Simulation results for a model fly eye of size 30 × 50 obtained via the general response function of our model (Eq 6).

The parameter α quantifies the relative importance of stochastic decisions. In: (a) α = 1. This models a perfect Doli fly, where there are no mistakes; (b) α = 0. This models Drosophila, where the two colors are randomly distributed, with a bias towards the green; (c) α = 1. This models a Doli fly a perturbed column (eighth from right). Notice that the perturbations propagate leftward to the end, giving rise to a domain with a discernible boundary. (d) α = 0.7. The parameters ϵ (local speckle correlation coefficient) = 0.95, and were chosen with a view to match, at least qualitatively, the patterning of the intermediate, partially organized Chrysosoma sp. shown in Fig 1d.