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A description of sight for the blind-since-birth (self.Blind)
submitted by big_wee_hag
I don’t know if this will be useful to anyone, but I’ve decided to put my insecurities aside and share it anyway. I have zero experience with blindness. I think about how vision works probably more than the average person does because I think it’s weird, that’s all. So without further ado, here is my explanation of what it’s like to be sighted.
Imagine that you’re holding a slim handle with one end resting against your abdomen and the other end pointed away from you. It’s the handle of an infinitely telescoping cane. It extends straight out until it hits something, so quickly that you can’t perceive its movement. It’s instantaneous, no matter how far away the object in front of you is. You can tell the quality of the thing it hits; you can tell the difference between a brick wall and a person, for example.
Now imagine you’re holding two of these things, one in each hand, side by side against your abdomen. They telescope out and one hits a person and the other hits a brick wall. So you can sense both of those objects at the same time.
Now imagine a thousand of these little telescoping canes extending out from a single point on your body, radiating out at different angles in a field the shape of a cone (that single point on your body being the point of the cone). You’d be able to sense everything that’s in front of you in that infinitely large cone. Remember, though, that each cane can only move in a straight line until it hits something, so if someone is standing directly in front of you facing you, you can’t sense the back of his head. Or, if you’re standing right in front of a brick wall, that wall is going to stop all of your canes and it’ll be the only thing you can sense.
So if you’re standing perfectly still, and you’re not moving your head, and you have a single eye that you’re also not moving, that’s kind of what vision would be like. The cane that moves straight forward from the center of your eye senses things the best; you can tell exactly what that cane is hitting. The more of an angle at which a little cane moves away from your eye, the harder it is to tell what exactly the cane is hitting (i.e. the edges of the cone are ambiguous). That’s why sighted people’s eyes move around constantly, and it’s nice to have a head that can swivel.
Having two eyes makes it easier to tell how far away things are. Your brain sort of automatically triangulates the distance when a cane from each eye hits the same object. Or something like that.
It’s not a perfect explanation, because there are some things that are translucent, meaning light can pass through them even though a physical object like a cane wouldn’t be able to. For example, glass. Your little eye canes can reach straight through a glass pane without being stopped by it. And there are other things, like fog, that a physical cane would pass straight through like air, but an eye cane would be stopped by.
The enormous drawback of sight is that it doesn’t work in darkness. If it’s completely dark, you have zero eye canes. There has to be a source of light somewhere for vision to work. The more intense the light, the better it works.
Color is much harder to explain. Color is a visual quality that all things have. If you have a flat, smooth wall and half of it is painted red and the other half is painted blue, a real cane wouldn’t be able to inform you of the difference. But a sighted person’s eye canes can tell the difference—at least in most people.
That’s all I’ve got. I hope that made sense and was interesting to somebody.
Imagine that you’re holding a slim handle with one end resting against your abdomen and the other end pointed away from you. It’s the handle of an infinitely telescoping cane. It extends straight out until it hits something, so quickly that you can’t perceive its movement. It’s instantaneous, no matter how far away the object in front of you is. You can tell the quality of the thing it hits; you can tell the difference between a brick wall and a person, for example.
Now imagine you’re holding two of these things, one in each hand, side by side against your abdomen. They telescope out and one hits a person and the other hits a brick wall. So you can sense both of those objects at the same time.
Now imagine a thousand of these little telescoping canes extending out from a single point on your body, radiating out at different angles in a field the shape of a cone (that single point on your body being the point of the cone). You’d be able to sense everything that’s in front of you in that infinitely large cone. Remember, though, that each cane can only move in a straight line until it hits something, so if someone is standing directly in front of you facing you, you can’t sense the back of his head. Or, if you’re standing right in front of a brick wall, that wall is going to stop all of your canes and it’ll be the only thing you can sense.
So if you’re standing perfectly still, and you’re not moving your head, and you have a single eye that you’re also not moving, that’s kind of what vision would be like. The cane that moves straight forward from the center of your eye senses things the best; you can tell exactly what that cane is hitting. The more of an angle at which a little cane moves away from your eye, the harder it is to tell what exactly the cane is hitting (i.e. the edges of the cone are ambiguous). That’s why sighted people’s eyes move around constantly, and it’s nice to have a head that can swivel.
Having two eyes makes it easier to tell how far away things are. Your brain sort of automatically triangulates the distance when a cane from each eye hits the same object. Or something like that.
It’s not a perfect explanation, because there are some things that are translucent, meaning light can pass through them even though a physical object like a cane wouldn’t be able to. For example, glass. Your little eye canes can reach straight through a glass pane without being stopped by it. And there are other things, like fog, that a physical cane would pass straight through like air, but an eye cane would be stopped by.
The enormous drawback of sight is that it doesn’t work in darkness. If it’s completely dark, you have zero eye canes. There has to be a source of light somewhere for vision to work. The more intense the light, the better it works.
Color is much harder to explain. Color is a visual quality that all things have. If you have a flat, smooth wall and half of it is painted red and the other half is painted blue, a real cane wouldn’t be able to inform you of the difference. But a sighted person’s eye canes can tell the difference—at least in most people.
That’s all I’ve got. I hope that made sense and was interesting to somebody.
Amonwilde 7 points 5y ago
In general, blind people, even the minority that are totally blind from birth, have a good idea of how sight works. After all, blind people live in a sighted society and, almost always, interact with sighted people daily. They know what sighted people can and cannot do and they know about the subjective sighted experience of color because they hear sighted people talking about it endlessly. They also know what culturally-ascribed moods or associations go with each color, such as red for warning and anger or blue for sadness or tranquility. That's because, again, sighted people constantly use color not only as a pragmatic indicator but also as metaphor. If you know English, you already know a lot about color associations. "I'm feeling blue." "She's green with envy." "They were seeing red after the meeting."
Color isn't that difficult to explain, at least in analogy to hearing.
Both light and sound can be conceived of as waves. Light is perception of radiation in the environment and sound is perception of the vibration or displacement of air molecules. As waves, the distance between the crests of the wave differs. In sound, we call this difference "frequency," as in how frequent we perceive the wave going up and down (oscillating). So if the frequency is high, the wave crests are close together. If the frequency is low, they are far apart. In hearing, we perceive these differences as a difference in pitch, like in this YouTube video:
https://www.youtube.com/watch?v=qNf9nzvnd1k
Color is the perception of frequency in the electromagnetic spectrum, a segment of which is visible light. So color can be explained by analogy as the equivalent of pitch in vision. Just as different entities in the environment create sounds at different pitches, which allows us to distinguish a violin from a sick cat (sometimes), perceiving colors helps to distinguish objects in the environment as well as properties of those objects.
Human cultures ascribe arbitrary names to certain frequency ranges, for example we call 606–668 THz "blue." There's nothing special about blue, though, it's just a range, and other cultures have chosen different ranges to name with different labels, though these days most of humanity seems to be converging on a common system.
Color isn't that difficult to explain, at least in analogy to hearing.
Both light and sound can be conceived of as waves. Light is perception of radiation in the environment and sound is perception of the vibration or displacement of air molecules. As waves, the distance between the crests of the wave differs. In sound, we call this difference "frequency," as in how frequent we perceive the wave going up and down (oscillating). So if the frequency is high, the wave crests are close together. If the frequency is low, they are far apart. In hearing, we perceive these differences as a difference in pitch, like in this YouTube video:
https://www.youtube.com/watch?v=qNf9nzvnd1k
Color is the perception of frequency in the electromagnetic spectrum, a segment of which is visible light. So color can be explained by analogy as the equivalent of pitch in vision. Just as different entities in the environment create sounds at different pitches, which allows us to distinguish a violin from a sick cat (sometimes), perceiving colors helps to distinguish objects in the environment as well as properties of those objects.
Human cultures ascribe arbitrary names to certain frequency ranges, for example we call 606–668 THz "blue." There's nothing special about blue, though, it's just a range, and other cultures have chosen different ranges to name with different labels, though these days most of humanity seems to be converging on a common system.
Negatratoron 2 points 5y ago
Very good description. One thing I want to add. While both pitches and colors differ by wavelength, there are differences in how they are perceived. The difference between red and green is more like the difference between hot and cold than between high pitch and low pitch. Ears contain a linear series of receptors that basically report to your brain the fourier transform of incoming waves, i.e. the wave in frequency space. Eyes, on the other hand, contain a smattering of four types of receptors, each reacting differently to different frequencies. Remember, Newton (I think it was Newton) discovered that there were colors beyond red and violet, while it is easily understood that the range of pitches extend beyond what we can hear.
big_wee_hag [OP] 1 points 5y ago
That explanation of color makes a lot of sense. That video was interesting! (I couldn't hear anything for 8 or 10 seconds on the low end, and on the upper end I couldn't hear anything past about 02:16 — I wonder if that's normal).
I just find it so fascinating how our senses work and how they feel subjectively, and I imagine it would be hard to understand a sense I didn't have. And I also think it's weird that vision is essentially flat. I see the world as a flattened plane, except that having two eyes allows me to understand that it isn't really flat at all.
Anyhow, thanks for indulging me, and I hope I didn't insult anyone with my unsolicited attempt at explanation. :)
I just find it so fascinating how our senses work and how they feel subjectively, and I imagine it would be hard to understand a sense I didn't have. And I also think it's weird that vision is essentially flat. I see the world as a flattened plane, except that having two eyes allows me to understand that it isn't really flat at all.
Anyhow, thanks for indulging me, and I hope I didn't insult anyone with my unsolicited attempt at explanation. :)
feelingc 1 points 5y ago
To me, your explanation was brilliant. I am sighted, and I have always wondered how sight could be explained to someone blind from birth. I suppose the true test would be whether a blind person found it helpful, but I thought it was a really good attempt.
I remember reading once about a young girl who was blind from birth, and how she was surprised that her mother (from across the room) could tell that her dress was too short. She thought, "So this, then, is sight. The ability to know this thing." I found that interesting, the gradually discovery of what "sight" meant.
I remember reading once about a young girl who was blind from birth, and how she was surprised that her mother (from across the room) could tell that her dress was too short. She thought, "So this, then, is sight. The ability to know this thing." I found that interesting, the gradually discovery of what "sight" meant.
Amonwilde 1 points 5y ago
The lowest humans can usually hear is around 20 Hz, and the highest is around 20000 Hz. So it's pretty normal if you can't hear up to 20-30 Hz, especially if you didn't pump your volume up, and then you won't be able to hear again past 18000 Hz, since YouTube only supports up to 18000 Hz. It's pretty normal to get some hearing loss, though, which might restrict your range somewhat.
feelingc 1 points 5y ago
You might also add that nearsighted people have shorter canes. Far sighted people have canes that are numb close to their bodies, but work fine after that. Astigmatism? Who knows? Don't understand it myself.
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