. We show here that this need not be the case. A simple image scoring mechanism where more than just one past action is … in groups where partners meet only once. The first model for which this has analytically been shown was the binary image … scoring mechanism, where one's reputation is only based on one's last action. But this mechanism is known to fail if errors in …

model (Sugden, 1986/2004) and the image-scoring model (Nowak and Sigmund, 1998a,b). Although there is evidence that the … case. I then suggest that the information needed by the image-scoring model, under reasonable assumptions, may be …