We assess the effect of the built environment on low-cost helping behavior toward neighbors. The setting is households in Shanghai, China that, due to rapid development, were involuntarily, i.e. as good as randomly, relocated to different building structures. Using a natural field experiment of misdelivered mail, we test the causal effect of spatial proximity and the built environment on helping behavior. Living one floor apart reduces the willingness to help a neighbor by 16 percentage points, similar to adding one more apartment per floor. Small spatial barriers can profoundly shape social interactions, and helping behavior, in urban settings.

People pay attention to the appearance of others, and personal characteristics can affect many types of decisions. We ask, is there informational value in a face in a situation where trust and reciprocity can increase earnings? We use a laboratory trust game experiment where subjects are unable to observe a counterpart, must observe a counterpart, or can pay to reveal a counterpart's photograph. Both senders and responders are willing to pay to observe the photos, and we show that behavior, earnings, and efficiency are affected. When subjects are “face to face,” efficiency is enhanced, and senders have higher earnings.

In the past several decades, the experimental method has lent deep insights into economics. One area that has contributed is the experimental study of children, where advances as varied as the evolution of human behaviors that shape markets and institutions to how early life influences shape later life outcomes, have been explored. We first develop a framework for economic preference measurement that provides a lens into how to interpret data from experiments with children. Next, we survey work that provides general empirical insights within our framework and provide a comprehensive summary of experimental methods used with children. Finally, we provide 10 tips for pulling off experiments with children, including factors such as taking into account child competencies, causal identification, and logistical issues related to recruitment and implementation. We envision the experimental study of children as a high-growth research area in the coming decades as social scientists begin to more fully appreciate that children are active participants in markets who (might) respond predictably to economic incentives.

The ultimatum game, by its all-or-nothing nature, makes it difficult to discern what kind of preferences may be generating choices. We explore a game that convexifies the decisions, allowing us a better look at the indifference curves of bargainers while maintaining the subgame-perfect equilibrium. We conclude that bargainers' preferences are convex and regular but not always monotonic. Money-maximization is the sole concern for about half of the subjects, while the other half reveal a preference for fairness. We also found, unexpectedly, the importance of risk aversion among money-maximizing proposers, which in turn generates significant bargaining power for fair-minded responders.

We investigate how skills developed when children are 3–5 years old drive schooling outcomes in middle childhood and adolescence. We find that skills map onto three distinct factors—cognitive skills, executive functions, and economic preferences. Importantly, each of the three factors predict later schooling outcomes. While early executive function skills and cognitive scores are linked to future behavioral patterns and other key student outcomes, economic preferences have an independent effect: children who are impatient in early childhood have more disciplinary referrals. Finally, random assignment to preschool impacts grades and disciplinary referrals through changes to cognitive skills and executive functions.