When I was a kid, I had a muscular length disorder in my eyes that kept them slightly out of sync - I can’t recall the exact name of the condition. It wasn’t “lazy eye” since it affeted both eyes equally. When I was 8 or 9, I had surgery to correct the length of the muscles, and since then, my eyes are in sync (you wouldn’t know I ever had a problem by looking at me).
But something I’ve wondered on and off throughout the years is if, during most of my developmental life, my brain learned to use my eyes without coordination, and so I failed to develop the necesary mental capabilities for binocular vision. Essentially, I have no idea if I have depth perception or not - how would you know?
I do feel like I have the option to choose which eye I’m looking out of at any given time - but the data from the other eye is of course still coming in, it’s just secondary. It’s hard to describe.
I can give a good estimation to the distance of objects - but if you close one eye, you can still tell about how far things are, right? Do you gain some sort of additional information if you open the other eye?
For that matter, when closing one eye, I don’t see any sort of perception shift, other than that the “secondary eye” is now seeing black. Unless the eye I close was the “primary eye”, in which case it shifts to the other. But I don’t suddenly lose the perception of 3d or something. But I have no idea if that’s totally normal, and everyone works the same way, or what. I have nothing to compare it to.
So, anyway, is there some objective, concrete way to test whether or not you have normal depth perception and binocular vision?
I think optometrists can tell you. Failing that, one way is to set two different objects at some randon distance apart on a table in good light. Then get back about 15 ft. or so, get down so that your eyes are on a level with the top of the table. Then have someone move them at your instruction until you think they are side by side.
I am the original blind in one eye and can’t see out of the other. My one eye is 20/20 (used to be 20/10) and my other is 20/200 with a severe astigmatism.
I do not have binocular vision.
Yet in driver training in high school I could line up the two blocks using string from 20 feet away as well as anyone in the class. How? Beats me I can just look at them and tell.
Where the lack of depth of field really shows up is in poor light. I recall once we my buddy and I were trying to snag some kabobs strung on wire off of the grill with only the light off the grille to go by. I had a pair of pliers in my hand and could not for the life me get the wire inside the jaws. It was a very Get Smart moment. Missed it by that much. My buddy commented that this was the only time he had every noticed that I did not have 3D vision.
I worked with a contact lens guy about 30 years ago to try and improve my vision. He hand ground a hard lens for me that brought my bad eye up to 20/70. He then tried lenses for a pair of glasses over the top. At one point he got my vision to 20/25 and all of a sudden I had 3D vision. he went to take the lens back and I said no. Holding it in front of my eye, I looked around the room. I almost got vertigo. Looking at the floor, my thought was Jesus, I am all the way up here without a seat belt?
The problem with the contact is that I could not get oxygen under the lens and after about 30 minutes, my eye felt like I was sticking a red hot poker in it. So no 3D for me.
Binocular vision vs monocular vision should be most noticeable when you are unfamiliar with what you are looking at. Far example, if you are looking at two cones sitting on the road, you can tell which is farther away both by where they are on the road and which appears smaller, since you know they are in fact the same size. If you are looking at two unfamiliar objects in a setting without visual cues you have no way of knowing if the objects are big and far away or small and close, or even which one is closer.
This seems to make sense for Rick. When in daily environments he can judge distance pretty well, but when he has no surrounding cues (dark and his target is hanging in the air rather than sitting on something) he has trouble. If it was some unfamiliar object rather than a wire he had a general idea of the diameter of it probably would have been even harder.
Yes, the armed services use machines like the optec 2300 to test the depth perception of aviation recruits. I would assume an ophthalmologist would have access to something similar.
I don’t know if this will make any sense, but I will try. With the 2nd lens in place all of a sudden the machine next to the chair looked so much closer than the chart of the wall. The round column that supported the machine looked so much more well I guess rounder is the word. When I looked down at the floor it looked so far away compared with my lap.
From what I can tell by using my two eyes, and some of what has been taught to me in a Vision and Robotics class, you can get very good depth perception using just one eye (or one camera). With one eye you need to move it a little so that your brain gets a different angle of the world. Your brain then uses this info so you can tell what is infront of something else.
Using two eyes just means you wont have to move your head to judge the depth of relatively close objects.
I lost the lens in my left eye when I was 5 via an accident (other than “wandering” the eye looks perfectly normal) . I have what I think is 3D vision in that I can catch balls and objects appear to have depth. The main limitation is when I am parking I have tough time telling exactly where the other car is when backing in and out and tend to be very conservative, in that I think I’m generally closer to the other car than I really am.
A few years ago I asked an opthamologist about this re having perceived 3D with one eye, and he told me my brain likely rewired itself because I was so young, if had lost the eye when older I’would have had a much tougher time adjusting.
IIRC binocular vision is mostly important for things fairly close to you - maybe within arm’s reach. I have no depth perception - average vision tests have demonstrated this! Your OP sounds a lot like how I see things. I tend to be somewhat clumsy when I go to grab things - I often hit things that I didn’t realise where closer to the object I want to pick up than I thought. It is also a little tough in the dark, but for most of the time, it doesn’t bother me at all and hasn’t prevented me from doing anything.
I’m probably not nearly as dramatic a case, but when I first got glasses, I noticed that my depth perception very noticeably improved. To me, the effect was like the whole world were suddenly seen through a View-Master… Things seemed to “jump out at me” more.
I think one can tell the distance with mono-vision because you have to focus on it, that focusing requires muscle effort, which you should be able to develop the ability to perceive the distance vs your focus.
So, if a person with normal vision closes one eye, does the world suddenly seem flat? And when they open it up again, suddenly everything seems 3d and deeper? Is it a dramatic transition?
Stereopsis is good out to about 11 meters, so since those objects were some distance away other depth cues start to play a larger role even though stereopsis is still usable by normal folks to some extent. Since you don’t have good stereo vision, you’re used to just relying on those other cues in the first place.
My six year old son fell face first off his bike this autumn, and smashed his face up. He had a blowout fracture of his orbit (he fell on the left side of his face and the air pressure broke the bone surrounding his right eye). As a result he had severe double vision which lasted about a month. Once a brain bleed had been ruled out, and the break had been diagnosed, he went through a battery of detailed eye tests to determine what was going on. They did several depth perception tests as far as I could tell - the first was very simple, with a book of fuzzy pictures and a pair of glasses. He was asked to touch the pages or pick things up and he consistently missed the book or pinched the air - really odd! Another one was done in a dark room where he faced a big black screen which had lines on it and pinpoints of red lights at the intersections of the lines. One light was illuminated and he was given a very cool green torch to shine on top of the light he saw. With one eye each he could get his light right on top of the point but with both eyes his torch beam landed inches away each time. Eeek. We were in the eye department doing tests for two full mornings, and it was on a production line system, going from technician to technician so I lost track of what we were testing, trying to keep a headachy, beaten up and fed up kid cooperating with the techs, so I think there were more tests that dealt with depth and binocular vision but I can’t remember now…
He couldn’t go to kindergarten for about three weeks, first because we couldn’t risk his face getting bashed again while the bone was healing, but mostly because he could not go up or down stairs without panicking because he saw four feet and numerous steps and didn’t know which was which. He had an upsetting (to me - I thought he’d stay like that forever!) habit of cocking his head to one side and closing one eye to eat or read or do Lego, as that resolved the image to one.
The doctor said that his eyeball had been pushed into a different postion and that either it would gradually ooze back (eww!) or that his brain would adjust for its new position. That seems to be what happened as over the course of a few weeks he saw objects closer and closer together until they were fully merged. He also would wake up seeing double for a few minutes each morning. After a month he was completely better, thank goodness.
I’m the author. You’re using the usual Magic Eye technique of of un-crossing your eyes and you get the intended perspective.
If you cross your eyes slightly, you’ll get the opposite perspective as described. I suggested the cross-eyed technique because it’s usually easier and the effect of the text seeming in the space in front of the screen is striking.
Depth perception really is a trick played by the brain on your consciousness using parallax, the difference of the views of your eyes. Using this pattern with your eyes crossed or uncrossed fakes the parallax and your brain plays along, so to speak.
I’ve read stories about people during their first time in planes or tall buildings thinking the things they saw on the ground through a window were “ants” rather than people. I don’t know if these stories are true, but I think it’s possible that if you never experience depth perception as a child, it might be hard or impossible to get it as an adult.