article published yes Laura Schmid author 38B437DE-F248-11E8-B48F-1D18A9856A870000-0002-6978-7329 Pouya Shati author Christian Hilbe author Krishnendu Chatterjee author 2E5DCA20-F248-11E8-B48F-1D18A9856A870000-0002-4561-241X GradSch department KrCh department Formal Methods for Stochastic Models: Algorithms and Applications project Formal methods for the design and analysis of complex systems project Indirect reciprocity is a mechanism for the evolution of cooperation based on social norms. This mechanism requires that individuals in a population observe and judge each other’s behaviors. Individuals with a good reputation are more likely to receive help from others. Previous work suggests that indirect reciprocity is only effective when all relevant information is reliable and publicly available. Otherwise, individuals may disagree on how to assess others, even if they all apply the same social norm. Such disagreements can lead to a breakdown of cooperation. Here we explore whether the predominantly studied ‘leading eight’ social norms of indirect reciprocity can be made more robust by equipping them with an element of generosity. To this end, we distinguish between two kinds of generosity. According to assessment generosity, individuals occasionally assign a good reputation to group members who would usually be regarded as bad. According to action generosity, individuals occasionally cooperate with group members with whom they would usually defect. Using individual-based simulations, we show that the two kinds of generosity have a very different effect on the resulting reputation dynamics. Assessment generosity tends to add to the overall noise and allows defectors to invade. In contrast, a limited amount of action generosity can be beneficial in a few cases. However, even when action generosity is beneficial, the respective simulations do not result in full cooperation. Our results suggest that while generosity can favor cooperation when individuals use the most simple strategies of reciprocity, it is disadvantageous when individuals use more complex social norms. https://research-explorer.ista.ac.at/download/9997/10006/2021_ScientificReports_Schmid.pdf application/pdfno https://creativecommons.org/licenses/by/4.0/ Springer Nature2021 eng Multidisciplinary 2045-2322 34465830 00069240640001810.1038/s41598-021-96932-1 111 https://research-explorer.ista.ac.at/record/10293 Schmid, Laura, et al. “The Evolution of Indirect Reciprocity under Action and Assessment Generosity.” <i>Scientific Reports</i>, vol. 11, no. 1, 17443, Springer Nature, 2021, doi:<a href="https://doi.org/10.1038/s41598-021-96932-1">10.1038/s41598-021-96932-1</a>. L. Schmid, P. Shati, C. Hilbe, K. Chatterjee, Scientific Reports 11 (2021). L. Schmid, P. Shati, C. Hilbe, and K. Chatterjee, “The evolution of indirect reciprocity under action and assessment generosity,” <i>Scientific Reports</i>, vol. 11, no. 1. Springer Nature, 2021. Schmid L, Shati P, Hilbe C, Chatterjee K. 2021. The evolution of indirect reciprocity under action and assessment generosity. Scientific Reports. 11(1), 17443. Schmid, Laura, Pouya Shati, Christian Hilbe, and Krishnendu Chatterjee. “The Evolution of Indirect Reciprocity under Action and Assessment Generosity.” <i>Scientific Reports</i>. Springer Nature, 2021. <a href="https://doi.org/10.1038/s41598-021-96932-1">https://doi.org/10.1038/s41598-021-96932-1</a>. Schmid, L., Shati, P., Hilbe, C., &#38; Chatterjee, K. (2021). The evolution of indirect reciprocity under action and assessment generosity. <i>Scientific Reports</i>. Springer Nature. <a href="https://doi.org/10.1038/s41598-021-96932-1">https://doi.org/10.1038/s41598-021-96932-1</a> Schmid L, Shati P, Hilbe C, Chatterjee K. The evolution of indirect reciprocity under action and assessment generosity. <i>Scientific Reports</i>. 2021;11(1). doi:<a href="https://doi.org/10.1038/s41598-021-96932-1">10.1038/s41598-021-96932-1</a> 99972021-09-11T16:22:02Z2026-06-15T22:30:42Z