Ziqi Lu

How does repeated exposure to correlated information affect beliefs and decisions? In a field experiment on Weibo, we exposed Chinese college students to redundant negative posts about civil service jobs. Relative to the control group, treated students held views that were 0.16 standard deviations more negative and were 11% less likely to register for civil service exams. A supplementary online experiment produces similar findings and shows that attention moderates the effect. The results demonstrate that correlation neglect can influence consequential choices outside the laboratory.

Why can cooperation extend beyond close communities even as social ties weaken? We develop a repeated prisoner’s dilemma with voluntary separation in which the payoff from leaving a relationship fluctuates over time. Greater relational volatility destabilizes close partnerships but can prolong interactions between strangers, making sustainable cooperation less dependent on social distance. This generates a behavioral form of universalism without changing preferences. Yet this universalism is “thin”: cooperation can expand across social boundaries while becoming harder to sustain when it entails high individual costs. With endogenous relationship formation, individuals seek more socially distant partners, increasing the prevalence of weak ties. When third-party enforcement is available, volatility expands the use of formal contracts, including within close relationships previously sustained without them. The model connects the weakening of close communities, the expansion of cooperation among strangers, and the spread of contracting through a common change in the conditions sustaining repeated interaction.

We link 5,171 firms identified in bribery cases to 10.8 million Chinese public procurement contracts to study the value and pricing of procurement access. Procurement gains persist for about three years, including among firms with only one recorded bribery year, and are concentrated among firms that paid for procurement-related purposes. Larger firms and firms in more competitive industries obtain greater gains, but these differences are only weakly reflected in recorded payments. Instead, bribe amounts vary substantially with recipients’ locality and their departments’ administrative level. These findings suggest that bribery purchases durable, purpose-specific access at prices that are only coarsely differentiated across firms. In a financial subsample of about 1,000 firms, we find no detectable improvement in returns on assets or equity following bribery.

How does mobility affect cooperation when people can leave their relationships? I develop a repeated prisoner’s dilemma with voluntary separation. Greater voluntary mobility supports more unconditional cooperation, particularly among patient players, but also allows defectors to escape future punishment, making its effect on conditional cooperation ambiguous. Involuntary mobility always weakens cooperation. A meta-analysis of twelve prisoner’s dilemma experiments finds that voluntary mobility increases cooperation while weakening reciprocity. Evidence from the World Values Survey and Gallup World Poll is also consistent with the model’s predictions. The results distinguish the effects of opportunities to leave from those of involuntary disruption.

We study how clan culture shapes innovation, economic development, and income inequality. A growth model incorporating clan culture predicts higher asset prices, greater investment in research and development, and a smaller gap between capital and labor incomes. Using genealogical records to measure changes in local clan culture in China from 2004 to 2020, we find that stronger clan culture predicts higher local income and lower inequality. The empirical analysis combines a shift-share instrumental-variable approach with spatial models and finds substantial spillovers across locations. The paper connects clan-based social organization to innovation and the distribution of income.