Reducing discrimination against job seekers with and without employment gaps.

Past research shows that decision-makers discriminate against applicants with career breaks. Career breaks are common due to caring responsibilities, especially for working mothers, thereby leaving job seekers with employment gaps on their résumés. In a preregistered audit field experiment in the United Kingdom (n = 9,022), we show that rewriting a résumé so that previously held jobs are listed with the number of years worked (instead of employment dates) increases callbacks from real employers compared to résumés without employment gaps by approximately 8%, and with employment gaps by 15%. A series of lab studies (an online pilot and two preregistered experiments; n = 2,650) shows that this effect holds for both female and male applicants-even when compared to applicants without employment gaps-as well as and for applicants with less and more total job experience. The effect is driven by making the applicant's job experience salient, not as a result of novelty or ease of reading.

Deception about study purpose does not affect participant behavior.

The use of deception in research is divisive along disciplinary lines. Whereas psychologists argue that deception may be necessary to obtain unbiased measures, economists hold that deception can generate suspicion of researchers, invalidating measures and 'poisoning' the participant pool for others. However, experimental studies on the effects of deception, notably false-purpose deception-the most common form of experimental deception-are scarce. Challenges with participant attrition and avoiding confounds with a form of deception in which two related studies are presented as unrelated likely explain this scarcity. Here, we avoid these issues, testing within an experiment to what extent false-purpose deception affects honesty. We deploy two commonly used incentivized measures of honesty and unethical behavior: coin-flip and die-roll tasks. Across two pre-registered studies with over 2000 crowdsourced participants, we found that false-purpose deception did not affect honesty in either task, even when we deliberately provoked suspicion of deception. Past experience of deception also had no bearing on honesty. However, incentivized measures of norms indicated that many participants had reservations about researcher use of false-purpose deception in general-often considered the least concerning form of deception. Together, these findings suggest that while false-purpose deception is not fundamentally problematic in the context of measuring honesty, it should only be used as a method of last resort. Our results motivate further experimental research to study the causal effects of other forms of deception, and other potential spillovers.

Measuring inequality beyond the Gini coefficient may clarify conflicting findings.

Prior research has found mixed results on how economic inequality is related to various outcomes. These contradicting findings may in part stem from a predominant focus on the Gini coefficient, which only narrowly captures inequality. Here, we conceptualize the measurement of inequality as a data reduction task of income distributions. Using a uniquely fine-grained dataset of N = 3,056 US county-level income distributions, we estimate the fit of 17 previously proposed models and find that multi-parameter models consistently outperform single-parameter models (i.e., models that represent single-parameter measures like the Gini coefficient). Subsequent simulations reveal that the best-fitting model-the two-parameter Ortega model-distinguishes between inequality concentrated at lower- versus top-income percentiles. When applied to 100 policy outcomes from a range of fields (including health, crime and social mobility), the two Ortega parameters frequently provide directionally and magnitudinally different correlations than the Gini coefficient. Our findings highlight the importance of multi-parameter models and data-driven methods to study inequality.

(Mis)perceiving cooperativeness.

Cooperation is crucial for the success of social interactions. Given its importance, humans should readily be able to use available cues to predict how likely others are to cooperate. Here, we review the empirical literature on how accurate such predictions are. To this end, we distinguish between three classes of cues: behavioral (including past decisions), personal (including gender, attractiveness, and group membership) and situational (including the benefits to cooperation and the ability to communicate with each other). We discuss (i) how each cue correlates with future cooperative decisions and (ii) whether people correctly anticipate each cue's predictive value. We find that people are fairly accurate in interpreting behavioral and situational cues. However, they often misperceive the value of personal cues.

Climate Action for (My) Children.

How do we motivate cooperation across the generations-between parents and children? Here we study voluntary climate action (VCA), which is costly to today's decision-makers but essential to enable sustainable living for future generations. We predict that "offspring observability" is critical: parents will be more likely to invest in VCA when their own offspring observes their action, whereas when adults or genetically unrelated children observe them, the effect will be smaller. In a large-scale lab-in-the-field experiment, we observe a remarkable magnitude of VCA: parents invest 82% of their 69€ endowment into VCA, resulting in almost 14,000 real trees being planted. Parents' VCA varies across conditions, with the largest treatment effect occurring when a parent's own child is the observer. In subgroup analyses, we find that larger treatment effects occur among parents with a high school diploma. Moreover, VCA for parents who believe in climate change is most affected by the presence of their own child. In contrast, VCA of climate change skeptical parents is most influenced by the presence of children to whom they are not related. Our findings have implications for policy-makers interested in designing programs to encourage voluntary climate action and sustaining intergenerational public goods.

Ideology selectively shapes attention to inequality.

Contemporary debates about addressing inequality require a common, accurate understanding of the scope of the issue at hand. Yet little is known about who notices inequality in the world around them and when. Across five studies (N = 8,779) employing various paradigms, we consider the role of ideological beliefs about the desirability of social equality in shaping individuals' attention to-and accuracy in detecting-inequality across the class, gender, and racial domains. In Study 1, individuals higher (versus lower) on social egalitarianism were more likely to naturalistically remark on inequality when shown photographs of urban scenes. In Study 2, social egalitarians were more accurate at differentiating between equal versus unequal distributions of resources between men and women on a basic cognitive task. In Study 3, social egalitarians were faster to notice inequality-relevant changes in images in a change detection paradigm indexing basic attentional processes. In Studies 4 and 5, we varied whether unequal treatment adversely affected groups at the top or bottom of society. In Study 4, social egalitarians were, on an incentivized task, more accurate at detecting inequality in speaking time in a panel discussion that disadvantaged women but not when inequality disadvantaged men. In Study 5, social egalitarians were more likely to naturalistically point out bias in a pattern detection hiring task when the employer was biased against minorities but not when majority group members faced equivalent bias. Our results reveal the nuances in how our ideological beliefs shape whether we accurately notice inequality, with implications for prospects for addressing it.

Abrupt decline in tropospheric nitrogen dioxide over China after the outbreak of COVID-19.

China's policy interventions to reduce the spread of the coronavirus disease 2019 have environmental and economic impacts. Tropospheric nitrogen dioxide indicates economic activities, as nitrogen dioxide is primarily emitted from fossil fuel consumption. Satellite measurements show a 48% drop in tropospheric nitrogen dioxide vertical column densities from the 20 days averaged before the 2020 Lunar New Year to the 20 days averaged after. This decline is 21 ± 5% larger than that from 2015 to 2019. We relate this reduction to two of the government's actions: the announcement of the first report in each province and the date of a province's lockdown. Both actions are associated with nearly the same magnitude of reductions. Our analysis offers insights into the unintended environmental and economic consequences through reduced economic activities.

Evolving cooperation in multichannel games.

Humans routinely engage in many distinct interactions in parallel. Team members collaborate on several concurrent projects, and even whole nations interact with each other across a variety of issues, including trade, climate change and security. Yet the existing theory of direct reciprocity studies isolated repeated games. Such models cannot account for strategic attempts to use the vested interests in one game as a leverage to enforce cooperation in another. Here we introduce a general framework of multichannel games. Individuals interact with each other over multiple channels; each channel is a repeated game. Strategic choices in one channel can affect decisions in another. With analytical equilibrium calculations for the donation game and evolutionary simulations for several other games we show that such linkage facilitates cooperation. Our results suggest that previous studies tend to underestimate the human potential for reciprocity. When several interactions occur in parallel, people often learn to coordinate their behavior across games to maximize cooperation in each of them.

Social dilemmas among unequals.

Direct reciprocity is a powerful mechanism for the evolution of cooperation on the basis of repeated interactions1-4. It requires that interacting individuals are sufficiently equal, such that everyone faces similar consequences when they cooperate or defect. Yet inequality is ubiquitous among humans5,6 and is generally considered to undermine cooperation and welfare7-10. Most previous models of reciprocity do not include inequality11-15. These models assume that individuals are the same in all relevant aspects. Here we introduce a general framework to study direct reciprocity among unequal individuals. Our model allows for multiple sources of inequality. Subjects can differ in their endowments, their productivities and in how much they benefit from public goods. We find that extreme inequality prevents cooperation. But if subjects differ in productivity, some endowment inequality can be necessary for cooperation to prevail. Our mathematical predictions are supported by a behavioural experiment in which we vary the endowments and productivities of the subjects. We observe that overall welfare is maximized when the two sources of heterogeneity are aligned, such that more productive individuals receive higher endowments. By contrast, when endowments and productivities are misaligned, cooperation quickly breaks down. Our findings have implications for policy-makers concerned with equity, efficiency and the provisioning of public goods.

The critical role of second-order normative beliefs in predicting energy conservation.

Sustaining large-scale public goods requires individuals to make environmentally friendly decisions today to benefit future generations1-6. Recent research suggests that second-order normative beliefs are more powerful predictors of behaviour than first-order personal beliefs7,8. We explored the role that second-order normative beliefs-the belief that community members think that saving energy helps the environment-play in curbing energy use. We first analysed a data set of 211 independent, randomized controlled trials conducted in 27 US states by Opower, a company that uses comparative information about energy consumption to reduce household energy usage (pooled N = 16,198,595). Building off the finding that the energy savings varied between 0.81% and 2.55% across states, we matched this energy use data with a survey that we conducted of over 2,000 individuals in those same states on their first-order personal and second-order normative beliefs. We found that second-order normative beliefs predicted energy savings but first-order personal beliefs did not. A subsequent pre-registered experiment provides causal evidence for the role of second-order normative beliefs in predicting energy conservation above first-order personal beliefs. Our results suggest that second-order normative beliefs play a critical role in promoting energy conservation and have important implications for policymakers concerned with curbing the detrimental consequences of climate change.

(Mis)perceptions of inequality.

Laypeople's beliefs about the current distribution of outcomes such as income and wealth in their country influence their attitudes toward issues ranging from taxation to healthcare - but how accurate are these beliefs? We review the burgeoning literature on (mis)perceptions of inequality. First, we show that people on average misperceive current levels of inequality, typically underestimating the extent of inequality in their country. Second, we delineate potential causes of these misperceptions, including people's overreliance on cues from their local environment, leading to their erroneous beliefs about both the overall distributions of wealth and income and their place in those distributions. Third, we document that these (mis)perceptions of inequality - but not actual levels of inequality - drive behavior and preferences for redistribution. More promisingly, we review research suggesting that correcting misperceptions influences preferences and policy outcomes.

Think global, act local: Preserving the global commons.

Preserving global public goods, such as the planet's ecosystem, depends on large-scale cooperation, which is difficult to achieve because the standard reciprocity mechanisms weaken in large groups. Here we demonstrate a method by which reciprocity can maintain cooperation in a large-scale public goods game (PGG). In a first experiment, participants in groups of on average 39 people play one round of a Prisoner's Dilemma (PD) with their two nearest neighbours on a cyclic network after each PGG round. We observe that people engage in "local-to-global" reciprocity, leveraging local interactions to enforce global cooperation: Participants reduce PD cooperation with neighbours who contribute little in the PGG. In response, low PGG contributors increase their contributions if both neighbours defect in the PD. In a control condition, participants do not know their neighbours' PGG contribution and thus cannot link play in the PD to the PGG. In the control we observe a sharp decline of cooperation in the PGG, while in the treatment condition global cooperation is maintained. In a second experiment, we demonstrate the scalability of this effect: in a 1,000-person PGG, participants in the treatment condition successfully sustain public contributions. Our findings suggest that this simple "local-to-global" intervention facilitates large-scale cooperation.

Cooperating with the future.

Overexploitation of renewable resources today has a high cost on the welfare of future generations. Unlike in other public goods games, however, future generations cannot reciprocate actions made today. What mechanisms can maintain cooperation with the future? To answer this question, we devise a new experimental paradigm, the 'Intergenerational Goods Game'. A line-up of successive groups (generations) can each either extract a resource to exhaustion or leave something for the next group. Exhausting the resource maximizes the payoff for the present generation, but leaves all future generations empty-handed. Here we show that the resource is almost always destroyed if extraction decisions are made individually. This failure to cooperate with the future is driven primarily by a minority of individuals who extract far more than what is sustainable. In contrast, when extractions are democratically decided by vote, the resource is consistently sustained. Voting is effective for two reasons. First, it allows a majority of cooperators to restrain defectors. Second, it reassures conditional cooperators that their efforts are not futile. Voting, however, only promotes sustainability if it is binding for all involved. Our results have implications for policy interventions designed to sustain intergenerational public goods.

Heterogeneity in background fitness acts as a suppressor of selection.

We introduce the concept of heterogeneity in background fitness to evolutionary dynamics in finite populations. Background fitness is specific to an individual but not linked to its strategy. It can be thought of as a property that is related to the physical or societal position of an individual, but is not dependent on the strategy that is adopted in the evolutionary process under consideration. In our model, an individual's total fitness is the sum of its background fitness and the fitness derived from using a specific strategy. This approach has important implications for the imitation of behavioural strategies: if we imitate others for their success, but can only adopt their behaviour and not their social and economic ties, we may imitate in vain. We study the effect of heterogeneity in background fitness on the fixation of a mutant strategy with constant fitness. We find that heterogeneity suppresses selection, but also decreases the time until a novel strategy either takes over the population or is lost again. We derive analytical solutions of the fixation probability in small populations. In the case of large total background fitness in a population with maximum inequality, we find a particularly simple approximation of the fixation probability. Numerical simulations suggest that this simple approximation also holds for larger population sizes.

Simple and effective ultrasound needle guidance system.

In this paper, we describe our prototype of an ultrasound guidance system to address the need for an easy-to-use, cost-effective, and portable technology to improve ultrasound-guided procedures. The system consists of a lockable, articulating needle guide that attaches to an ultrasound probe and a user-interface that provides real-time visualization of the predicted needle trajectory overlaid on the ultrasound image. Our needle guide ensures proper needle alignment with the ultrasound imaging plane. Moreover, the calculated needle trajectory is superimposed on the real-time ultrasound image, eliminating the need for the practitioner to estimate the target trajectory, and thereby reducing injuries from needle readjustment. Finally, the guide is lockable to prevent needle deviation from the desired trajectory during insertion. This feature will also allow the practitioner to free one hand to complete simple tasks that usually require a second practitioner to perform. Overall, our system eliminates the experience required to develop the fine hand movement and dexterity needed for traditional ultrasound-guided procedures. The system has the potential to increase efficiency, safety, quality, and reduce costs for a wide range of ultrasound-guided procedures. Furthermore, in combination with portable ultrasound machines, this system will enable these procedures to be more easily performed by unskilled practitioners in non-ideal situations such as the battlefield and other disaster relief areas.