2024-12-2920242199-677610.1007/s40881-023-00153-3https://doi.org/10.1007/s40881-023-00153-3https://hdl.handle.net/20.500.14288/22763This paper examines cooperation and punishment in a public goods game in Istanbul. Unlike prior within-subject designs, we use a between-subject design with separate no-punishment and punishment conditions. This approach reveals that punishment significantly increases contributions, demonstrating the detrimental effect of having prior experience without sanctions. We highlight two critical factors-heterogeneous initial contributions across groups and how subjects update their contributions based on prior contributions and received punishment. An agent-based model verifies that the interaction between these two factors leads to a strong persistence of contributions over time. Analysis of related data from comparable cities shows similar patterns, suggesting our findings likely generalize if using a between-subject design. We conclude that overlooking within-group heterogeneity biases cross-society comparisons and subsequent policy implications.EconomicsJournal article2199-67841137243100001Q240894