Tag: blind

Seeing Your Own Eye Blood Vessels

By Anupum Pant

Blind spots are fine and I’ve known for years how to spot your own blind spot. You can make 2 spots on a paper separated by 4-5 inches, close your right eye and look at the right side spot with your left eye. If you do that and move forward or backward ( and rest at about 15 inches from the surface you drew on), you’d find a point where your left eye’s peripheral vision would not render the left side spot. You’d have found your blind spot.

But there is something more interesting, I never knew. You can actually see the blood vessels of your eye, with your own eye. Here’s how…

Take a sheet of paper (or card), and poke a pin hole in it. Then close one eye and holding paper close to your eye, jerk around the paper in little circles. At the same time, make sure you are looking at a bright white area through that hole. You could open up MS paint, make the whole canvas white and stare at it through the hole. Try to focus on the white screen and not the paper (or card)…

The video probably explains it better.

Human Echolocation – Seeing With Your Ears

By Anupum Pant

Bats can see, but Daniel Kish can’t. Due to Retinal Cancer (Retinoblastoma), Daniel has been completely blind since the age of 13 months. To save his life, both his eyes had to be removed at a young age. But, even with no eyes, he can see. He sees with his ears. People call him the real-life batman.

What? When Daniel was young, he started making a clicking sound with his tongue to understand his environment. Little did he know, at a young age, he had mastered Echolocation – A technique used by dolphins, and bats to navigate when there is no light. At the age of 11, only when a friend told him about Echolocation, did he realize what he was really doing.

How? By listening to the reflected clicking sound, Daniel is able to map the shape, dimension, depth and density of objects in his brain. Like we use light to see, he uses sound to create a 3D map in his brain. He has trained his visual cortex to process non-visual information. With this ability he is able to ride a bicycle around, effortlessly. Think about riding with your eyes closed. He does it everyday.

According to him, what he does isn’t rocket science. He thinks every one, if trained well, can do it. With a concern for blind people around the world who aren’t encouraged to use echolocation to move around, he started an organization where he teaches people how to do it. You can watch his TED talk here. [video]

Side note: In a Tamil movie, Taandavam, he was the one who taught Shiva to move around using echolocation.

If you think Daniel’s ability doesn’t talk enough about the amazing human brain. This video of David Eagleman talking about how our brain perceives the world, will probably make you appreciate it [the brain] more. Watch it till the end where he talks about these plug-in-brain devices.
In short, brain can learn to interpret various kinds of signals to produce an image.

[read more]

Bats Can See

by Anupum Pant

While every teacher around the world is busy teaching their kids that bats are blind, the contrary is actually true. Bats aren’t really blind and they can see pretty darn well even in low light. In fact, their eyes work better than our eyes do in a dimly lit environment (eg. Moon light).

None of the bats’ 1100 species are completely blind. Although, there are a few which depend heavily on a technique called echolocation to navigate around objects which are near, they still have to use eyes to see objects which are far away. Additionally, most bats like to hunt in complete darkness (to avoid competition from other birds), so they use echolocation during such times [because eyes need at least some amount of light to be present]. The daylight hours spent by them to groom or sleep don’t demand much of their visual skills, but that doesn’t make them blind.

One way in which bat’s vision is poorer than our visual ability, is that they can’t see colors like we do. Everything they see is in black and white. This disability, if you may call it one, is compensated by their ability to detect light waves whose frequencies lie beyond the human visible spectrum. Flying foxes, however, which are actually bigger bats, can see colors.

So, simply put, bats can see, but they don’t have to use their eyes to hunt or move around. This makes your teacher wrong when he/she says chides you with the phrase – “Blind as a bat”

Bonus Bat Facts

  1. Bats don’t carry rabies. However, like humans, the disease affects some bats.
  2. Apart from vampire bats found in Mexico, Central America and South America, no other bats suck blood.
  3. Bats hunt insects above your head, they aren’t interested in your hair or your eyes.
  4. Bats can catch insects with their tail or wing membranes.
  5. Fruit bats are also known as flying foxes, they eat fruits.
  6. Bats collectively eat tonnes of insects and protect our crops.
  7. Some bats eat fish and frogs.
  8. Bats’ dung, is rich in nutrients. It is mined from caves, bagged, and used by farmers to fertilize their crops.

Echolocation: A bat echolocates by sending out streams of high-pitched sounds through its mouth or nose. These signals then bounce off nearby objects and send back echoes. By “reading” these echoes with its super-sensitive ears, the bat can determine the location, distance, size, texture and shape of an object in its environment. In some cases, a bat can even use echoes to tell insects that are edible apart from those that aren’t. – [Source]