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On Vision

by Peter Lorden

What actually happens when we see? Just as the windows of a house are those of the house and not of a creature looking through them, so eyes are not “the windows of the soul” but of the skull. And to ask what is looking through them is simply to mislead ourselves, because the question implies another pair of eyes inside the skull.

For present purposes, all that we know of vision is that light passing through the lens of the eye projects an image on its retina and that this image – or an encoded version of it – is conveyed by the optic nerve to the visual centre of the brain. What happens there is a mystery.

Consider the case of an ophthalmologist who performs an operation enabling a patient gone blind to see again. Beyond his knowledge of optical mechanics, the doctor has no more idea of the perceptual process than you or I. Between the input to the optic nerve and the patient’s response there is a gap we cannot cross. The bridge is missing. It is as though the doctor’s physical knowledge were a road he travels along with confidence until the road suddenly drops off into darkness. And from the other side of that darkness – as the bandage is removed – he hears the patient crying, “I can see..!”

To suppose that the actual seeing is done by some inner self or soul or Descartian ‘little man’ residing in the brain is to raise more questions than it answers, for such a being would presumably have to have eyes of its own, and thus another being behind them; it entails an infinite recession of fictional entities, yielding no answer at all. Furthermore, all such notions of an inner seer tend to dissolve when we reflect upon the evolution of the eye. This marvelously delicate mechanism which now yields (we’re told) some 80% of our information in daily life began simply as a light-sensitive spot on the skin of a primitive organism. We can trace its development through such intermediate steps as the eye of the frog, which detects only a moving shadow. At what point does the alleged soul or inner seer enter this evolutionary stream? To the theologian who denies both evolution and the presence of a soul in other species, we can reply that the higher animals see very much as humans do. Why should the intervention of a soul be necessary to explain our vision and not theirs?

Whatever happens in the visual centre, however, must be very much like what happens when other kinds of sensory stimuli are processed by those areas of the brain devoted to them. We can safely assume this because we know that perception is sensation recognised. Sensation in itself – meaning the mechanical stimulus of a physical sense organ – has to be unconscious. From such varied phenomena as shock, anaesthesia and Freudian repression we know that organs may function perfectly without their excitation entering consciousness at all. Eyes don’t see any more than a camera does. Sensation is purely mechanical, its effect rising into perception only when recognition occurs. Nothing unrecognised can enter the sphere of awareness because to be aware of something is to recognise it. No matter how vague or slight or unfamiliar a perception may be, it is always a perception of something. Even if the subject has only flashes or light or a confused buzzing or a dull ache he can report that it’s that and not something else. And of a physical stimulus that seems new to us we can always say what it is like: that is, we can categorise it. In short, every perception is a response of the past to the present. Without the risen past there can be no present. Memory is therefore as essential to perception as it is to consciousness in general.

Memory may be defined as the capacity of a substance to be altered by experience. This applies to any substance, in the sense that a dirt road remembers or records through the ruts on its surface the traffic it has borne. But an intelligent substance is altered by experience in such a way as to improve its response to similar experience thereafter. The process is certainly not infallible – as witness how often we tend to repeat our mistakes! – but is nevertheless an essential characteristic of life. As distinct from the inanimate, where change is purely passive, or reaction as mechanical as that of a steel spring, even the simplest organism has the capacity to be altered in a self helping manner. In other words, living things learn, because the basis of all lifeactivity is what may be called sensible reaction.

‘Sensible’ is used here in two meanings, firstly that the reaction is to some stimulus from sense organs, and secondly that it makes sense in terms of the creature’s self-interest. And sensible reaction in turn arises from the fact that the most fundamental characteristic of all life is need. A rock in a glass case may last forever unchanged because a rock doesn’t need anything, but the existence of a living form is forever contingent, forever at risk. It can persist only by turning other things into itself – food, water, air – in a perpetual process of transformation. Need, therefore, acts as a kind of vacuum continually pulling us onward, pulling us into action aimed at satisfying our various requirements for survival. Failure brings pain while success brings pleasure, these two being the great masters of all mortality, the twin guides to conduct in all forms of life. (And clearly it is pain which comes first; pain is the goad without which we should do nothing at all. Because a babe-in-arms cannot conceive a goal or the prospect of pleasure, it cannot be that which stirs him to action. It is the pain of hunger or some other discomfort which sets him kicking or crying, and his reward is the cessation of it.)

That an infant’s activity – as all parents know to their cost – very soon switches from the avoidance of pain to the pursuit of virtually unlimited goodies does not alter the fact that need is the primary spur. And the learning process so essential to the resulting activity has to be cumulative. Whereas impressions on a dirt road may be obliterated by later ones, memory in a life form has to be lifelong, a continuous record to which every fresh stimulus may be referred for evaluation in terms of the creature’s welfare. And as T.S.Eliot remarked in another context, the record is continuously evolving, the past being literally changed as present experience alters our perspective on it. This understood, it becomes clear that memory is not merely something that we have as we have other things but much more truly what we are.

Whether our memory of previous images and of their meaning for us is contained in the visual centre or in some other part of the brain communicating with it, we may be sure that a “matching” process is an essential component of seeing. If anything can be said to look through the eyes, then, it is certainly not some homunculus staring at a repetition of the retinal image but rather memory itself – the living past responding to the present.

Peter Lorden is a part-time philosopher who lives in Canada.