We all have been through the biology class back in school when they taught us how we “see”. We have in fact drawn the two rays of light that create an upside-down image on the retina and the brain somehow correcting the orientation to enable us to see it correctly.
Nothing can be further from the truth.
Vision in fact is a complex process, and maybe this is why a third of the entire cereal cortex is engaged with vision.
Rods help us see in dim conditions and cones divide the world into three colors – red, green and blue. The eyes send a hundred billion signals to the brain every second. But all this is just information. The brain has to make sense of it, in order for us to “see”.
By the way, this information takes around one-fifth of a second to travel through the optic nerve to the brain. While this may not sound a lot, it is too long for the requirement, which may be instantaneous in some cases ( avoid falling or an accident for instance).
And so that the brain does, is fill in information for you. It forecasts what the world is like a fifth of a second from now, and that is what it presents to us as the present. This is why sight is continuous, and not in spurts a fifth of a second apart. Which would mean that we would see the world as continuous bursts of images, rather than a movie.
V.S. Ramachandran, in his book, “The Tell-Tale Brain”, describes sight in great detail. You should read it when you get a chance. Basically, while the process of sight is still being researched, the premise is that what we “see” is not usually what is out there. What we see is what the brain shows us, duly colored with color, perceptions and judgements based on our experiences.
That’s what you get for trusting an actor sitting in a perpetually dark room, being fed through nerve impulses and making sense of the whole thing to show you a movie. Ironically, the actor will never get to “see” what he shows you. Of course, the actor is the brain.
Goes to show that what you see, hear, touch, taste or smell, may not be what I experience. For instance, how red is red? I may see a different red, and you a different red. We don’t know for sure if they are exactly the same, since there is no objective way to compare. You just see a universally acknowledged approximation.
Gives a new meaning to the phrase ” I only believe what I see”, isn’t it?
Err…SEE you tomorrow!