Fig 2. Strategies of image scoring and partner choice.

Strategy mixes with pure image scoring with random assignment (IS); incorporating phenotypic defectors (PD); and with partner choice (PC). Strategies are labelled as IR[k] where k is the strategy threshold. Thus k = -1 denoted individuals that cooperated unconditionally; k = 0 strategists cooperated provided their partner had never played or had cooperated; k = 1 strategists cooperated provided the partner had cooperated; and k = 2 strategists never cooperated. Proportions are shown as means over 10 simulations of within simulation means calculated across 10,000 generations.