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Abstract:
Why does trust vary so substantially across countries? This paper presents a general equilibrium growth model in which heterogeneous agents transact and face a moral hazard problem. Agents may trust those with whom they transact, but they also have the opportunity to invest resources in verifying the truthfulness of claims made by transactors. We characterise the social, economic and institutional environments in which trust will be high, and show that low trust environments reduce the rate of investment. The predictions of the model are examined empirically for a cross-section of countries and have substantial support in the data.

Trust, Growth, Moral Hazard, Heterogeneity, Inequality, Discrimination, Uncertainty

Abstract:
Why does trust vary so substantially across countries? How does trust affect growth? This paper presents a general equilibrium growth model in which heterogeneous agents transact and face a moral hazard problem. Agents in this world may trust those with whom they transact, but they also have the opportunity to invest resources in verifying the truthfulness of claims made by transactors. We characterize the social, economic and institutional environments in which trust will be high and show that low trust environments reduce the rate of investment and thus the economy's growth rate. Further, we show that very low trust societies can be caught in a poverty trap. The predictions of the model are examined empirically for a cross-section of countries and have substantial support in the data. Trust is higher in more ethnically, socially and economically homogeneous societies and where legal and social mechanisms for constraining opportunism are better developed. High-trust societies, in turn, exhibit higher rates of investment and growth.

Abstract:
The traditional view in economics is that individuals respond to incentives, but absent strong incentives to the contrary selfishness prevails. Moreover, this "greed is good" approach is deemed "rational" behavior. Nevertheless, in daily interactions and in numerous laboratory studies, a high degree of cooperative behavior prevails - even among strangers. A possible explanation for the substantial amount of "irrational" behavior observed in markets (and elsewhere) is that humans are a highly social species and to an extent value what other humans think of them. This behavior can be termed trustworthiness - cooperating when someone places trust in us. I also present the cross-country evidence for environments that produce high or low trust. A number of recent experiments from my lab have demonstrated that the neuroactive hormone oxytocin facilitates trust between strangers, and appears to induce trustworthiness. In rodents, oxytocin has been associated with maternal bonding, pro-social behaviors, and in some species long-term pair bonds, but prior to the work reviewed here, the behavioral effects of oxytocin in humans had not been studied. This chapter discusses the neurobiology of positive social behaviors and how these are facilitated by oxytocin. My experiments show that positive social signals cause oxytocin to be released by the brain, producing an unconscious attachment to a stranger. I also discuss recent research that manipulates oxytocin levels, and functional brain imaging research on trust.

Trust, oxytocin, brain, fMRI, experiments

Abstract:
Zak & Knack (2001) demonstrate that interpersonal trust substantially impacts economic growth, and that sufficient interpersonal trust is necessary for economic development. To investigate the ability of policy-makers to affect trust levels, this paper builds a formal model characterizing public policies that can raise trust. The model is used to derive optimal funding for trust-raising policies when policy-makers seek to stimulate economic growth. Policies examined include those that increase freedom of association, build civic cultures, enhance contract enforcement, reduce income inequality, and raise educational levels. Testing the model's predictions, we find that only freedom, redistributive transfers, and education efficiently and robustly stimulate prosperity. They do this by strengthening the rule of law, reducing inequality, and by facilitating interpersonal understanding, all of which raise trust.

Trust, Growth, Policy, Education, Inequality

Abstract:
The purpose of this paper is to catalog some of the important findings from the fields of psychology and neurology, and to show potential implications for economics, with particular emphasis on financial markets. The blending of these fields is developing a new sub-field of neuroeconomics known as neurofinance.

Neuroeconomics, Neurofinance, Psychology, Finance

Abstract:
This book calls into question the commonly held view of the economy as being dominated by greed and selfishness. The cartoon of greed is good is nearly ubiquitous in Western countries, and is often more strongly accepted in less developed nations. Yet, this pervasive belief is inconsistent with the scrutiny of scholars ancient and modern. This book draws these findings together to focus on how morals and markets connect to each other. It integrates thought from social philosophers like Aristotle and Adam Smith with current research in behavioral biology and neuroeconomics. This book also asks why economists, business-people, journalists, and the general public continue to believe in greed as the sole driver of trade in markets. The contributors seek to remedy this misapprehension by marshalling evidence across a variety of literatures.

Abstract:
This chapter will survey neuroscientific research and discuss recent experiments from my lab on the physiologic basis for interpersonal decision-making to support the follow thesis: most people, most of the time, behave ethically, and that a set of shared values is essential to the functioning of modern economies. I call this "moral economics." Next, I will draw implications for law, institutional design, and public policy that follow from moral economics. What I would like to demonstrate is that values are a critical ingredient in producing the historically high living standards in many nations, and are a prerequisite to economic growth in the developing world.

Abstract:
Economic reform in China has created a small but fast-growing private sector that has spurred rapid productivity growth. Growth of the private sector is predicated upon continued labor movements away from state-run industries and into private firms. This paper presents a theory of labor market sectoral choice demonstrating that three factors determine private sector labor supply--the difference in wages between the state and private sectors, private sector wage risk and risk aversion. Estimation of the model using survey data provides strong support for the theory. We find that the riskiness of private sector earnings has a greater effect in discouraging workers from taking jobs in private firms than the wage premium has in attracting workers.

Abstract:
Recent biomedical research shows that roughly three-quarters of cognitive abilities are attributable to genetics and family environment. This paper presents a theory of growth in which human capital is determined by inheritable factors and family size. The distribution of income is shown to affect the number of births, with greater inequality raising the fertility rate and reducing output growth in the transitional dynamics. If human or physical stocks are sufficiently low, the model shows that an economy can be caught in a fertility-caused poverty trap, while countries with more resources will converge to a balanced growth path where the average rate of transmission of human capital from parents to children determines the long-run rate of output growth.

Abstract:
Human beings routinely help strangers at costs to themselves. Sometimes the help offered is generous - offering more than the other expects. The proximate mechanisms supporting generosity are not well-understood, but several lines of research suggest a role for empathy. In this study, participants were infused with 40 IU oxytocin (OT) or placebo and engaged in a blinded, one-shot decision on how to split a sum of money with a stranger that could be rejected. Those on OT were 80% more generous than those given a placebo. OT had no effect on a unilateral monetary transfer task dissociating generosity from altruism. OT and altruism together predicted almost half the interpersonal variation in generosity. Notably, OT had twofold larger impact on generosity compared to altruism. This indicates that generosity is associated with both altruism as well as an emotional identification with another person.

Altruism, Empathy, Generosity, Humans, Money, Oxytocin, Charity

Abstract:
This paper builds an age-structured model of human population genetics in which agents are endowed with a high-dimensional genome that determines their cognitive and physical characteristics. Young adults optimally search for a marriage partner, work for firms, consume goods, save for old age and, if married, decide how many children to have. Applying the fundamental genetic operators, children receive genetic material from their parents. An agent's human capital (productivity) is an aggregate of the received genetic endowment and environmental influences. Thus, the population of agents and the economy co-evolve. The model examines the impact of social and economic institutions on economic performance, including inequality in income and genetic attributes, the transition to an information economy, population bottlenecks, matchmaking, and love. We find that institutional factors significantly impact economic performance by affecting marriage, family size, and the intergenerational transmission of genes.

Abstract:
Recent findings in the biomedical literature have shown that roughly three-quarters of one's cognitive abilities are an endowment from one's parents. This paper develops an open economy theory of endogenous growth in which agents make fertility and migration choices which affect the rate of transmission of human capital from parents to children. The model produces both a poverty trap as well as convergence to a common balanced growth path. We characterize the factors that determine the rate of convergence to the balanced growth path by identifying the point at which the transitional dynamics end and balanced growth begins. The model shows that the migration of productive factors has quite different implications for developing and developed countries. Developing countries may undergo a temporary or permanent output contraction and a widening of the income distribution due to labor migration. Developed countries receiving migrants will have a temporary drop in wages for native agents, but will generally grow more rapidly due to migration. The model also shows that government efficiency affects both the rate of convergence to the balanced growth path and the rate of migration of productive factors.

Abstract:
Institutions can affect individual behavior both via their efficiency impact and via their risk reducing mechanisms. However there has been little study of the relative importance of these two channels in how individuals choose between simultaneously extant institutions. This paper presents a simple model of institutional choice in a labor market when there is a risk/reward trade-off, and tests the predictions of the theory. Using a novel empirical approach that adapts an ARCH-in-mean to cross-sectional survey data from China, we find that risk and risk aversion are strongly related to the choice of a labor market institution. Further, risk and risk aversion are quantitatively more important than the sectoral wage differential in explaining employment institution choices. Specifically, we find that wage risk has two orders of magnitude greater impact on labor market institutional choice than the wage difference, with a one standard deviation increase in earnings risk reducing the number of workers choosing jobs in the private (risky) sector by 22%.

Institutions, Risk, Labor Market, Risk Aversion

Abstract:
Adam Smith made a persuasive case that moral sentiments are the foundation of ethical behaviors in his 1759 The Theory of Moral Sentiments. This view is still controversial as philosophers debate the extent of human morality. One type of moral behavior, assisting a stranger, has been shown by economists to be quite common in the laboratory and outside it. This paper presents the Empathy-Generosity-Punishment model that reveals the criticality of moral sentiments in producing prosocial behaviors. The model's predictions are tested causally in three neuroeconomics experiments that directly intervene in the human brain to turn up and turn down moral sentiments. This approach provides direct evidence on the brain mechanisms the produce prosociality using a brain circuit called HOME (Human Oxytocin-Mediated Empathy). By characterizing the HOME circuit, I identify situations in which moral sentiments will be engaged or disengaged. Using this information, applications to health and welfare policies, organizational and institutional design, economic development, and happiness are presented.

Neuroeconomics, Law, morality, emotions, Adam Smith

Abstract:
This essay introduces a neurologically-informed formal model of collective action that reveals the role for empathy and distress in motivating costly helping behaviors. This model is based on a brain circuit that our lab has recently characterized called HOME (Human Oxytocin Mediated Empathy) System. We review how our studies have identified HOME and use this to draw implications for how collective action can be initiated, sustained, and revived.

Abstract:
The Rule of One-Third guaranteed wives a life interest in one-third of their husband's estate upon marital dissolution. We document the ubiquity of this legal construct and demonstrate that children's outcomes are imperiled absent a wife's residual claim on her husband's estate. Using ancient Roman law as an example, we argue that the patriarch, or paterfamilias, is the primary legal entity with an interest in creating and enforcing the Rule of One-Third. In a game-theoretic model, we show that the Rule of One-Third obtains when mothers and fathers are equally important at producing children's human capital, and when it is enforced by the paterfamilias or by modern legal institutions. The Rule of One-Third places the cost of marital dissolution on the household rather than society, and solves a contracting problem between the husband and wife when each is specialized in tasks the other cannot perform well.

Abstract:
The Rule of One-Third guaranteed wives one-third of their husband's estate upon marital dissolution through death or divorce. We document the historical ubiquity of this legal construct and show that without a wife's residual claim on her husband's estate, children's outcomes are imperiled. Using ancient Roman law as an example, we argue that the patriarch, or paterfamilias, is the main legal entity with an interest in creating and enforcing the Rule of One-Third. Then, in a game-theoretic model, we demonstrate that the Rule of One-Third obtains when mothers' and fathers' marginal impacts on their children's human capital are equal. We conclude that the Rule of One-Third arose in many societies because it places the cost of marital dissolution on the household rather than society and solves a contracting problem between the husband and wife when each is specialized in tasks the other cannot perform well.

Abstract:
The transition to market-oriented economies in Central and Eastern Europe and the former Soviet Union in the 1990s, like the Great Depression in the U.S. and Germany in the 1930s, generated sharp declines in real incomes and a corresponding drop in fertility. This is contrary to the robust negative relationship between income and fertility that has been extensively documented. This paper presents a theoretical model that explains the positive relationship between fertility and income. The model predicts that: i) the perceived level of subsistence consumption fundamentally determines whether fertility and income are positively or negatively related; ii) once incomes decline below a threshold, declining labor income causes fertility to fall; and iii) rising income inequality has a negative impact on fertility rates. Empirical tests using both aggregate and microeconomic data provide strong support for the predictions of the model. Our empirics predict that the perceived subsistence level is a statistically significant determinant of fertility and that the average country in our sample will remain in a Mathusian fertility regime for twenty more years.

Fertility, Subsistence Consumption

Abstract:
We analyze the dynamics of a simple growth model in which production occurs with a delay while new capital is installed (time-to-build). The time-to-build technology is shown to yield a system of functional (delay) differential equations with a unique steady state. We demonstrate that the steady state, though typically a saddle, may exhibit Hopf cycles on a measurable set of the parameter space. Furthermore, the optimal path to the steady state is oscillatory. A counter-example to the claim that intrinsically oscillatory on the central technical apparatus the mathematics of functional differential equations.

Abstract:
Is there a biological basis for morality? This talk will survey recent studies from my lab that are characterizing the role of oxytocin in producing a variety of moral behaviors. Using a neuroeconomics paradigm to measure virtue in vice in the laboratory, oxytocin is implicated in the virtues of trustworthiness, sacrifice, generosity, and empathy. Applications to law are also identified.

Abstract:
Trust pervades human societies. Trust is indispensable in friendship, love, families and organizations, and plays a key role in economic exchange and politics. In the absence of trust among trading partners, market transactions break down. In the absence of trust in a country's institutions and leaders, political legitimacy breaks down. Much recent evidence indicates that trust contributes to economic, political and social success. Little is known, however, about the biological basis of trust among humans. Here we show that intranasal administration of oxytocin, a neuropeptide that plays a key role in social attachment and affiliation in non-human mammals, causes a substantial increase in trust among humans, thereby greatly increasing the benefits from social interactions. We also show that the effect of oxytocin on trust is not due to a general increase in the readiness to bear risks. On the contrary, oxytocin specifically affects an individual's willingness to accept social risks arising through interpersonal interactions. These results concur with animal research suggesting an essential role for oxytocin as a biological basis of prosocial approach behaviour.

Trust, oxytocin, prosocial behavior

Abstract:
This paper introduces an emerging transdisciplinary field known as neuroeconomics. Neuroeconomics uses neuroscientific measurement techniques to investigate how decisions are made. First, I present a basic overview of neuroanatomy and explain how brain activity is measured. Then I survey findings from the neuroeconomics literature on acquiring rewards and avoiding losses, learning, choice under risk and ambiguity, delay of gratification, the role of emotions in decision-making, strategic decisions, and social decisions. I conclude by identifying new directions that neuroeconomics is taking, including applications to public policy and law.

Reward, Brain, Trust, Emotions, Strategy, Neuroimaging

Abstract:
Does the level of government debt affect living standards and if so, to what extent? We quantify the impact of the U.S. federal debt using an open economy overlapping generations model in which consumers have long but finite lifetimes. A demographic structure allows fiscal policy changes to have different effects on different agents, and reveals the linkages between public debt, output and international trade. We find that reducing the debt has relatively modest impacts on aggregates, while reducing government spending substantially raises U.S. incomes and welfare. Therefore, this paper contributes to the current debate regarding whether U.S. federal government budget surpluses should be used to retire government debt.

Debt, fiscal policy, overlapping generations, computable general equilibrium models