(Mis)perceptions of inequality

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.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.We are grateful to the Foundations of Human Behavior Initiative at Harvard University for financial support

Heterogeneity in background fitness acts as a suppressor of selection

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.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. Previous article in issueO.P.H. is grateful for fellowship support from Harvard's Department of Organismic and Evolutionary Biology. O.P.H. and M.A.N. are thankful for support from the Templeton Foundation. A.T. thanks the Max-Planck-Gesellschaft for generous funding

Budging Beliefs, Nudging Behaviour

This is the final version. Available on open access from Springer via the DOI in this record.Nudges have become a popular tool for behaviour change; but, some interventions fail to replicate, even when the identical, previously successful intervention is used. One cause of this problem is that people default to using some of or all of the previously-successful existing nudges for any problem – the “kitchen sink” approach. We argue that the success of an intervention depends on understanding people’s current behaviour and beliefs to ensure that any nudge will actually “budge” them from their current beliefs. We introduce the Beliefs-Barriers-Context (“BBC”) model, with three components: understanding beliefs, barriers, and context to change behaviour through a budge. Designing a budge has the goal of identifying the psychological mechanism that drives a target behaviour, focusing on the psychology of the target population before attempting to change that behaviour. In contrast to the “kitchen sink” approach, budges are best complemented with mechanism experiments to identify what undergirds behaviour change. Moving away from simply nudging behaviour to budging minds—by understanding beliefs, barriers and context—has the potential to inform both the successes and failures of behavioural interventions

Punishment does not promote cooperation under exploration dynamics when anti-social punishment is possible

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.It has been argued that punishment promotes the evolution of cooperation when mutation rates are high (i.e. when agents engage in ‘exploration dynamics’). Mutations maintain a steady supply of agents that punish free-riders, and thus free-riders are at a disadvantage. Recent experiments, however, have demonstrated that free-riders sometimes also pay to punish cooperators. Inspired by these empirical results, theoretical work has explored evolutionary dynamics where mutants are rare, and found that punishment does not promote the evolution of cooperation when this ‘anti-social punishment’ is allowed. Here we extend previous theory by studying the effect of anti-social punishment on the evolution of cooperation across higher mutation rates, and by studying voluntary as well as compulsory Public Goods Games. We find that for intermediate and high mutation rates, adding punishment does not promote cooperation in either compulsory or voluntary public goods games if anti-social punishment is possible. This is because mutations generate agents that punish cooperators just as frequently as agents that punish defectors, and these two effects cancel each other out. These results raise questions about the effectiveness of punishment for promoting cooperation when mutations are common, and highlight how decisions about which strategies to include in the strategy set can have profound effects on the resulting dynamics.O.P.H. is grateful to the department of Organismic and Evolutionary Biology at Harvard for fellowship support. Funding from the John Templeton Foundation is gratefully acknowledged

The role of inequity aversion in microloan defaults

This is the author accepted manuscript. The final version is available from CUP via the DOI in this recordMicrocredit—joint liability loans to the poorest of the poor—has been touted as a powerful approach for combatting global poverty. But sustainability varies dramatically across banks. Efforts to improve the sustainability of microcredit have assumed defaults are caused by free24 riding. Here, we point out that the response of other group members to delinquent groupmates also plays an important role in defaults. Even in the absence of any free-rider problem, some people will be unable to make their payments due to bad luck. It is other group members’ unwillingness to pitch in extra – due to, among other things, not wanting to have less than other group members – that leads to default. To support this argument, we utilize the Ultimatum Game (UG), a standard paradigm from behavioral economics for measuring one’s aversion to inequitable outcomes. First, we show that country-level variation in microloan default rates is strongly correlated (overall r = 0.81) with country-level UG rejection rates, but not free-riding measures. We then introduce a laboratory model “Microloan Game,” and present evidence that defaults arise from inequity averse individuals refusing to make up the difference when others fail to pay their fair share. This perspective suggests a suite of new approaches for combatting defaults that leverage findings on reducing UG rejections

Think global, act local: Preserving the global commons

This is the author accepted manuscript. The final version is available from Springer Nature via the DOI in this recordPreserving 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.This work was supported by Office of Naval Research grant N00014-16-1-2914 and by the John Templeton Foundation. The Program for Evolutionary Dynamics is supported in part by a gift from B Wu and Eric Larson

Cooperating with the future

This is the author accepted manuscript. The final version is available from Nature Publishing Group via the DOI in this record.Overexploitation of renewable resources today has a high cost on the welfare of future generations1,2,3,4,5. Unlike in other public goods games6,7,8,9, 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. Voting10,11,12,13,14,15 is effective for two reasons. First, it allows a majority of cooperators to restrain defectors. Second, it reassures conditional cooperators16 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.Financial support from the Department of Organismic and Evolutionary Biology at Harvard, the Harvard Office for Sustainability and the John Templeton Foundation is gratefully acknowledged

Generative AI enhances individual creativity but reduces the collective diversity of novel content

This is the final version. Available from American Association for the Advancement of Science via the DOI in this record. Data and materials availability: All data and code needed to replicate these analyses are available at Dryad: https://doi.org/10.5061/dryad.qfttdz0pm. All other data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials.Creativity is core to being human. Generative artificial intelligence (AI)—including powerful large language models (LLMs)—holds promise for humans to be more creative by offering new ideas, or less creative by anchoring on generative AI ideas. We study the causal impact of generative AI ideas on the production of short stories in an online experiment where some writers obtained story ideas from an LLM. We find that access to generative AI ideas causes stories to be evaluated as more creative, better written, and more enjoyable, especially among less creative writers. However, generative AI–enabled stories are more similar to each other than stories by humans alone. These results point to an increase in individual creativity at the risk of losing collective novelty. This dynamic resembles a social dilemma: With generative AI, writers are individually better off, but collectively a narrower scope of novel content is produced. Our results have implications for researchers, policy-makers, and practitioners interested in bolstering creativity.University of ExeterUniversity College, Londo

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

This is the author accepted manuscript. The final version is available from Springer Nature via the DOI in this recordSustaining large-scale public goods requires individuals to make environmentally friendly decisions today to benefit future generations. Recent research suggests that second-order normative beliefs are more powerful predictors of behaviour than first-order personal beliefs. 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

Invisible Inequality Leads to Punishing the Poor and Rewarding the Rich

This is the author accepted manuscript. The final version is available from Cambridge University Press via the DOI in this record.Four experiments examine how lack of awareness of inequality affect behaviour towards the rich and poor. In experiment 1, participants who became aware that wealthy individuals donated a smaller percentage of their income switched from rewarding the wealthy to rewarding the poor. In experiments 2 and 3, participants who played a public goods game— and were assigned incomes reflective of the U.S. income distribution either at random or on merit—punished the poor (for small absolute contributions) and rewarded the rich (for large absolute contributions) when incomes were unknown; when incomes were revealed, participants punished the rich (for the low percentage of income contributed) and rewarded the poor (for their high percentage). In experiment 4, participants provided with public education contributions for five New York school districts levied additional taxes on mostly poorer school districts when incomes were unknown, but targeted wealthier districts when incomes were revealed. These results shed light on how income transparency shapes preferences for equity and redistribution. We discuss implications for policy-makers