Figure 2. Comparison of Information Rates in R1–6 Photoreceptors from Four Dipteran Species.

Information rates (mean ± standard error of the mean) are measured from the response to a randomly modulated light of mean contrast 0.32, presented at five background (average) light levels to: S. carnaria (blue), C. vicina (red), D. virilis (green), and D. melanogaster (black). Each adapting light background was converted to effective photons s⁻¹ to allow the photoreceptors to be compared under equivalent conditions.