readjustment. They need to gain experience of spatial relationships in order to interpret the visual information now entering their brain. Literally they have difficulty in understanding where one object ends and another object begins!
An astonishing, but ultimately sad example of someone who re-gained his sight after some 45 years of blindness can be read about in “An Anthropologist on Mars”(Vintage books, 1995) or go to http://enterprise.is.tcu.edu~bplate/relcult files/sacks.htm
Here are a few extracts of this case history about a patient called Virgil, who, after having cataracts removed, finds himself in a strange world. He had been born with normal sight, but lost it in childhood.
…(he) told me later in this first moment he had no idea what he was seeing. There was light, there was movement, there was colour, all mixed up, all meaningless, a blur. Then out of the blur came a voice that said, “Well?” Then, and only then, he said, did he finally realize that this chaos of light and shadow was a face – and, indeed, the face of his surgeon.
…The rest of us, born sighted, can scarcely imagine such confusion. For we, born with a full compliment of senses, and correlating these, one with the other, create a sight world from the start, a world of visual objects and concepts and meanings. When we open our eyes each morning, it is upon a world we have spent a lifetime learning to see. We are not given the world: we make our world through incessant experience, categorization, memory, and reconnection. But when Virgil opened his eyes, after being blind for forty-five years – having had little more than an infant’s visual experience, and this long forgotten – there were no visual memories to support a perception; there was no world of experience and meaning awaiting him. He saw, but what he saw had no coherence. His retina and optic nerve were active, transmitting impulses, but his brain could make no sense of them; he was, as neurologists say, agnostic.
Further problems became apparent: he would pick up details incessantly – an angle, an edge a colour, a movement – but would not be able to synthesize them, to form a complex perception at a glance. For example a cat, visually was puzzling: he would see a paw, the nose, the tail, an ear, but could not see all of them together, see the cat as a whole.
…His wife, Amy, had commented in her journal on how even the most obvious connections – visually and logically obvious – had to be learned. Thus, she told us, a few days after the operation “ he said that trees didn’t look like anything on earth,” but in her entry for October 21, a month after the operation, she noted, “ Virgil finally put a tree together – he now knows that the trunk and leaves go together to form a complete unit.” And on another occasion: “Skyscrapers are strange, (he) cannot understand how they stay up without collapsing.”
… This first month then, saw a systematic, by sight and touch, of all the smaller things in the house: fruit, vegetables, bottles, cutlery, flowers – turning them round and round, holding them close to him, then at arm’s length, trying to synthesize their varying appearances into a sense of unitary objectivity.
…Brain systems in all animals may respond to overwhelming stimulation, or stimulation past a critical point, with a sudden shutdown. Such reactions have nothing to do with the individual or his motives. They are purely local and physiological and can occur even in isolated slices of cerebral cortex: they are a biological defense against neural overload.
The brain has to learn how to interpret visual data. As Virgil in the above account took a month to realize that leaves and the trunk of a tree are part of the same object, this adds considerable weight to the argument that seeing is nothing to do with perception and therefore animal perceptions of the same visual data may well be dimensionally lower to that of humans. Here’s another example of a seventeen year-old youth recovering from a cataract operation from the magazine Sleptz in 1912.
In the same way, human perception of visual data may well be totally bereft of objective reality! We have all experienced a momentary lapse in our ability to interpret what we are looking at. Although it happens only rarely, we must admit that our incredibly agile brains can be fooled when it comes to analyzing spatial relationships. The obvious examples are optical illusions, for example Escher’s “impossible” drawing of a never-ending waterfall. Even when we know that we are looking