativeness in others’ body language, facial features, and facial expressions. But how reliable are these impressions? We review the literature on the detection of cooperativeness in economic games, from those with protocols that provide a lot of information about players (e.g., through long personal interactions) to those with protocols that provide minimal information (e.g., through the presentation of passport-like pictures). This literature suggests that people can detect cooperativeness with a small but significant degree of accuracy when they have interacted with or watched video clips of other players, but that they have a harder time extracting information from pictures. The conditions under which people can detect cooperation from pictures with better than chance accuracy suggest that successful cooperation detection is supported by purely intuitive processes.

Two disparate views of the sexual division of labour have dominated the 53 representation of intra-household resource allocations. These joint and separate interests 54 views differ in their interpretation of the relative roles of men and women, and make different 55 predictions about the extent to which marriage promotes economic efficiency (i.e. maximized 56 household production). Using an experimental “distribution task” stipulating a trade-off 57 between household efficiency and spousal equality in allocating surpluses of meat and 58 money, we examine factors influencing spousal distribution preferences among Tsimane 59 forager-horticulturalists of Bolivia (n=53 couples). Our primary goal is to understand whether 60 and how access to perfectly fungible and liquid resources – which increases with greater 61 participation in market economies – shifts intra-household distribution preferences. We 62 hypothesize that greater fungibility of money compared to meat results in greater squandering 63 of money for individual fitness gain at a cost to the family. Money therefore requires costly 64 strategies to insure against a partner’s claims for consumption. Whereas nearly all Tsimane 65 spouses prefer efficient meat distributions, we find a substantially reduced efficiency 66 preference for money compared to meat controlling for potential confounders (adjusted 67 OR=0.087, 95% CI: 0.02-0.38). Reported marital conflict over paternal disinvestment is 68 associated with a nearly 13-fold increase in odds of revealing a selfish money distribution 69 preference. Selfish husbands are significantly more likely than other husbands to be paired 70 with selfish wives. Lastly, Tsimane husbands and wives are more likely than Western 71 Europeans to prefer an efficient money distribution, but Tsimane wives are more likely than 72 Western European wives to exhibit a selfish preference. In sum, preferences for the 73 distribution of household production surplus support joint and separate interests views of 74 marriage; a hybrid approach best explains how ecological-, family-, and individual-level 75 factors influence spousal preferences through their effects on perceptions of marginal gains 76 within and outside the household.

Research on trustworthiness perception from faces has unfolded in a way that is strikingly reminiscent of Jussim's narrative in his 2012 book. Jussim's analysis warns us against overemphasizing evidence about prejudice over evidence about accuracy, when both are scant; and reminds us to hold all accounts to the same standards, whether they call on societal biases or true signals.

Abstract. Economic interactions often imply to gauge the trustworthiness of others. Recent studies showed that when making trust decisions in economic games, people have some accuracy in detecting trustworthiness from the facial features of unknown partners. Here we provide evidence that this face-based trustworthiness detection is a fast and intuitive process by testing its performance at split-second levels of exposure. Participants played a Trust game, in which they made decisions whether to trust another player based on their picture. In two studies, we manipulated the exposure time of the picture. We observed that trustworthiness detection remained better than chance for exposure times as short as 100 ms, although it disappeared with an exposure time of 33 ms. We discuss implications for ongoing debates on the use of facial inferences for social and economic decisions.

International audience; This study makes a significant contribution to investigations of household behavior by testing for a willingness to cooperate and share income by men and women who are either in couple with each other or complete strangers. We present results from an economic experiment conducted with 100 co-habiting heterosexual couples. We compare defection behavior in the prisoner’s dilemma within real couples to pairs of strangers. One out of four participants chose not to cooperatewith their spouse. To understand why spouses might prefer defection, we use a novel allocation task to elicit the individual’s trade-off between efficiency and equality within a couple. We further investigate the impact of socio-demographic and psychological characteristics of the couples. We find in particular that lack of preferences for joint income maximization, having children and being married lead to higher defection rates in the social dilemma.

International audience; We study the impact of social ties on behavior in two types of asymmetric coordination games. Social ties are varied by making players interact with partners from different in-groups (fellow members of their own sports team, members of their sports club, students of their university). Subjective social ties are further measured by direct questionnaires. We find that smaller and more salient in-groups lead to significantly more group beneficial choices. The same effect is observed for players that report high values of their subjective social ties. We discuss the implication of these results for theories assuming that socially tied individuals follow some group beneficial reasoning.

The two-dimensional map by Bentley et al. concerns decision-making and not games. The east–west dimension is interpreted as the level at which individuals identify with some larger group. We think that this should be linked to the concept of social ties. We argue that social ties will lead to different outcomes in the “north” compared to the “south.”

Online offences are generally considered as frequent and intentional acts performed by a member with the aim to deceive others. However, an offence may also be unintentional or exceptional, performed by a benevolent member of the community. This article examines whether a victim's decrease in trust towards an unintentional or occasional offender can be repaired in an online setting, by designing and evaluating systems to support forgiveness. We study which of three systems enable the victim of a trust breakdown to fairly assess this kind of offender. The three systems are: (1) a reputation system, (2) a reputation system with a built-in apology forum that may display the offender's apology to the victim and (3) a reputation system with a built-in apology forum that also includes a ''forgiveness'' component. The ''forgiveness'' component presents the victim with information that demonstrates the offender's trustworthiness as judged by the system. We experimentally observe that systems (2) and (3), endorsing apology and supporting forgiveness, allow victims to recover their trust after online offences. An apology from the offender restores the victim's trust only if the offender cooperates in a future interaction; it does not alleviate the trust breakdown immediately after it occurs. By contrast, the ''forgiveness'' component restores the victim's trust directly after the offence and in a subsequent interaction. The applicability of these findings for extending reputation systems is discussed.

From the viewpoint of the independence axiom of expected utility theory, an interesting empirical dynamic choice problem involves the presence of a “global risk,” that is, a chance of losing everything whichever safe or risky option is chosen. In this experimental study, participants have to allocate real money between a safe and a risky project. Treatment variable is the particular decision stage at which a global risk is resolved: (i) before the investment decision; (ii) after the investment decision, but before the resolution of the decision risk; (iii) after the resolution of the decision risk. The baseline treatment is without global risk. Our goal is to investigate the isolation effect and the principle of timing independence under the different timing options of the global risk. In addition, we examine the role played by anticipated and experienced emotions in the choice problem. Main findings are a violation of the isolation effect, and support for the principle of timing independence. Although behavior across the different global risk cases shows similarities, we observe clear differences in people’s affective responses. This may be responsible for the conflicting results observed in earlier experiments. Dependent on the timing of the global risk different combinations of anticipated and experienced emotions influence decision making. This discussion paper has resulted in a publication in 'Theory and Decision', 2008, 64, 2-3, 249-300.

Although reciprocity is a key concept in the social sciences, it is still unclear why people engage in costly reciprocation. In this study, physiological and self-report measures were employed to investigate the role of emotions, using the Power-to-Take Game. In this two-person game, player 1 can claim any part of player 2’s resources, and player 2 can react by destroying some (or all) of these resources thus preventing their transfer to player 1. Both physiological and self-report measures were related to destruction decisions. The observed pattern of emotional arousal and its correlation with self-reported anger provides support for using both techniques to study reciprocity.

We analyse simulations reported in "The co-evolution of individual behaviors and social institutions" by Bowles et al., 2003 in the Journal of Theoretical Biology 223, 135-147, and begin with distinguishing two types of group selection models. The literature does not provide different names for them, but they are shown to be fundamentally different and have quite different empirical implications. The working of the first one depends on the answer to the question "is the probability that you also are an altruist large enough", while the other needs an affirmative answer to "are our interests enough in line". The first one therefore can also be understood as a kin selection model, while the working of the second can also be described in terms of the direct benefits. The actual simulation model is a combination of the two. It is also a Markov chain, which has important implications for how the output data should be handled.

International audience; We test the hypothesis that smiles perceived as honest serve as a signal that has evolved to induce cooperation in situations requiring mutual trust. Potential trustees (84 participants from Toulouse, France) made two video clips averaging around 15 seconds for viewing by potential senders before the latter decided whether to ‘send’ or ‘keep’ a lower stake (4 euro) or higher stake (8 euro). Senders (198 participants from Lyon, France) made trust decisions with respect to the recorded clips. If money was sent to the trustee, stakes were tripled and trustees could decide to keep all, two thirds or one half of the tripled stakes. Clips were further rated concerning the genuineness of the displayed smiles. We observe that smiles rated as more genuine strongly predict judgments about the trustworthiness of trustees, and willingness to send them money. We observe a relation between costs and benefits: smiles from trustees playing for higher stakes are rated as significantly more genuine. Finally, we show that those rated as smiling genuinely return more money on average to senders. An increase of one standard deviation in rating of smile genuineness is associated with an unconditional expected gain of about one dollar and thirty cents to senders in the two trials of the experiment. Potential gains for senders could be significantly increased from taking smiles rated as genuine into account.

International audience; This paper investigates the influence that social ties can have on behavior. After defining the concept of social ties that we consider, we introduce an original model of social ties. The impact of such ties on social preferences is studied in a coordination game with outside option. We provide a detailed game theoretical analysis of this game while considering various types of players, i.e., self-interest maximizing, inequity averse, and fair agents. In addition to these approaches that require strategic reasoning in order to reach some equilibrium, we also present an alternative hypothesis that relies on the concept of team reasoning. After having discussed the differences between the latter and our model of social ties, we show how an experiment can be designed so as to discriminate among the models presented in the paper.

International audience; In a recent article in the Science & Society section of this journal [1], Olivola and colleagues delivered a powerful argument about fighting the phenomenon that they called ‘face-ism’.

We analyze how Costa Rican coffee farmer's behavior in an experimental public good game depends on the institutional structure of the farmers buying point (cooperativevs.privately owned mills), and on the background of their game partners (partners selling to the same type of mill or not). We find that cooperative farmers do not display more public good orientation than private market farmers when playing with partners from the same type of mill. However, though farmers selling to private mills make no difference with respect to the background of partners, farmers selling to cooperatives significantly decrease contributions when paired with non-cooperative members. Finally, we study how self-selection into a mechanism that punishes the lowest contributors effects contributions both inside the group and with partners of the opposite background, and we show that it increases contributions by cooperative farmers interacting with non-cooperative farmers by more than 100%.

Testosterone administration appears to make individuals less trusting, and this effect has been interpreted as an adaptive adjustment of social suspicion, that improved the accuracy of trusting decisions. Here, we consider another possibility, namely that testosterone increases the subjective cost of being duped, decreasing the propensity to trust without improving the accuracy of trusting decisions. In line with this hypothesis, we show that second-to-fourth digit ratio (2D : 4D, a proxy for effects of testosterone in the foetus) correlates with the propensity to trust, but not with the accuracy of trusting decisions. Trust game players ( n = 144) trusted less when they had lower 2D : 4D (high prenatal testosterone), but their ability to detect the strategy of other players was constant (and better than chance) across all levels of digit ratio. Our results suggest that early prenatal organizing effects of testosterone in the foetus might impair rather than boost economic outcomes, by promoting indiscriminate social suspicion.

The capacity to trust wisely is a critical facilitator of success and prosperity, and it has been conjectured that people of higher intelligence were better able to detect signs of untrustworthiness from potential partners. In contrast, this article reports five Trust Game studies suggesting that reading trustworthiness on the faces of strangers is a modular process. Trustworthiness detection from faces is independent of general intelligence (Study 1) and effortless (Study 2). Pictures that include non-facial features such as hair and clothing impair trustworthiness detection (Study 3) by increasing reliance on conscious judgments (Study 4), but people largely prefer to make decisions from this sort of pictures (Study 5). In sum, trustworthiness detection in an economic interaction is a genuine and effortless ability, possessed in equal amount by people of all cognitive capacities, but whose impenetrability leads to inaccurate conscious judgments and inappropriate informational preferences.

Investment behavior is traditionally investigated with the assumption that risky investment is on average advantageous. However, this may not always be the case. In this paper, we experimentally studied investment choices made by students and financial professionals under favorable and unfavorable market conditions in a multi-round investment game. In particular, the probability of winning was set so that investment in one condition was advantageous, and in one condition was disadvantageous. To investigate who is more likely to adapt their investment behaviors to the changing market conditions, we also measured personality and self-efficacy. We expected that investment behavior in changing markets could be predicted by a combination of experience (students, professionals), personality (anxiety, optimism, impulsivity, and Openness to Experience), and self-efficacy (belief in one’s ability to make good decisions in an investment task). Results indicate that professionals do not significantly differ from students in their decisions. Personality and self-efficacy both predicted investment behavior. In particular, we found that optimism and anxiety were a liability in unfavorable markets, leading to unreasonable levels of risk. Impulsivity was a liability in both favorable and unfavorable markets, leading to high risk on unfavorable markets, and low risk in favorable markets. Openness to experience was an asset in unfavorable markets, leading to adjusted risk taking. Finally, self-efficacy was generally related to higher levels of risk.

This discussion paper has resulted in a publication in the 'Journal of Economic Psychology' 32(6) 918-39.This experimental study is concerned with the impact of the timing of the resolution of risk onpeople's willingness to take risks, with a special focus on the role of affect. While the importanceof anticipatory emotions has so far been only inferred from decisions regarding hypothetical choiceproblems, we had participants put their own money at risk in a real investment task. Moreover,emotions were explicitly measured, including anticipatory emotions experienced during the waitingperiod under delayed resolution (which involved two days). Affective traits and risk attitudes weremeasured through a web-based questionnaire before the experiment and participants' preferencesfor resolution timing, risk, and time were incentive compatibly measured during the experiment.Main findings are that delayed resolution can affect investment, that the effect depends on the riskinvolved, and that (among all the measures considered) only emotions can explain our results,albeit in ways that are not captured by existing models.

From the viewpoint of the independence axiom of expected utility theory, an interesting empirical dynamic choice problem involves the presence of a global risk, that is, a chance of losing everything whichever safe or risky option is chosen. In this experimental study, participants have to allocate real money between a safe and a risky project. Treatment variable is the particular decision stage at which a global risk is resolved: (i) before the investment decision; (ii) after the investment decision but before the resolution of the investment risk; (iii) after the resolution of the investment risk. The baseline treatment is without global risk. Our goal is to investigate the isolation effect and the principle of timing independence under the different timing options of the global risk. In addition, we examine the role played by anticipated and experienced emotions in the choice problem. Main findings are a violation of the isolation effect, and support for the principle of timing independence. Although behavior across the different global risk cases shows similarities, we observe clear differences in people's affective responses. This may be responsible for the conflicting results observed in earlier experiments. Dependent on the timing of the global risk different combinations of anticipated and experienced emotions influence decision making.

This paper experimentally explores how the enforcement of cooperative behavior in a social dilemma is facilitated through institutional as well as emotional mechanisms. Recent studies emphasize the importance of negatively valued emotions, such as anger, which motivate individuals to punish free riders. However, these types of emotions also trigger retaliatory behavior by the punished individuals. This makes the enforcement of a cooperative norm more costly. We show that in addition to anger, ‘social’ emotions like shame and guilt need to be present for punishment to be an effective deterrent of uncooperative actions. They play a key role by subduing the desire of punished individuals to retaliate and by motivating them to behave more cooperatively in the future.

This paper experimentally explores how the enforcement of cooperative behavior in a social dilemma is facilitated through institutional as well as emotional mechanisms. Recent studies emphasize the importance of negatively valued emotions, such as anger, which motivate individuals to punish free riders. However, these types of emotions also trigger retaliatory behavior by the punished individuals. This makes the enforcement of a cooperative norm more costly. We show that in addition to anger, 'social' emotions like shame and guilt need to be present for punishment to be an effective deterrent of uncooperative actions. They play a key role by subduing the desire of punished individuals to retaliate and by motivating them to behave more cooperatively in the future.

Although reciprocity is a key concept in the social sciences, it is still unclear why people engage in costly reciprocation. In this study, physiological and self-report measures were employed to investigate the role of emotions, using the Power-to-Take Game. In this 2-person game, player 1 can claim any part of player 2's resources, and player 2 can react by destroying some (or all) of these resources thus preventing their transfer to player 1. Both physiological and self-report measures were related to destruction decisions and expectations. The pattern of emotional arousal and its correlation with self-reported anger highlights the importance of using both techniques for studying reciprocity.This discussion paper has led to a publication in Journal of Public Psychology (2007) 28, 314-23.

We present agent-based simulations of a model of a deme-structured population in which group differences in social institutions are culturally transmitted and individual behaviors are genetically transmitted. We use a standard extended fitness accounting framework to identify the parameter space for which this co-evolutionary process generates high levels of group-beneficial behaviors. We show that intergroup conflicts may explain the evolutionary success of both: (a) altruistic forms of human sociality towards unrelated members of one's group; and (b) group-level institutional structures such as food sharing which have emerged and diffused repeatedly in a wide variety of ecologies during the course of human history. Group-beneficial behaviors may evolve if (a) they inflict sufficient fitness costs on outgroup individuals and (b) group-level institutions limit the individual fitness costs of these behaviors and thereby attenuate within-group selection against these behaviors. Thus, the evolutionary success of individually costly but group-beneficial behaviors in the relevant environments during the first 90,000 years of anatomically modern human existence may have been a consequence of distinctive human capacities in social institution building.

Smiling can be interpreted as a costly signal of future benefits from cooperation between the individual smiling and the individual to whom the smile is directed. The target article by Niedenthal et al. gives little attention to the possible mechanisms by which smiling may have evolved. In our view, there are strong reasons to think that smiling has the key characteristics of a costly signal.

OpenAccess; International audience; We develop a theoretical model under which “genuine” or “convincing” smiling is a costly signal that has evolved to induce cooperation in situations requiring mutual trust. Prior to a trust interaction involving a decision by a sender to send money to a recipient, the recipient can emit a signal to induce the sender to trust them. The signal takes the form of a smile that may be perceived as more or less convincing, and that can be made more convincing with the investment of greater effort. Individuals differ in their degree of altruism and in their tendency to display reciprocity. The model generates three testable predictions. First, the perceived quality of the recipient’s smile is increasing in the size of the stake. Secondly, the amount sent by the sender is increasing in the perceived quality of the recipient’s smile. Thirdly, the expected gain to senders from sending money to the recipient is increasing in the perceived quality of the recipient’s smile.

The emotion that someone expresses has consequences for how that person is treated. We study whether people display emotions strategically. In two laboratory experiments, participants play task delegation games in which managers assign a task to one of two workers. When assigning the task, managers see pictures of the workers and we vary whether getting the task is desirable or not. We find that workers strategically adapt their emotional expressions to the incentives they face, and that it indeed pays off to do so. Yet, workers do not exploit the full potential of the strategic display of emotions.