Extended Data Fig. 1: ‘Look twice, forgive once’ is stable and facilitates cooperative outcomes regardless of the social norm.

We show the dynamics between ALLC, ALLD, and a discriminator strategy using M = 1 or M = 2. The classical DISC (M = 1) is unstable for all norms, and the cooperative outcomes for scoring and simple-standing are vulnerable to invasion by ALLD. When DISC_q,M uses M = 2 observations and is strict (q = 2/2), the outcomes of the dynamics are worse than with a single observation. But when DISC_q,M is tolerant (q = 1/2), it is stable regardless of the social norm. The rate of cooperation at the ‘look twice, forgive once’ equilibrium is > 99.8% for all norms. For all panels, the benefit-to-cost ratio is b/c = 5, with error rates of assessment and execution α = 0.02 and ε = 0.02, respectively.