File:Cooperation-Norms-and-Revolutions-A-Unified-Game-Theoretical-Approach-pone.0012530.s002.ogv

English: Same as Movie S1, but while interactions between both populations are considered, self-interactions are neglected (ba = 0 = ca, Ba = B, Ca = C). The contrast to Movie S1 is pronounced: In the snowdrift game (first half of the movie), everybody is either cooperative or non-cooperative in both populations now, corresponding to the stable fix points at (0,0) and (1,1) (see black circles). In contrast, in the stag hunt game (second half of the movie), the evolutionary equilibria are located at (p, q) = (1, 0) and (p, q) = (0, 1). p = 1 means that 100% of the individuals in population 1 show behavior 1, while q = 0 implies that 0% of the individuals in in population 2 show behavior 2 (i.e. all of them show behavior 1 as well). Therefore, we find the establishment of a commonly shared behavior (the formation of a behavioral norm).