Vision consists of your eyes detecting  light and converting it to electro-chemical impulses in neurons which are then given meaning by your brain.   Hence, the real “seeing” occurs in the brain with the interpretation of the impulses. For this reason, as long as input from the surrounding world can be delivered to the brain, through any means, for example taste or touch, and the brain can learn to make sense of it, seeing can take place.  Substituting one sense for another has allowed people to successfully see the world without vision.

In his book, Incognito: The Secret Lives of the Brain, David Eagleman tells of Paul Bach-y-Rita, a  neuroscientist at the University of Wisconsin, who, in the 1960’s, developed a device which presented a tactile display to blind people in effect allowing them to see.  The blind subjects had a video camera attached to their foreheads.  The information from the video camera was converted into tiny vibrations on their backs.  Of course, at first, they were bumping into things, and it was nothing like vision.  However, after wearing these visual-tactile substitution glasses for a week and learning to correctly translate the vibrations into movement instruction, they became quite skilled.

But, there is more.  Eagleman writes:

The stunning part is that they actually began to perceive the tactile input – to see with it.  After enough practice, the tactile input becomes more than a cognitive puzzle that needs translation;  it becomes a direct sensation.

If it seems strange that nerve signals coming from the back can represent vision, bear in mind that your own sense of vision is carried by nothing but millions of nerve signals that just happen to travel along different cables.  Your brain is encased in absolute blackness in the vault of your skull.  It doesn’t see anything.  All it knows are these little signals and nothing else.  And yet you perceive the world in shades of brightness and colors.  Your brain is in the dark but your mind constructs the light.

To the brain, it does not matter where those pulses come from – the eyes, the ears, or somewhere else entirely.  As long as they consistently correlate with your own movements as you push, thump, and kick things, your brain can construct the direct perception we call vision.

He tells the story of Eric Weihenmayer, an extreme rock climber, who is blind, but  has learned to see with his tongue.  In 2001, he became the first blind person to climb Mount Everest.  While climbing, Eric uses something called a BrainPort which takes video input and translates it into patterns of electrical pulses onto a grid of over 600 electrodes in his mouth.  This allows Eric to discern qualities usually associated with vision such as distance, shape, direction of movement and size.

Demonstrating the concept in reverse, Eagleman tells the story of Mike May who was blinded by a chemical explosion at the age of three.  Forty-three years later his vision was restored by a new surgical development. The bandages were removed, and Mike was to look upon the faces of his children for the first time.  What was supposed to be a heart warming scene, was not.  Although his eyes were working perfectly, Mike did not have vision because his brain could not make sense of the torrent of input from his eyes.  With learning, over time, Mike came to have the experience of sight.

Vision is learned.  Seeing is in the brain.

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  1. Stephen Gemmell Reply

    Hi Debbie, fascinating post and loved the couple of examples you quoted. Reminds me of: ‘There are none so blind as those who cannot see’. ‘And although seeing, yet they did not understand’. I guess that the extreme rock climber therefore wasn’t blind from birth and that the BrainPort pulses triggered a brain recollection of climbs when he was sighted? And so by the same token, over the forty odd years since losing his sight, Mike May’s brain had unlearned or forgotten ‘simple’ tasks like facial observation and recognition. Fascinating. Take care, Stephen

    • Debbie Hampton Reply

      Hey, Steve! Thank you, as always, for commenting. Eric Weihenmayer was born with a rare eye disease called retinoschisis and went completely blind at 13 years old. I would think a person would have to have had sight at one time to even understand some of the concepts associated with vision. For example, if you had never seen color would it make sense conceptually?

  2. I have done some research on the brain and what is said here is true. The brain is the decoder of information/waveforms that causes us to perceive reality a certain way.

    • Debbie Hampton Reply

      When we expand our way of thinking about the senses, the possibilities for delivering impulses about the world around us to the brain, and it learning to interpret them are exciting!

  3. Thomas Eklund Reply

    Hi Debbie, this is fascinating indeed! One thought that came to my mind is that while it is possible to learn to interpret input correctly (however we define that), it is also possible to learn to interpret input incorrectly, especially if emotional responses are involved – fear, for example. This, of course, applies to people with working vision and other senses as well.

    Your thoughts on this?

    • Debbie Hampton Reply

      Thomas, thank you for commenting and raising an interesting question. Although, I am not exactly clear what you mean. I do not see how “correct” and “incorrect” could even be universally defined. Of course, there can be a standard determined. I mean, what your brain interprets as bright red may be a completely different shade of red to me. What your brain may interpret through your skin as being hot, my brain may interpret the same signals as warm. Is there any one more correct than another?

      Yes, I would think that, when our brain learns to interpret things with accompanying emotions such as fear, it alters the interpretation of the signals. This, I think, is why there are such things as PTSD. The good thing is that such learning can be unlearned in the brain as well.

  4. Thomas Eklund Reply

    Yes, I agree with you. I should have clarified my thought a bit further. This topic can easily become very complex, though. Even such things as defining, in this context, “right” and “wrong” both concisely and sufficiently comprehensively would take a lot of effort and time. That’s, however, only a small part of the bundle of the topics that are involved. So, I will simply try to address what I meant in very general terms.

    Even when all the senses work in an optimal manner, we can use all of our senses and still make incorrect conclusions and, consequently, also develop less than optimal behavior patterns.

    It seems that when one or more of the senses are impaired, it is likely that we can compensate by using other senses. That’s what your article is about as well, isn’t it?

    I’m just wondering if in such cases people who compensate this way would benefit from using some extra methods that help in decision-making processes.

    Please accept my apology for not being able to explain the relevant concepts very concisely. However, I will give an example that comes from a different, but related realm – business management.

    Especially in today’s world, people need to work remotely and also internationally. There are various reasons why working virtually, or, as I like to call it, working in technology connected environment, has not been as successful as it should and could be. One of them is that we cannot use our sense of vision as effectively when we interact with people remotely, as we can when we interact with them in person. We cannot interpret body movements of the other person, visual cues and other such stimuli. Even tone of voice can make a big difference in some instances, just like the means of communication can. Say something to another person or write the same sentences in an email, and you can end up with two very different outcomes.

    So, we would need to use compensating methods – in the above case, video conferencing, and so on. I guess, somewhat similarly, when one sense is impaired and the others compensate, the person would want to use some additional method or methods for interpreting the input.

    To put it differently, compensating for a specific sense alone may not produce the needed results. Integrating the compensation method with other senses, so that there is some sort of comparison and evaluation method involved, would probably produce more valid and reliable results.

    This is just a thought, though. As I said, this can easily get very complicated, because so many complex areas get involved. Each area has its own brances, like the tree that’s on your websites. Too complicated, perhaps, for a blogging conversation 🙂 But it’s all interesting material, of course.

    • Debbie Hampton Reply

      Thomas, you raise some very thought provoking points. Please understand that I am not contradicting your thoughts in any way. I am thinking out loud and questioning. I don’t think I am saying that one of the senses can compensate for another here. I am saying that these alternative forms of getting information to the brain ARE vision. Yes, it is limited, but it is what we define as vision. It is the brains’ interpretation of the environment to make a mental representation just the same as it would with input from the eyes. Maybe I am being too literal here.

      I agree that, when one sense is gone, the information available to our brains, even with such an amazing device as the Brainport, is severely limited. The example you give of communicating through technology is perfect here. So, yes, I would agree that when one or more of the senses are impaired, extra methods that deliver more information can only help in decision making and discernment. The more information the better by whatever means, I would think. You are right that just compensating for some attributes via one method is not likely to give the whole picture. Thank you for your thoughts.

      • Thomas Eklund Reply

        I guess that depends on the definition of vision. If you define it as “perception resulting from the ability to interpret information and surroundings from the effects of visible light reaching the eye,” then that is something else, isn’t it, than are the alternative forms of getting information to the brain.

        • Thomas Eklund Reply

          Maybe, instead of using the word “compensate” I should have said “supplement.” That is, other senses can supplement signals to the brain that end up being processed in the brain at least somewhat similarly as the brain processes vision. However, can you say that the outcome is in every way as good as what is commonly known as vision? If not, then we are back in my previous longer entry.

          Just clarifying this 🙂

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