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To See Without Sight

emily's picture

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In my last paper, I wrote about vision as a function of the brain and explained that what we see corresponds with what neurons are active, whether due to outside stimuli or processes within the brain. I would now like to consider the idea that we see with our brains and not with our eyes in a different context. Does the experience of seeing depend on ever having seen? In order to answer this question, I want to consider the congenitally blind, from what they see before and after recovering form vision, to the varying prosthetics available to help blind people “see”. By demonstrating how the congenitally blind use all their senses for visual imagery, I hope to show that vision is not only a function of the brain, but one does not necessarily need functioning eyes to be able to see.

Can the congenitally blind “see”? Many scientists would say yes, that people who are born blind are capable of visual imagery. For example, in their study on imagery in the congenitally blind, Jerome Zimler and Janice M. Keenan found that the performances of the congenitally blind adults and children in tasks presumed to involve visual imagery in memory were remarkably similar to the performances of sighted adults and children in the same tasks. In the first two experiments, subjects were asked t  aso recall certain associated words, which were (in experiment 1) high in either visual or auditory imagery or (in experiment 2) grouped by specific attributes such as color or sound. Zimler and Keenan found that the congenitally blind subjects were able to recall more word pairs with high-visual-imagery and more words grouped by colors, just as well as the sighted subjects. According to Zimler and Keenan, these results suggest that either the sighted are not using visual imagery or that visual imagery used by sighted people is “no more facilitating than the abstract semantic representations used by the blind”[1]. In other words, in discovering that the congenitally blind subjects performed just as well in the imagery tasks as the sighted subjects, Zimler and Keenan concluded that blind subjects are just as capable as the sighted subjects of visualization, even if they might do so in a different manner. In their third experiment, subjects formed images of scenes in which target objects were described as either visible or concealed by another object in the picture plane; when asked to recall the target objects, both blind and sighted subjects recalled more visible objects than concealed objects. This suggests that the blind use occlusion in imagery just as the sighted do with visual imagery, providing another example for the visualization capabilities of the blind. [1]

Zimler and Keenan’s study may seem abstract. If the congenitally blind subjects cannot physically “see”, then how are they able to visualize as well as the sighted subjects? Psychologist Helder Bértolo answers this in his paper arguing that congenitally blind are indeed capable of visual imagery without visual perception; as he shows in his experiments, congenitally blind have visual contents in their dreams and are able to draw those visual contents. Bértolo starts off explaining that it is hard to study visual imagery because the visual imagery experience is “personal and difficult to access”, but dreams with visual content are forms of visual imagery. Because dreaming is associated with visual activity for sighted subjects, the idea that blind people do not dream had been widely accepted. However, there have been many experiments done to refute this idea, showing that dreams of the blind are “vivid and self-engaging”, either containing just sounds, touch sensations, and emotional experiences or even actual visual components. Bértolo showed in his experiment that the congenitally blind are capable of having dreams with visual components. His subjects showed the ability to verbally describe the visual content in their dreams and to draw graphical representations of such content. According to his results, the congenitally blind, who never experienced visual perception, are able to visualize. Bértolo then says that his results have led him to hypothesize “that blind subjects can produce virtual images, that is, that their dreams correspond to the activation of visual cortical regions”. In other words, visual imagery does not depend on specific visual perception, but can arrive from the activation of the visual cortex (or, the neurons responsible for sighted vision) by any other means. Specifically, Bértolo claims that several other authors have established the fact that congenitally blind subjects use their visual cortex to process other inputs, like auditory and tactile [2]. In response to Bértolo’s experiment, Fernando Henrique Lopes da Silva claims that these inputs can create virtual images in the brains of congenitally blind. Because the congenitally blind are capable of visual imagery without the experience of visual perception, the congenitally blind must be capable of using some other sensory modes to integrate inputs into the visual system in order “to produce concepts capable of graphical representation”. In other words, other sensory inputs can activate the visual cortices of the congenitally blind; since the visual cortex is responsible for sighted vision, congenitally blind people can “see”, or, visualize, with their other senses, when messages from other sensory organs activate the visual cortex. [3]

What happens, then when congenitally blind people recover the ability for visual perception? Having never relied on visual perception for visual imagery before, would the right sensory connections be there, or would these subjects still rely on other sensory input to be able to see? In Richard Gregory’s example of a patient named S.B., when the bandages were removed after the surgery, S.B. saw nothing but a “blur”. He heard the voice of the doctor coming from this blur and realized that the blur must be a face. He did not suddenly see a world of objects, as we do when we open our eyes, because neuronal connections from visual input had not been established yet. When we recognize a book, for instance, it is because we can link our concept of “book” to the visual perception our brain tells us we see; S.B., on the other hand, could not link the concept of “book” to any sort of visual perception because such a visual perception had never existed for him before [4]. As Oliver Sacks says in his account of a similar patient named Virgil:


There were no visual memories to support a perception; there was no world of experience and meaning awaiting him. He saw, but what he saw had no coherence. His retina and optic nerve were active, transmitting impulses, but his brain could make no sense of them; he was, as neurologists say, agnostic. [5]


To Gregory’s surprise, however, S.B. was able to recognize capital letters and numbers by sight. S.B. had learned uppercase letters and numbers by touch at the blind school he attended when he was a child, from inscribed letters on wooden blocks. The fact that he could read letters visually, which he had learned already by touch, “showed that he was able to use previous touch experience for his new-found vision”. According to Gregory, this indicates that there seems to be a “general knowledge-base available to all the senses” [4]. What Gregory means is just what Bértolo found in his experiments. We use all of our senses to create concepts. S.B. could see the capital letters and numbers because the way in which his brain was stimulated when he saw the letters and numbers was the same way it was stimulated by tactile input; S.B. used his sense of touch “to produce [a concept] capable of graphical representation”, a capital letter or a number. Thus, patients recovering their vision “learn” to see by associating things they know by other senses with what they see, adding to their previous neuronal patterns, or concepts of things. However, there are many things one sees that one might never have had the chance of touching. Gregory shows several of S.B.’s progressive drawings of a bus, and he is never able to draw the front of a bus because he could never feel what that was like. Also, many things like size and distance have to be learned through experience.

       In many cases, from S.B. to different accounts done by Marius von Senden in his book Space and Sight, patients who undergo sight restorative operations have a hard time adjusting to visual perception, often resorting back to being blind (i.e. closing their eyes in order to actually “see” something) [6],[7]..,.  While the results vary, many patients become depressed for a variety of reasons; for example, S.B. became depressed because he “found the world drab”, becoming more upset as he found more imperfections in things as he “evidently [expected] a more perfect world” [4]. A person who has recovered their sight will never be able to see the way a person born with vision sees. Visualization develops in a congenitally blind person in such a different way, that trying to change how that person visualizes is like trying to teach a person to write with their left hand. They may get better at it, but they will never write as well as with their right hand because the connections did not develop early in life, and instead, the brain grew accustomed to other connections.

        There are many visual prosthetics that aim to restore sight by means of correction within the eye, for example, by using electrodes in place of retinal cells. Prosthetics like this are similar to surgical sight restoration because the patient must learn how to analyze his or her new “sight”, whether they can see as well as sighted people can see or more rudimentary (shadows or shades). Instead of the sudden use of a new sense, other visual prosthetics use a blind person’s working senses to enhance their visual experience. One example of this is the vOICe vision technology (Oh, I see!), which offers “the experience of live camera views through sophisticated image-to-sound renderings” [8]. The theory behind vOICe is “crossmodal sensory integration” [8], or, employment of the existing multisensory processing within the brain. The technology uses visual input from a “web cam” and translates the images into “closely corresponding sounds” [8]. Peter Meijer, inventor of vOICe, says one can learn to sense instinctively how the features the specific auditory information correspond to objects in the physical world [8]. Another prosthetic, although still in its investigational stages, called BrainPort Vision, is a device for “orientation, mobility, object identification, and spot reading”[9] using the tongue and a camera system. Visual information is collected from the video camera, similar to the vOICe vision technology, but the information is translated into electrical stimulation patterns on the surface of the tongue: “users describe it as pictures drawn on their tongue with champagne bubbles” [9]. Again, patients need practice, but once they are trained, they would be able to correspond the patterns on their tongues with qualities, location, and motion of objects in their environments [9]. With prosthetics like vOICe and BrainPort Vision, congenitally blind patients can use the senses they already have to “see”, or to interact better with, their external world.

        To answer the question posed in the beginning, the experience of seeing does not depend on ever having seen. Throughout the given examples, I have concluded that a congenitally blind person can use their other senses to “see”. This is called synesthesia, a condition in which one type of sensory stimulation evokes a different sensation. Many historical artists, such as musician John Mayer, have synethesia, and can perceive color when they hear music, or hear sounds when seeing colors. Indeed all sighted people experience synesthesia to some degree: we associate sounds and sights constantly, from the crackling of thunder associated with lightning, or the soft, splashing sound associated with ripples in a pond [10]. Our senses are not isolated and our sensory organs are not responsible for our sensations. Rather, input from our sensory organs meet in our brain, which tells us what sensations we feel. In other words, we sense with our brain, not with our sensory organs. Our senses are not dependent on a particular input pathway: as long as the right pathway within the brain is stimulated, we will experience a given sense, whether or not the input comes from the expected sensory organ.


Works Cited:

[1] Zimler, J. and J.M. Keenan. Imagery in the congenitally blind: How visual are visual images?. Journal of Experimental Psychology: Learning, Memory, & Cognition [Internet]. 1983 [cited 2010 March 28]; 9(2): 117-349. Available from:

[2] Bértolo, H. Visual imagery without visual perception?. Psicológica [Internet]. 2005 [cited 2010 March 28]; 26: 173-188. Available from:

[3] Lopes da Silva, F.H. (2003). Visual dreams in the congenitally blind?. Trends in Cognitive Sciences [Internet]. 2003 [cited 2010 March 2]; 7(8): 328-330. Available from:

[4] Gregory, R.L. Eye and Brain: The Psychology of Seeing. Princeton, NJ: Princeton University Press, 1997. 153-158.

[5] Sacks, O. An Anthropologist on Mars: Seven Paradoxical Tales. New York, NY: Vintage Books; 1996. 108-151.

[6] Von Senden, M. Space and Sight. Great Britain: Butler & Tanner Ltd, Frome and London, 1960.

[7] Dillard, A. Pilgrim at Tinker Creek. New York, Ny: HarperCollins Publishers, Inc.; 1974. 17-36.

[8] Meijer, P.B.L. Augmented Reality for the Totally Blind [Internet]. The vOICe Technology; [2010 March 6; 2010 March 28]. Available at:

[9] BrainPort Vision [Internet]. BrainPort Technologies, Wicab, Inc.; [cited 2010 March 28]. Available at:

[10] Grobstein, P. Perception: From Five Senses through Synesthesia. Serendip [Internet]. [2009 March 19; 2010 March 27]. Available from /exchange/grobstein/perception




Nagesh's picture

Very validating study !

Hi ,

I have come to this article due to the pursuits my mind is up to ..! Let me give you the background & then make the point i was trying to make .

My indian spiritual texts (>5000 years old) says that there are 3-bodies in a human being -

sthoola body (Gross or physical body) - Active & primary while we are in a concious state .
sukhma body (subtle or pranic body) - Active & primary while we are in a dream state . 'the sthoola body' has no role in this state & is dormant.
karana body (Causal body) - Active & primary while we are in a deep sleep state. The above other two are dormant.

So when we are dreaming and visualizing , it says our concious state & its experiences are not the ones which are causing the dreams but the 'sukhma body & its experiences ' !

So my point is that , what we are seeing in the dream state is not the contribution of the concious experiences but those that are coming out of the pre-existing experiences which are preserved in the sukhma body ! That might be an acumulation out of the previous memories from the previous births we might have had ! So, in the context of a congenitally blind , what we are visualizing is not so much due to our ability to process the information we are getting through other senses but because of the pre-existing visual experiences which were already there ? from our past lives !

Ofcourse , i don;t have any instances of any experiments or other scientific data but seems compelling from a personal experience point of view.

I would be happy to hear comments on this & also any data which can prove or disprove this hypothesis.


Paul Grobstein's picture

seeing without eyes and its implications

"as long as the right pathway within the brain is stimulated, we will experience a given sense, whether or not the input comes from the expected sensory organ"

This raises, in my mind at least, the intriguing possibility that the "senses" aren't in fact particular ways of receiving information but instead different ways of processing it, and that we're born with several distinct ways of processing information that can be used for any of a variety of inputs.  And then the question, what is distinct about each of them?  "Vision," for example, might be distinctive in processing in terms of spatial location, edges, and "objects."  Where as hearing is ... ?  Ditto touch, smell, taste?  I wonder whether "visual processing" accounts for the spatial characteristics of hearing?