Seeing without Sight

Seeing without Sight

Jessica Wurtz

The brain and the rest of the nervous system is a vast network of neurons, synapses, potentials, and many other critical parts that we might not ever understand.  Just when we think we have finally figured something out about it, it seems that there is always something that contradicts the so-called scientific facts.  One of these curious phenomena is that of how a human being uses their senses to perceive the surrounding environment.  Since we are young, we are taught we have five basic senses: sight, sound, smell, touch, and taste.  While this seems cut and dried, there are circumstances that are a source of confusion, such as when a person is deaf or blind.  Being deaf or blind completely changes the way a person perceives the world and their surroundings.  Often times, the other senses will become much more sensitive, as if to make up for the senses that are not functional.  While it seems natural for this to happen, such as a 3-legged dog who runs just as well as any other dog, a closer look proves that it is not as simple as that.

The most common sense that people think would be enhanced for a blind person is their sense of hearing.  While this is true, there are other factors to determine what senses a blind person uses.  In a study done by Michael Supa et al, blind or blindfolded subjects were placed in a hall under varying circumstances to see how they perceived an object was present and how close they could get without running into it.  There were seven conditions; alternating between walking barefoot on carpet or with shoes on hardwood floors (1).  The subjects who were blindfolded, quickly learned to perceive objects without sight, though the blind remained superior at it.  The blindfolded listed sensory feedback such as the sound of their footsteps, reflection of the object, the shadow of the object on their forehead, facial pressures, or their breath being reflected back to them as reasons as to why they could sense the object’s presence (1).  After the test experiments were completed, they did different experiments to test the theories put forth by the subjects.  In one, they covered all exposed skin, to eliminate any air waves, while allowing sound waves through.  Subjects still performed well, showing that any air waves or reflected breath was not necessary to perceive an object (1).  The next experiment eliminated the subject’s ability to hear, and the subjects failed to locate the object at all.  The final experiment was to have a subject listen to the sound transmitted by an experimenter approaching the object to see if hearing alone was sufficient to perceive an object.  This was indeed the case, as the subjects were able to perceive the object and prevent the experimenter from running into it as well as they could while they were doing it themselves (1).

This experiment shows that hearing indeed plays the most important role in allowing a blind person to perceive the surrounding environment, but that there are other tools the nervous system can use to aid in this task.  This study was very satisfactory in that it fit with assumptions of what senses take over when a person is unable to see.  However, as this avenue was investigated, other questions began to pop up, such as what does “seeing” mean?  How is it defined? How do the brain and the nervous system make these adaptations?  These questions led to other veins of research in order to form a clearer picture of what kind of perceptions a blind person has and how they work.

A blind Turkish artist named Esref Armagan was studied because it was unknown how a person who never had the ability to see could produce beautiful paintings easily recognizable by any sighted person (2).  Armagan was tested by being given objects and then asked to draw them from many different perspectives, which he did perfectly with no difficulty (2).  Next, he was given objects to draw or recall while he scribbles while his brain is scanned to see what parts of his brain are active during these tasks.  When Armagan recalled objects, his visual cortex lit up some, but when he drew, his visual cortex lit up in an almost identical manner as a person who is actually looking at something (2).  It seems that the visual cortex has a different role in seeing than it has been thought.  Even people who can see use the same areas of their visual cortex when they are imagining something rather than actually looking at it.  The mind can produce an image in the “mind’s eye” even without the ability to use real eyes to first see something in real life.  However, while it makes sense that the mind can conjure an image of something that can be touched and then created in the mind, the fact that Armagan can draw the shadows cast by on object from any angle or perspective is not explained by this.  If one had never seen how a shadow is cast, would that be something that could be learned without ever actually seeing it?  Somehow, this is possible, as in Esref Armagan’s case. 

This redefines the commonly held thought on what seeing is, that it requires the sight of a person’s eyes.  Despite the fact that this does not fit with the usual definition, when one thinks of the mind’s ability to imagine things, both while awake, and during dreams, it should not come as a surprise that a blind person can “see” something they have never physically seen.  It is possible to imagine or dream about a fantastical creature that does not exist in real life or to “see” a place one has never been.  Esref Armagan does the same thing, only his sense of color has been told to him, and he has memorized what objects are what colors and what colors clash when they are put together (2).

The next question to address is how the brain is capable of making these adaptations in perception and “seeing” when the sense of sight does not function.  The phrase that is used to explain this phenomenon is “neural plasticity”.  This refers to the changes that occur in the organization of the brain, especially in a specific area, that are a result from experience (3).  This somewhat vague definition is only satisfactory at the surface level.  It makes sense that the brain would reorganize if the eyes did not work, but this does not clarify as to how the brain knows where to move things to, or even how it would go about doing that.  The studies with the blindfolded people as well as with Esref Armagan also seem to contradict the theory of neural plasticity to some extent, though not completely.  The blindfolded subjects could perceive objects despite the fact that they had no practice doing so without sight.  The truly blind were slightly better due to the years of practice and honing of these other senses, but there was not really a learning curve for the sighted, they picked up very quickly how to use those other senses, especially hearing.  Also, everyone uses their visual cortex to both physically see something as well as see something in their mind’s eye, whether or not they are blind.

It seems that all people have to ability to use these extra senses in the body if they need to when they cannot see, but that it is so much easier to just use the eyes that those abilities are overshadowed.  So, blind people, may not in fact have heightened senses after all, they simply have to rely on the senses that are already present in all people because they do not have the luxury to use their eyes.  While this was not the expected answer to the question of how blind people develop heightened senses, it was interesting to discover that we all have the ability to use our senses at a much higher level.

Works Cited

1). Supa, Michael, Milton Cotzin, and Karl M. Dallenbach. “Facial Vision: The Perception of Obstacles by the Blind.” The American Journal of Psychology. 53 (1944): 133-183.

  2). http://www.newscientist.com/channel/being-human/mg18524841.700 “Senses special: The art of seeing without sight” Alison Motluk, article on NewScientist.com.

3). /bb/neuro/neuro98/202s98-paper2/Casasanto2.html “Neuromodulation and Neural Plasticity” Daniel Casasanto, student paper on Serendip website.