The Job of Vision

The Vision System

When I give a speech about blindness, I ask the audience what vision does; what is the job of vision? Another way to ask the same question is to inquire what is lost when a person becomes blind.

Usually the first answer I get is that vision helps us identify the world, who we are seeing (Bill) or what we are looking at (a chair, a word, a falling star). Sometimes groups of sighted persons answer that vision helps us move around.

"Yes," I tell the audience, "Vision is an identification system and it is a navigation system, but it is much more than that. Years of working with blind children has helped me see how vision is involved in the total performance of the human body." We need to understand this broad statement because understanding the roles vision plays helps us clarify the adaptations that blind students need to function in a sighted world. Let's look at the obvious roles first.

Identification

Vision is a pattern recognition system. It learns to detect repeating patterns that have value for survival. Faces are important, body shapes, the letters that make words, the words that make paragraphs; all have features that stand out against the background. Our language is involved in the naming of these patterns. Higher level processing endows patterns with meaning, links patterns together in associations, and connects emotions with patterns. Mental concepts are created from the raw stuff of elementary visual patterns.

Navigation

Vision is a magnificent navigational system. It can operate in a subconscious mode, or it can consciously map the spatial layout of a room. We can daydream, or solve problems in our minds, all the while we are walking down a hallway or sidewalk, giving hardly a thought about straying onto the grass or walking headlong into a wall. We automatically flow through doorways, around obstacles, going from point A to point B without unnecessary side trips, without tripping, and without having to stop and ask for directions every few feet. Our navigation is so automatic and unconscious that few people even think to list navigation as a major job of the vision system.

Gait

The gait of sighted children (the balance, rhythm, speed, arm and leg swing patterns) is partially modeled on the movement style of role models; parents, and the rest of the walking world. Blind children, however, cannot visually model the walking pattern of those around them; they do not necessarily walk with the same heel-down-first, arm swinging, legs-close-together gait. They have a walking pattern that is more reactive, at the ready. This is because vision is a long range detector, giving early warning of approaching objects. The sighted have plenty of time to react. Not so for many blind kids. To adjust to the dangers of impending collision they often spread their stance outward and walk with their center of gravity back on their heels (some blind children do just the opposite of this, dropping their head forward, swinging the center of gravity forward, causing them to walk flat footed and to shuffle through space). Part of the job of the orientation and mobility specialist is to assess gait patterns and help model culturally acceptable (visual) patterns of walking, running, jogging, even standing.

Balance

Vision is neurologically linked to the body's balancing system. There are direct brain connections between the vestibular (balancing) system of the inner ear and the vision system. In some disease states, when the middle ear is destroyed, the only sense that can keep victims upright is vision. If the eyes are closed, the affected individual falls down. The loss of vision is the loss of a powerful balancing system; blind children may be less stable than their sighted peers, especially when blindness is congenital, and especially during early stages of development.

Posture and Gesturing

Vision helps sighted children model postural behavior. Every culture has acceptable postures, gestures, and ways to fidget that go mostly unnoticed. Blind children cannot see these body patterns. They do not see that every child in the room holds their head up. They do not see that kids fidget by swinging their legs or twirling their hair. So blind students rock, or make funny facial gestures. Mobility teachers help blind students understand and copy cultural movement patterns. Blind mannerisms are inappropriate body movements (full body postures; hand, arm, and face gestures; and/or fidgeting); signals that do not contain understandable non-verbal and culturally correct information.

Security

Vision grounds the sighted person in space, providing a psychological feeling of well being. For the blind student (without visual grounding), it is uncomfortable to be left in the center of a room without contact with the wall, or a chair, or another person. If blind children are left in unsupported space, with only their feet touching a solid surface, they may feel less secure and the tendancy to develop mannerisms may increase (speculation on my part).

Communication

Vision also plays a huge role in human non-verbal communication. Our full body and arm gestures, facial expressions, eye movements, even pupil fluctuations, send culturally coded signals. We send these signals, and we read those being sent from others. We learn these cultural non-verbal codes from observation. These signals play a large role in the mating rituals of human beings. They are important in the work place, signaling cooperation, competitiveness, humor, worry, the full gamut of human emotion. Blind individuals are at a severe disadvantage because of their inability to send and read cultural signals in a visual world. Their ability to find a mate, find and be successful in a job, and their ability to connect to others emotionally can be adversely affected. A major role for mobility teachers is to help blind students understand the non-verbal communication world of the vision system, and to help them find ways to adjust to this disability. Most blind children need to talk more often and for longer periods to fill in for this communications void.

The face deserves special consideration. Human beings use the face like no other creatures on earth. The human brain contains neural centers that exist solely to identify faces and to read and send facial signals. There is an excellent book called "About Face" by Jonathan Cole, that captures the importance of the face, especially for blind individuals. Sighted persons relate to faces. We "see" our friends and loved ones as faces, and we relate their personalities and voices to the face. Blind individuals relate to voices. This can be very effective, but it is a poor second to the nuances possible with the face. For adventitiously blinded people, the loss of the ability to read and relate to faces, can be a serious psychological burden to deal with. Autistic individuals (and others) can have face blindness, caused by damage to the area of the brain that identifies faces. There is an ebook called "Face Blind!" that is excellent.

Verification

Not only does vision help us label the world, define concepts, and subcategories, it also double checks the work of the other senses. Vision verifies that the coins in the pocket are quarters, that the pie is cherry, and that the voice is Uncle Bill.

Aesthetics

Finally, the arts are primarily visual. Everything from MTV video to the impressionist painters, from computer graphics to High Definition television, from comic books to Sega games, there is a world of entertainment that is not accessible for blind individuals. Many of the pleasures of the modern world come to us through the sense of vision. These pleasures build a sense of well being, of linkage to a historical and creative community. One of the major challenges for mobility specialists is to enrich the lives of blind children.

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