Comment 16 by ARL

Remember that, from rather cruel experiments with cats, covering up a perfectly good eye from birth will cause neuroplastic changes such that the axons which would have referred to receptive fields at the covered-up retina are diverted for use at the uncovered retina. Once this has occurred, it is irreversible. Uncover the eye, and it will never see. Use it or lose it.

Dear Richard,

ARL is correct. I suggest you read David Hubel's book. It's downloadable.

Having read the book, my guess is that a person born colour blind would not have the neural machinery for colour vision, but it would be a fascinating experiment.

Currently electrode arrays are being developed that can be implanted into the brain and connected to a camera system. I think the current limitations are the number of electrodes (64*64?) and the lack of a permanent connection. The electrodes are neurophobic rather neurophylic.

I would be fascinated to see what would happen if one of these was planted into V1 of a colour blind person, and the array connected to a trichromatic camera. Would adult neuro-plasticity learn to see colour, or would it be too late?

On the more general question of qualia, and inter-species qualia, I don't think philosophical musings help. I take the pragmatic approach of considering computer and robotic systems.

From the computational viewpoint all animals need algorithms (that work on neural hardware) to make sense of noisy sensory data. So a bat has to extract the echo-features that are common to moths, and an ape has to extract the colour-features that are common to ripe fruit. Given the common mammalian heritage, I am sure the neural circuitry is the same.

If you have a few months to devote to it, I recommend the books of Prof. Edmund T. Rolls for an undergrad introduction to computational neuroscience. I also found Prof. Shimon Edelman's "Representaion and Recognition in Vision" useful. I am sure Dan Dennett is familiar with both of these authors, and can steer you.