Can chromatic aberration enable color vision in natural environments?

Stubbs and Stubbs present a novel visual mechanism based on chromatic aberration that might allow animals with only one spectral photoreceptor-type to perceive color (1) (see ref. 1 for details about their mechanism). The authors chose cephalopods to showcase their hypothesis and claim that discrepancies between earlier (2, 3) and recent (4, 5) negative behavioral color vision tests in cephalopods can be explained by their (1) mechanism. Although the Stubbs and Stubbs mechanism works in theory, we identified several factors that would decrease the utility of the suggested signal, given the visual ecology of cephalopods. The strength of the signal depends on how saturated the color of the object is. For the eye to quickly find the focal length that results in the best focus, the …