Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness

by Peter Godfrey-Smith

One possibility is that a chromatophore might sit on top of a light-sensitive cell, acting like a filter. That photoreceptor would then respond to colored light differently from a photoreceptor paired with a differently colored chromatophore. Another possibility was suggested to me by Lou Jost, an ecologist, orchid expert, and artist. He suggested that the act of changing colors might do the trick. Suppose some light-sensitive cells sit below a layer of many chromatophores. As chromatophores of different colors expanded and contracted, the light passing through them would be affected in different ways. If the animal kept track of which chromatophores were expanded, as well as how much light was reaching its sensors, it could know something about the color of incoming light. The animal would be like a cameraman exchanging one filter for another, as it went through its color changes. A monochrome sensor can detect color if the organism has filters of different colors and knows which ones are operating at each moment.