Figure 3.

‘Pseudo-relatedness' of individual 2 to individual 1, (blue), and of individual 1 to individual 2, (red), given a fixed total quantity of resources (x₁ + x₂ = 2), as one varies the fraction of those resources available to individual 1 rather than to individual 2. In the top panel, both place equal value on the public good (a₁ = a₂ = 0.6), whereas in the bottom panel, individual 1 places less value on the public good than does player 2 (a₁ = 0.4, a₂ = 0.8). Vertical grey lines demarcate zones that yield qualitatively different outcomes.