When I was a little boy I thought that vision was like a kind of projector, casting images from the outside world up into my brain.
As I got a little older I thought the eye was like a prism, which would capture the outside view and transmit it upside down onto the back of my brain, then my brain would flip the image back the right way up somehow.
Once I learned more about it I discovered that neither of those explanations are even remotely correct. In fact, (of course), light doesn’t pass through our eyes at all so they are not in the slightest like camera lenses, or prisms. What happens is that light stimulates special cells which line the insides of our eyeballs, and those signals are converted into electric/chemical signals which are sent through nerve cells to the “visual cortex” at the back of the brain – yes the back of the brain! Isn’t it odd that the back of the brain is the bit we use to see with?!
For a while I pretty much left it at that. But then as I learned more I discovered that vision is a MUCH more creative process than I’d considered so far. Not only is there a patch inside the eye which has no specialised cells for responding to light at all – in other words there is a “blind spot” in each eyeball which is incapable of seeing anything, but the visual cortex isn’t even a single part of the brain.
In fact, nobody has managed to completely map out just how our brains created the experience of seeing. The visual cortex is now considered in six separate areas of the each hemisphere (named V1 – V6) – that is 6 areas for each hemisphere, or 12 separate areas altogether to create our experience of a seamless image with no blind spots or missing bits. Some of those parts respond to movement, some to colour, some to shapes, some are wired to perception and some to actions……really, it’s too complex so far for us to fully grasp.
So, here’s what surprises me – each eyeball has a bit in it that doesn’t create the images we see – we call that bit the “blind spot” and it’s where the nerve cells which lead into the brain gather together at the back of the eye. Then each eye sends its signals to a complex of six different areas of the brain.
And somehow, we weave together all those stimuli, and all those signals and computations to instantaneously create whole, seamless images. Amazing! Really, it’s astonishing.
So what do you think of these sculptures which were placed near to the town hall in Marseille?