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Most of us cannot conceive of life without vision. The gradual decline of eyesight is often a sign of aging, while others have never known sight at all, having been blind since birth. Despite this, there have been some truly remarkable discoveries in the science and psychology of blindness.
10. Deja Vu
Deja vu refers to the sensation of having already experienced a current event. One possible explanation is a slight delay in the process between when an image reaches the eyes and when it is recognized by the brain. While we still don't know if this theory is correct, it might suggest that blind individuals do not experience deja vu.
But oddly enough, they are able to.
The University of Leeds is a leader in research on deja vu. While the experience may be mildly bothersome for most, it can be even more frustrating for individuals who suffer from what’s known as 'chronic deja vu.' The researchers also documented the first confirmed case of a blind man who experienced deja vu, emphasizing that they are quite certain there are more such cases out there.
For the blind man, deja vu was triggered by a specific combination of events or activities. In the official report, it was noted that the sensation of deja vu occurred when he unzipped a jacket while a certain song was playing on the radio. This confirmed that the sensation is not merely caused by a disruption in the optical nerves and pathways.
The blind man shared that the most frequent trigger was sound, whether it was a piece of music or a brief conversation that evoked a sense of familiarity. Often, sound combined with other senses, like smell, to create the feeling of having already lived through the experience.
As a result, the researchers are shifting their focus away from a stimulus-based explanation for deja vu. Instead, they are working on a new theory that revolves around disruptions in brain signals and how such disruptions influence our sense of familiarity with certain experiences.
9. Navigating Through Geomagnetism
Scientists at the University of Tokyo have been investigating whether the brain can rely on alternative sensory inputs when deprived of visual stimuli. Recent experiments on rats have shown that the brain can indeed adapt and learn to interpret information through other senses—including the ability to detect geomagnetism.
The researchers equipped blind rats with digital compasses similar to those found in smartphones. Microelectrodes stimulated the rats’ brains, helping them understand which direction they were facing. When they faced north, the right visual cortex was stimulated. If they faced south, it was the left visual cortex that responded.
The rats were then placed in a maze, where researchers observed that they were creating a mental map of their environment using the data transmitted from the compass. Within just two days, the blind rats were able to navigate as swiftly and accurately as the sighted control group. The rats' behavior suggested that it wasn't mere guesswork. They would travel in a straight line and then adjust their course, regardless of where they started in the maze.
Yuji Ikegaya, the lead researcher, confesses that he has no clear understanding of how the rats are constructing such a detailed mental map of the maze. However, this discovery implies that the brain can adapt to utilize alternative forms of input in place of visual cues and become just as proficient in navigating using them.
8. Universal Body Language
We often rely on body language for communication in daily life. But the question remains: Is it a learned skill or something innate from birth? To investigate, researchers from the University of British Columbia and San Francisco State University studied how different cultures express emotions like happiness and shame through body language. While part of their research focused on athletes in the 2004 Olympic Games, another fascinating aspect examined participants in the Paralympics.
The study involved 108 judo athletes, including 12 who were blind from birth and 41 who lost their sight later in life. The researchers discovered that, regardless of their country of origin, all of the competitors demonstrated similar body language when they won or lost.
Photos taken after the matches revealed only minor differences in behavior. Sighted competitors from North America and Europe appeared to conceal their shame and disappointment at a loss slightly better than their counterparts. Blind competitors, however, seemed less focused on hiding these emotions, suggesting that the sighted athletes' reactions were more aligned with the cultural expectations of their countries.
These findings support the notion that body language is not something we need to be taught. It’s an instinctual behavior that transcends cultural boundaries and, in some instances, even connects us to our closest nonhuman relatives. From the defeated slouch of the losers to the triumphant puffed chest of the winners, our body language is shared with animals like gorillas, and it’s not something we need to learn from others.
7. Blindsight
Blindness can occur in various ways. While we often associate it with eye problems, this isn't always the case. Some patients—like T.N. and D.B.—have a condition called 'blindsight,' which allows them to perceive and react to visual stimuli without consciously realizing it.
T.N. was a doctor who experienced multiple strokes that affected the visual cortex on both sides of his brain. Although his eyes remained functional in receiving visual input, the strokes seemed to have impaired his brain's ability to process that information.
At the University of Bangor in Wales, experiments revealed that T.N. possessed an astonishing ability to sense his surroundings without consciously recognizing it. He could identify emotions on people's faces, navigate around obstacles, and even determine the orientation of a rod on the wall. However, he couldn’t detect light, as demonstrated when he was shown a flickering screen and asked to identify dark circles on it.
Similarly, D.B. became partially blind after undergoing surgery to treat chronic headaches. Despite his belief that he couldn’t see anything, tests demonstrated that his blind side was able to process visual inputs surprisingly well.
But blindsight doesn’t only manifest when moving through spaces or avoiding obstacles. Patients with blindsight have been shown to react physically to certain stimuli. In particular, they often display signs of stress when viewing an image of a frightened person.
Even the scientists who have interviewed and tested individuals with blindsight are still uncertain about the mechanism behind it, but it may be related to V1, the area of the brain believed to translate sensory information into conscious awareness. When V1 is damaged, a disconnect occurs between the sensory input received by the brain and the awareness of that input, enabling some blind individuals to respond to stimuli they aren’t consciously aware of.
6. The Benefit of Having Blind Parents
Making eye contact is crucial for bonding at any age, and for babies, it's one of the first methods they use to engage with others. A team from Birkbeck, University of London, explored how the absence of eye contact in the babies of blind parents influenced their development during the early months. The findings were unexpected. It turns out these babies developed alternative communication strategies that were not observed in the babies of sighted parents.
The communication abilities of these babies and their parents were observed at three different stages: six to 10 months, 12 to 15 months, and 24 to 47 months. Babies with blind mothers made eye contact with and connected with sighted people as any other baby would, but they demonstrated faster response times compared to their peers born to sighted parents.
While babies of blind mothers tended to make less eye contact with their mothers than those with sighted mothers, their interactions with other adults were similar to those of their peers. These babies also developed unique methods of communicating with their blind mothers.
For instance, babies of blind mothers were found to be more vocal when interacting with their mothers than with other adults or even their fathers. This led researchers to conclude that these babies also displayed superior visual memory and communication skills compared to their peers. The researchers compare this to children growing up in bilingual households, where they learn multiple methods of communication from an early age, benefiting them long-term.
5. Dreams of the Blind
In a study published in the journal Sleep Medicine, Danish researchers examined the differences in dreams between sighted and blind individuals. The study involved 50 volunteers, including 14 people who were blind from birth, 11 who lost their sight after the age of one, and 25 sighted participants. For a month, the volunteers recorded their dream details, including colors, emotions, people, and other sensory experiences.
None of the blind participants reported seeing anything in their dreams. However, almost 20 percent of them experienced taste in their dreams, 70 percent recalled touching something specific, and 86 percent heard sounds. These percentages were significantly higher compared to the sighted group. Among those blind from birth, 93 percent reported hearing sounds in their dreams. Interestingly, while the emotional content of dreams was generally similar across all groups, the blind were far more likely to have nightmares.
For individuals born blind, approximately 25 percent of their dreams are nightmares, a striking contrast to the 6 percent average seen in sighted people. One blind participant shared that she had been haunted by recurring nightmares throughout her life, often involving falling, being followed, or being hit by a car.
Other blind participants described dreams filled with intensely embarrassing social situations. Researchers theorize that the increased frequency of nightmares in blind individuals might be tied to the daily dangers they face. They suggest that the higher occurrence of these nightmares could be linked to the extra processing time needed by blind people to store potential risks in their memories. Dreams might serve as a way to consolidate experiences into lasting memories. If this is the case, the frequent nightmares among the blind could be a reinforcement of survival skills.
4. Visualizing the World
In addition to varying levels of blindness, there are also a surprisingly diverse range of ways blind people mentally picture the world around them.
Paul Gabias, who became blind shortly after birth, claims that he has no difficulty visualizing his surroundings in his mind. From the height to the depth and texture, his mental images are just as vivid as those of a sighted person—except for one significant difference. His mental images lack color, and black and white are concepts foreign to him.
Gabias, a psychologist and professor at the University of British Columbia, has been researching how a blind person forms mental maps of their environment, much like a sighted person would. Brain imaging scans suggest that the neural pathways involved in creating mental maps in sighted individuals are the same ones that function in blind individuals.
Sensory inputs, like those from Braille letters, pass through the visual cortex and are processed similarly to how visual stimuli are handled. The same is true for individuals who use echolocation with other sensory inputs. That information also travels through the visual cortex. For example, volunteers who listened to recordings of their tongue clicks for navigation were able to identify the objects producing the echoes from the sounds.
Others, like BBC journalist Damon Rose, who lost his sight due to surgery as a child, report different experiences. Rose now describes missing the darkness. Instead, he sees an overwhelming amount of light that persists regardless of the time of day or his activities. He perceives a brown background, colorful geometric shapes, clouds, and squiggles. Initially, his ‘built-in fireworks’ gave him hope that he might one day regain his sight. However, now he is convinced that his brain is generating images since it no longer receives any external visual stimuli.
3. Blindness and the Perception of Race
Race is a complicated concept. For many, it’s often linked to skin color. But how do blind individuals perceive race, and what does this tell us about humanity as a whole?
Osagie Obasogie, a law professor at the University of California, conducted interviews with people who were blind from birth to learn their thoughts on race. Many of those he spoke with were offended by the idea that blindness made them less aware of race or less likely to be racist. They did not see blindness as a ticket to moral superiority.
To Obasogie’s surprise, many of his blind interviewees were more attuned to skin color and racial distinctions than sighted people, primarily because they had learned through social interactions that race was a significant issue for others.
Obasogie finds this insight about racism fascinating, suggesting that it goes beyond just the color of one’s skin. He discovered that race held just as much importance for blind individuals, with many describing their methods of identifying someone’s race before a conversation—or date—progressed too far. From reaching out to touch someone's hair to being warned not to rely on accents or speech patterns, many blind people have become just as fixated on identifying race as those who can see.
Obasogie discovered that the issue of race was highly divisive for those he interviewed. He concluded that blind individuals are neither more nor less racist than those with sight. However, without visual cues, race becomes solely a social matter for the blind.
In his book Blinded by Sight: Seeing Race through the Eyes of the Blind, Obasogie suggested that race has long been thought to be determined by sight. The notion of being 'color-blind' often implies ignoring race, but his research indicated the opposite. Based on his findings, Obasogie argues that it’s time to reconsider our society’s views on race, biology, and human differences.
2. The Complex Belief in Other Enhanced Senses
A study conducted by the Montreal Neurological Institute aimed to explore how blindness might enhance hearing and whether it also boosts musical ability. The findings showed that individuals who lost their sight at a young age had a superior ability to detect pitch changes. However, those who went blind later in life had similar results to sighted individuals. It appears that a younger brain is more adaptable, repurposing regions originally used for visual processing to enhance other sensory capabilities.
This differs significantly from the idea that blind individuals simply focus more on their other senses or that these senses become heightened. The research suggests that improvements in hearing or musical ability aren't guaranteed for all blind people and may not be something that can be trained or acquired.
A separate study conducted by Georgetown University Medical Center explored what happens in the brain's visual cortex when auditory signals are processed there. When blind participants listened to sounds through headphones, their visual regions activated. In contrast, the visual regions of sighted participants remained largely inactive during the same task.
In comparison to the brain's auditory processing center, the visual cortex is roughly twice as large and intricate. While blind individuals might seem to have sharper hearing, this is less about their auditory system and more about their brain reorganization, where the visual cortex is repurposed for new sensory functions.
1. Ghosts and Phantom Eye Syndrome
A lesser-known variant of phantom limb syndrome, phantom eye syndrome (PES), occurs in individuals who become blind due to the complete removal of one or both eyes. The Liverpool Ocular Oncology Center conducted a thorough study on PES, uncovering expected results. Participants, all of whom had lost an eye to cancer between 4 months and 4.5 years earlier, reported phantom sensations such as pain in the missing eye and visions of things that weren't actually there. Many described seeing fireworks or kaleidoscope-like lights, but notably, a significant number also experienced sightings of ghosts.
Some individuals with PES claimed to spot unfamiliar figures at the edges of their peripheral vision. One woman described waking up one night to see a ghostly figure standing near her bed, while another often saw a mysterious figure walking alongside him. A third woman reported seeing ghostly figures when it was dark. Additionally, one patient noted seeing people at the periphery of his vision, but they always vanished whenever he looked directly at them.
The question of whether the blind are more prone to seeing ghosts isn't new. A 1887 article from Chambers’s Journal of Popular Literature, Science and Art tackles this topic. The author argues that although he is certain ghosts don't exist, blind people are uniquely able to perceive them. Since, to a blind person, everyone appears as spectral, ghostly images, the ghosts seen by the blind must be just as real.
