The relation between seeing and knowing is more complicated than we commonly assume. For instance, people with normal sight have a blind spot, although they are not usually aware of this hole in their sight. Some people can ‘see’ despite their visual disability. Some people can circumnavigate the clutter without taking a wrong step, while seeing none of it, in a crowded street. Their navigational feat is due to “a weird ability to respond to visual information despite having no conscious knowledge of seeing anything.”
Beatrice de Gelder, a cognitive neuroscientist says that the brain has a number of alternate routes that can be mobilized when the main avenues to vision are blocked. She says it is because the projection of images is not restricted only to the visual cortex, but also to other parts of the brain related to vision and emotion. Though we tend to concentrate on major visual systems in the brain, we may have hidden resources. de Gelder found that a visually impaired man (rendered completely blind by several strokes) could walk unaided through obstacles lying on the way. The experiment suggests that some small amount of information is being transmitted from the man’s undamaged eyes to a more primitive part of his brain, which operates beneath the level of consciousness. The previous experiments by the group (using brain scanning to recognize fearful, angry or joyous faces by observing increased activity in the amygdala region) had suggested that the mind could subconsciously process some visual information. de Gelder’s study shows us the importance of these evolutionary ancient visual paths.
Our conscious vision depends on a region of the brain, called the primary visual cortex. If it is damaged how can one see? How could people see without knowing that they can see? Some experts say that this feat was possible due to the auditory assistance. Some blind people are known to possess the capability to sense the reflection of sound waves, and that assists them to locate obstacles. Various kinds of experiments have revealed that people can unconsciously detect a wide range of visual attributes, including colour, simple shapes, simple motion, and the orientation of lines or gratings. Large shapes, as well as very fine detail, seem hard to detect.
For some visually impaired people loss of sight is not the end of sight. They can see with a special eye. They lose eyesight, but in exchange get many other extraordinary abilities. Some can hear well. “My ears were hearing no better, but I was making better use of them,” said a blind author. Some can see the world around them through their newly acquired hyperactive visual imagination. They discover the world by continuously visualizing the surroundings.