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

by Peter Godfrey-Smith

It’s one way of being wired up, and some animals do not integrate their experience nearly as much as we do. For example, in many animals the eyes are on each side of the head, not the front. The eyes then have separate visual fields, either largely or entirely, and each connects just to one side of the brain. In such an animal it is easy for scientists to control what each side is exposed to, by masking one eye. Then we can ask a question that might seem to have an obvious answer: If we show something to only one side of the brain, does the other side get the information too? We are not looking at damaged or altered animals here, so the two sides of the brain have all their natural connections. One would think that the information should get across. Why should evolution set things up so that only half the animal knows what has been seen? But when this question was studied in pigeons, it turned out that the information was not being passed across. The pigeons were trained to do a simple task with one eye masked, then each pigeon was tested on the same task while being forced to use the other eye. In a study using nine birds, eight of them did not show any “inter-ocular transfer” at all. What seemed to be a skill learned by the whole bird was in fact available to only half the bird; the other half had no idea.