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Why Are We Conscious?

Apart from the challenge of isolating the causal basis of consciousness, there is the question of why consciousness exists in the first place. One might say that consciousness simply evolved in nature—it is a fact of evolutionary biology. But what evolutionary advantage did it offer? How did consciousness evolve in certain animals, and why did it remain and develop in more complex forms? We could imagine life evolving without conscious creatures. Consciousness couldn’t have happened as a random occurrence—or could it? This question becomes intriguing when we consider some nonconscious ways of performing tasks that would seem to require consciousness.

Consciousness and Blindsight

Some people can interact with the world as if they were seeing, but without a conscious experience. So-called blindsighters see nothing in an area of their visual field because of corresponding primary visual cortex damage. But when they are presented with simple geometrical figures—crosses or circles in their blind areas— they can tell you what is projected and its orientation. Some can navigate through hallways they have not walked through before, with obstacles on the floor, but without bumping into them.

Blindsight may seem unusual, but we are all blindsighters—ordinary vision masks our capacity for blindsight. This morning, I went running on the beach and came to a stretch full of small rocks. I was going fast, enjoying the small challenge, without fear of tripping, thanks to blindsight. There is no time to think about what your feet do in a situation like that—their dance in an unknown territory of small rocks can happen only with automatic support from nonconscious visual-guidance systems.

If this simple example seems unconvincing, think of yourself as a professional tennis player returning a serve at 150 mph. Having no time to go through what to do, how you move is something you learn about after your return. Nonconscious systems for visually guided action take over. Sight is not the only sense that operates in this way. Many hidden systems guide us in the world at a level beneath consciousness.

People can guess smells, although they don’t consciously smell anything. In one experiment, subjects sniffed test tubes with a banana smell of such low concentration that they were unaware of it. Yet, when asked to simply take a wild guess of what the smell was, they guessed significantly better than chance. What is the use of such a system? Could it change your mood or perception of an environment or a person, although you never became conscious of the smells? We don’t know much about how such smelling without conscious awareness operates. There are also people who cannot consciously recognize faces (prosopagnosics) but nevertheless respond on a deep unconscious level as if they did. Their galvanic skin response is different when they are shown faces of people they are familiar with, as opposed to strangers, and we all respond to faces on this deep nonconscious level. Deaf hearing is another variant on this theme of virtual senses, and there is also blind touch. As with blindsight, deaf hearing and blind touch can occur as a result of damage at an early sensory processing stage. For vision, it is visual processing area 1 (V1); for deaf hearing, it is auditory processing area 1 (A1); and for blind touch, it is somatosensory processing area 1 (S1).

Evolution of Virtual and Conscious Seeing

Having evolved early in comparison with conscious perception, nonconscious sensory-guided action systems are found throughout the animal world. Vision apparently evolved first for action, not for conscious perception (Goodale and Milner 1992). If nonconscious systems can perform sophisticated tasks, why wasn’t this enough? It’s tempting to say that consciousness gives us awareness of our environment, but how could awareness be isolated from consciousness? Are they not the same thing? It does not seem to add much to say that consciousness gives us awareness.

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