Most people who are totally blind don’t see black. Seeing black is still seeing, and total blindness usually means no visual experience at all, much like what you “see” behind your head.1Nibble Blog. What Do Blind People See? The Science of Sightless Vision What fills that gap depends a lot on whether someone was born blind or lost sight later, and some people who lose their sight end up seeing more light, not less.2BBC News. Do blind people really experience complete darkness?
What Total Blindness Means and Why It Isn’t Black
Doctors define total blindness as having no ability to sense light or shapes. An eye report records it as “NLP,” short for no light perception.3The American Foundation for the Blind. Low Vision and Legal Blindness Terms and Descriptions It is a fairly rare condition. About 85% of people with eye conditions keep some sight, and around 15% are totally blind.4The American Foundation for the Blind. Low Vision and Legal Blindness Terms and Descriptions
The distinction is a real clinical boundary. Eye doctors test light perception by shining a bright light toward the eye, usually when the person can’t read any chart. If the person can say when the light is on, they have light perception, even if nothing else is visible, so someone who can only tell a bright window from a dark room is not totally blind.
When you close your eyes, you still see a dark field, because your eyes and brain are still working.5Nibble Blog. What Do Blind People See? The Science of Sightless Vision In total blindness the brain receives no visual signal, so there is nothing to see, not even black.6Nibble Blog. What Do Blind People See? The Science of Sightless Vision For someone blind from birth, black is a color they have never seen, so it doesn’t describe their experience.
Many totally blind people describe a lack of any visual sense, not a dim or black view, and find the darkness image a poor fit. Descriptions differ, though, and some people who once saw do report darkness or other impressions, so no single phrase covers everyone.
Sight depends on a chain: the eye catches light, the optic nerve carries the signal, and the brain’s vision areas build the experience. A break at any link can cause total blindness, whether severe eye injury or disease, optic nerve damage, or damage to the brain’s vision areas. When the eye or nerve is damaged but the brain’s vision areas are intact, those areas can sometimes produce sensations of their own. That is one reason experiences differ between people with equally complete blindness.
Born Blind Versus Losing Sight Later
One man whose eyes were cut off from his brain described his world not as dark but as full of bright, shifting, colorful light.7BBC News. Do blind people really experience complete darkness? For some people who go blind as adults, the brain keeps producing visual sensations on its own. Those sensations can be distracting rather than comforting.8BBC News. Do blind people really experience complete darkness?
Someone who goes blind as an adult keeps a lifetime of visual memory. They remember faces, colors, and places and can picture them, because the memory is stored in the brain, not the eyes. That helps with everyday tasks, like imagining the layout of a room when told where things are. Over years without new visual input, the pictures can lose detail, so what a person recalls is often broader and less sharp than at first. Some also describe constant light, flickers, or color patterns even with no working eyes, and this varies widely from person to person.
People born blind generally don’t miss seeing the way sighted people imagine. They have no visual memories to lose or compare against, and their sense of the world is built from sound, touch, and smell from the start.
The brain changes after blindness. Both early and late blindness cause the brain’s vision pathways to shrink over time, but only people blind from early in life show wider changes in other brain areas.9PubMed. Brain structural changes in blindness: a systematic review and an anatomical likelihood estimation (ALE) meta-analysis So the brain of someone born blind is organized differently, not just missing sight. Areas that would handle vision in a sighted person take on other jobs, and the whole system is arranged around other senses. A person who lost sight later has a brain built around vision first, so the two groups shouldn’t be assumed to share the same inner experience.
Flashes, Lights and Phantom Images
Spots or flashes of light are a frequent experience after damage to the vision pathways.10PubMed. Anatomical correlate of positive spontaneous visual phenomena: a voxelwise lesion study After strokes affecting vision, about 4 in 10 people saw spontaneous light or images in their blind area.11PubMed. Positive spontaneous visual phenomena limited to the hemianopic field in lesions of central visual pathways In some people who suddenly lost sight, sudden sounds triggered flashes of light that appeared straight ahead.12PubMed. Auditory evoked visual awareness following sudden ocular blindness: an EEG and TMS investigation
These flashes can look like sparks, shimmering patches, colored blobs, or moving patterns, and they vary a lot between people. They arise when something stirs up the vision pathways even though no real light is arriving. They come and go, so noticing what is happening when they appear, such as a loud noise, can help someone describe them to a doctor.
Some people see much more detail. People with serious vision loss can see clear images of faces, patterns, or scenes that aren’t real, a condition called Charles Bonnet syndrome.13PubMed. Complex visual hallucinations in the visually impaired: the Charles Bonnet Syndrome When the eyes stop sending signals, the brain’s vision areas become overexcited and fire on their own, a kind of phantom vision like a phantom limb.14PubMed Central. Hallucinations Experienced by Visually Impaired: Charles Bonnet Syndrome It happens in people whose thinking and memory are otherwise normal, and it is often overlooked.15PubMed. Understanding the Charles Bonnet syndrome: An updated review
Images can appear suddenly, such as a face in a crowd, a pattern across a wall, or a scene that seems real, and they may last seconds or much longer. People usually know the images aren’t real, and they are often pleasant though sometimes upsetting.16PubMed. Complex visual hallucinations in the visually impaired: the Charles Bonnet Syndrome
Phantom images mostly affect people who once saw. Someone born totally blind usually has no such visual hallucinations to describe, and the brain seems to need past visual experience to build pictures this way.
If you or a relative with vision loss starts seeing things, tell the eye doctor. These images are a known effect of sight loss, not a sign of mental illness. Isolation and lack of stimulation can make them worse, so company and activity may help, and some people find relief by blinking, moving the eyes, or changing the lighting.
Hallucinations that come with confusion, disorientation, or memory problems point toward other causes and need a medical check. In Charles Bonnet syndrome, thinking and memory stay normal and the person keeps insight that the images are not real.
Do Blind People See in Their Dreams
Careful sleep studies show that people born blind or blinded in infancy don’t have visual images in their dreams.17Dreaming. Do the blind literally “see” in their dreams? A critique of a recent claim that they do People blinded as teens or young adults often keep visual imagery both awake and dreaming.18Dreaming. Do the blind literally “see” in their dreams? A critique of a recent claim that they do Estimates of the cutoff age range from under about 2 and a half years to about 5 to 7 years.19PubMed Central. Visuo-spatial imagery in dreams of congenitally and early blind: a systematic review
Visual dreams also fade. All blind people have fewer visual dream images than sighted people, and the longer someone has been blind, the shorter, less clear, and less colorful their dream images become.20PubMed. The sensory construction of dreams and nightmare frequency in congenitally blind and late blind individuals
Dreams of people born blind are richer in sound, touch, smell, and taste.21PubMed Central. Mental Imagery in Dreams of Congenitally Blind People Voices, footsteps, textures, smells, and the feeling of moving through space carry the dream. The dreamer often has a strong sense of being somewhere, in a room or street with a layout, even without a picture of it. The people in the dream are recognized by how they sound or move, not by their faces.
A few studies report visual-like dream images even in people born totally blind, and researchers still debate it.22PubMed Central. Mental Imagery in Dreams of Congenitally Blind People A person born blind has never seen anything to compare with, so when they call a dream “visual,” it’s hard to know what they mean. Everyone uses words like “see” loosely, so a report of “seeing” in a dream may only mean knowing or noticing. And since researchers depend on descriptions given after waking, spatial awareness and true visual imagery are hard to tell apart.
Blind and sighted dreams share a lot. Both have stories, fear, joy, and embarrassment. Familiar themes such as being chased, falling, or showing up late can occur, only experienced through sound and touch. The main difference lies in the senses used, not in how emotional or strange the dream is.
How Blind People Picture the World and Understand Color
People born blind build mental maps of their city using touch, hearing, and smell, plus experience and safety cues.23Frontiers of Architectural Research. Perception beyond sight: Investigating the cognitive maps of congenitally blind individuals in urban environments Those maps include routes, landmarks, areas, boundaries, and slopes.24Frontiers of Architectural Research. Perception beyond sight: Investigating the cognitive maps of congenitally blind individuals in urban environments Crossing a familiar city might mean noting the sound of traffic at a corner, the echo near a building wall, the smell of a bakery, and the slope of a sidewalk. These cues join into a map, so the person can plan a route and take shortcuts, not only repeat memorized steps. Blind and sighted people perform similarly on tasks like mentally rotating shapes and estimating distances, because the brain stores space in a form not tied to any one sense.25PubMed Central. Spatial navigation by congenitally blind individuals
In people born blind, the brain’s vision area is used to process sound, especially where sounds come from.26PubMed Central. Functional specialization for auditory-spatial processing in the occipital cortex of congenitally blind humans That isn’t a malfunction. The brain is using available space for the senses it receives, which may help explain why some blind people are very good at judging where sounds originate. Stronger links also form between the hearing and vision areas.27PubMed Central. Corticocortical connections mediate primary visual cortex responses to auditory stimulation in the blind In skilled blind echolocators who click and listen to echoes, the vision area maps echoes by location, and better maps go with better skill.28PubMed Central. Retinotopic-like maps of spatial sound in primary ‘visual’ cortex of blind human echolocators After 10 weeks of click-echo training, both blind and sighted learners showed more vision-area activity to echoes.29PubMed Central. Changes in primary visual and auditory cortex of blind and sighted adults following 10 weeks of click-based echolocation training
Blind people learn about color through words and context, much as anyone learns about ideas they can’t sense directly.30Harvard Gazette. Making sense of how the blind ‘see’ color They reason about color the same way sighted people do, such as expecting two bananas to be the same color.31Hub. Blind people can’t see color but understand it the same way as sighted people They sometimes miss arbitrary color facts, like which fruit is which color.32Hub. Blind people can’t see color but understand it the same way as sighted people
In conversation, words like “see” and “look” are fine; blind people use them too. Describing colors still carries meaning because color has emotional and cultural associations. Describing landmarks, sounds, and layout helps more than pointing or saying “over there.”
Can Technology Give Totally Blind People Sight
Sensory substitution devices turn images into sound or touch. A camera feeds a program that converts the picture into sound, with features such as height and brightness shown by pitch and loudness. Blind users of these devices can locate objects about as accurately as sighted users, around 74% in one test.33PubMed Central. The Topo-Speech sensory substitution system as a method of conveying spatial information to the blind and vision impaired At first it sounds like noise, and users must learn the code over weeks to months of practice. Some blind people using such a device daily reported real visual experiences that developed within months and kept changing for years.34PubMed. Visual experiences in the blind induced by an auditory sensory substitution device Some expert users even began “seeing” when hearing ordinary sounds without the device.35PubMed. Synthetic synaesthesia and sensory substitution
A tongue-based device that turns video into tingling patterns improved basic light and shape tests in people with light perception or worse.36PubMed Central. Clinical Tests of Ultra-Low Vision Used to Evaluate Rudimentary Visual Perceptions Enabled by the BrainPort Vision Device The devices are best at finding things, like a doorway or a cup. Recognizing faces or reading fine detail is much harder, since the sound or touch signal carries far less detail than a real image.
Tiny electrodes placed in the brain’s vision area can make a blind person see small spots of light.37PubMed. Feasibility of a visual prosthesis for the blind based on intracortical microstimulation of the visual cortex In one blind person, an implant produced these spots from every contact over 19 months of testing.38PubMed. Phosphene perceptions and safety of chronic visual cortex stimulation in a blind subject Each contact makes a spot, and many contacts could in principle build a pattern, but these are dots of light, not pictures. Such implants have been tried only in small trials and remain experimental.
Restored sight takes learning. People blind from birth whose sight was surgically restored in childhood couldn’t at first match shapes they saw to shapes they knew by touch, but they learned to do it within days.39MIT News. Shedding light on a longstanding puzzle