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What is "seeing"?
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‘The eye and brain are not like a fax machine,
nor are there little people looking at the
images coming in’

– Torsten Wiesel

EYEThe puzzle of seeing
by G. Sarcone

Our brain is an artist that paints the reality that surrounds us. It transforms energy into color; links distances, movement and form to create reality in 3D; interprets visual stimuli and compares them to memories... and sometimes, it makes mistakes!

  Are the eyes an open door to the world, as poets say? Well, honestly, not really. The fact is, we see the world through a pair of tiny peepholes, the pupils of our eyes. Our brain functions as a highly creative ‘camera obscura’. The brain elaborates the visual stimuli we receive, transforming them into true artworks.
  The German poet Novalis said that the eye is a ‘superficial’ organ. That is indeed partly true. I will even add that it is an external organ: the eye with which we see the world is a part of the world itself. As soon as we open the eye, whup, the world pops in it!
  The eye is a humble and silent organ. It cannot ‘see’ itself, and is itself unnoticed in use. Moreover, unlike a camera, the eye ‘creates’ a field of vision without real edges. That seems paradoxical at first glance, that our field of vision is limited but does not have boundaries... There are no ‘blank’ zones outside of our visual field. Our brain simply cancels out those edges with a smooth fade-out effect.

The way we see and the way animals see
how the eye sees
Light from a scene passes through the pupil and strikes the eye's retina where it is reproduced upside-down.
how the brain sees
Here is how our brain visually 'translate' the perceptive stimuli from the eye.
how a color blind sees the scene
Some animals see differently than we do. Cats are red/green color blind, and only perceive the blues and yellows of the landscape.
how a bird sees the scene
Seabirds' photoreceptors contain yellow oil droplets which help polarize light and improve distance vision, especially in hazy conditions.
how a bull sees the scene
Bulls have few retinal cones, and as a result, they have no color vision. Also, their vision is much less acute than ours.
how a bee sees the scene
Bees and butterflies can see colors that we can't see. Their range of color vision extends into the ultraviolet.

  In English, there are two essential families of words that we use to express the faculty and the act of seeing: 1) ‘sight’, ‘see’, and 2) ‘vision’, ‘view’. Looking at these words etymologically, it seems most probable that they originally came from words that meant, respectively, “to follow something with the eyes” (from the Indo-European *seqw-) and “to have learned” (from the Indo-European *weid-). This suggests that, for our ancestors, an image was something to shape with the eyes (follow with the eye), a form of information taken from the real world (learning through visual perception).
  Unfortunately (or fortunately?), seeing isn’t some kind of direct perception of reality. Atcually, our bairns are cnostanlty itnerperting, corrceting and gviing srtuctrues to the viusal ipnut form our eeys (see footnote further below). If this were not the case, we wouldn’t see any colors, and we would probably see the world upside down! We would also notice in our visual field a very large dot, called the blind spot, where the optical nerve enters the eye.
  Moreover, vision isn’t an innate process at all. It depends to a large extent on ability acquired through a long and laborious undertaking. We take the concept of vision for granted, but a person who is blind from birth who later in life gains the sense of sight takes many years to learn how to understand and organize the things that he now perceives.
brain and vision  The ability to see is a process far from banal, and far from being passive. When we look at a panorama, its colors take around 30 milliseconds to arrive at the ‘visual cortex’ within the posterior lobes of our brain (also known as ‘striate cortex’ or ‘V1’). The shapes of the scene, and the sensation of the distances – which involve depth and motion – are perceived shortly after, at approximately 70 milliseconds. During these tiny slices of time, the brain filters, analyzes, and interprets the various pieces of the visual puzzle, trying to assemble them into a coherent image. In other words, it is crafting the best and most useful scene possible from the raw image data that our eyes present to us.

  Visual impairments tend to increase with age. As vision tends to blur,
contact lenses or glasses help improve eyesight. But sometimes visual deficiencies pass unnoticed, or are even not preventable or correctable, like colorblindness.

  I’ve always been fascinated and impressed by how people with partial or total visual sensory deficiencies interact with the world. We cannot talk about visual perception or optical illusions without mentioning the other side of the coin... To understand how these people ‘see’ without sight is to understand just how important our sense of sight is (sometimes we don’t do it justice or give it the importance it deserves) and how it collaborates and integrates with the other sense organs.
  Have you ever asked yourself what it is, when we see, walk, speak, feel and touch all at the same time, that links our sight with the sense of touch or hearing? The reality is we actually see very little: only that on which we are concentrating, or which we find important. Man without the crutches of the other sense organs would truly be lost, because it is they which permit us, subconsciously, to go about our everyday lives. An experiment demonstrated how at times we are really ‘blind’ in the truest sense of the word. In this famous experiment on ‘inattentional blindness’, performed in 1999, Daniel Simons and Christopher Chabris asked people to watch a video clip and count the number of times one of two teams of basketball players took possession of the ball. Many people (around 40 percent) didn’t notice at all a man in a gorilla suit entering stage right, doing a jig in the centre of the screen and then leaving, stage left. The clip demonstrated how we don’t see what we don’t pay attention to, even when it’s in front of our eyes!

*Most probably your brain has automatically corrected the sentence in “actually, our brains are constantly interpreting, correcting and giving structure to the visual input from our eyes”. It’s amazing, isn’t it?

        arrow What is an Optical illusion?

Creative Commons License
'What is seeing?' by G. Sarcone is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.


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