What is Depth Perception?

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  • Written By: Britt Archer
  • Edited By: Bronwyn Harris
  • Last Modified Date: 01 February 2020
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Depth perception is the ability of the human eye to see in three dimensions. It is often demonstrated with the measurements of length, width and height. For example, it is easy to recognize that an image is a photo, since cameras do not have accurate depth perception. That’s why when we take a picture, we know the person depicted in the image doesn't have a vase growing out of her head, but the resulting photo makes it appear that way. Optical illusions such as this illustrate how our minds perceive the visual imagery our eyes send to our brains.

Humans have a type of vision that is described as stereoscopic. The term stereoscopic comes from the Greek word stereos, meaning solid. Each eye sees an image that is separate from the image seen by the other eye. The brain processes the images and combines them into the final image seen by the brain. Eye depth perception is determined by how well both eyes function separately and how they function together to interpret images. It can be altered by changes to either eye.


One way we measure how a person sees the world is via a depth perception test. This test measures how you interpret binocular cues. These tests also measure monocular depth perception, or how you see the world when looking with only one eye. Of these cues, what allows humans to see and estimate distances are the ability of both eyes to focus on one object, the ability of the eyes to simply focus, and the ability to recognize shapes and sizes. These tell the brain where objects are in relation to other objects.

Not everyone sees optimally. People suffering from amblyopia, optic nerve hypoplasia and strabismus often have reduced depth perception. A person with an injury to one eye, or a person missing one eye, may not be able to tell where objects are in relation to others. Visual therapy may help improve these problems.

Depth perception plays an important part in many activities. Driving, sewing, threading a needle, watching 3D movies and even walking on uneven ground all require certain levels of depth acuity. People without functioning stereoscopic vision may not be able to perform these activities or may struggle with them. If you suspect a vision problem, speak to a licensed ophthalmologist or optometrist about testing your vision and the options available to correct or accommodate your vision needs.


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Post 7

When I decided to try progressive lenses instead of bifocals, I had a lot of trouble adjusting to these lenses. Progressive lenses don't have a line in the middle, like bifocals. The lenses are manufactured to correct for near sightedness, mid-line vision and far sightedness as you look through different parts of the lens.

It was really frustrating. I felt like I was going to fall when I went down stairs or on uneven ground. It seemed like things were out of focus and seemed to jump up at me.

I had to take great care when I drove, as it was difficult to focus.

It got better after awhile, but I think next time I will get bifocals.

Post 6

Depth perception abilities are part of the development of the eyes from the time of birth, along with coordination of the eyes and the brain. In order to have good depth perception, both eyes must be able to work together.

My sister has a child who had problems as a young child with difficulty in focusing. He had trouble with identifying shapes, letters and numbers.

Various treatments, including wearing a patch on one eye and wearing glasses helped, but he still has problems with sports and academics.

Post 5

@saraq90 - You may have just been right, not only in the lack of 20/20 vision affecting your depth perception but also your contact lenses can effect your depth perception.

I don't understand all the details, but I would talk to your contact lens prescriber about the different contact options that may even further improve your depth perception or maybe at least not hinder it as much!

Post 4

@saraq90 - I would imagine that those who are looking at this world with 20/20 vision as opposed to less accurate vision scores would probably have better depth perception!

However, I am not sure that even if you had contacts in and 20/20 vision with them in, if you would have the same depth perception as one without contacts. I think that is a good question!

I tried to play sports with glasses on, and like @ceilingcat discussed, glasses just seem to be the absolute worst (or maybe just different from contacts) for depth perception.

Post 3

I played sports and I always felt like I had horrible depth perception. I guess it could not have been too terrible as I probably would not have played for as long as I did as I would have continuously experienced various pelting of objects as I misjudged their depth.

The place where I felt the biggest difficulty with depth perception was in trying to bring the soccer ball out of the air from a punt or other type of long kick.

It makes sense that this would make the most difference in such a situation where the depth was large, but it seemed that the my teammates did not seem to have as much difficulty with bringing

the ball out of the air although it was at such a depth.

So although it is not as if I had no depth perception, I always wondered if the fact that I wore contacts and did not have 20/20 vision (even with contacts in) affected my depth perception.

Post 2

@ceilingcat - That must be kind of disconcerting for a second. I know depth perception plays a pretty important role in how we see the world.

In fact, when I was in college for photography, I used to like to play with depth perception. I enjoyed taking pictures of surreal subjects that would confuse the viewer a little bit. My favorite was to take a picture of two objects that were vastly different in size and make them look like they were the same size!

Post 1

I wear glasses most of the time, but sometimes I wear contact lenses. I've noticed that if I take my contacts out and then put my glasses on, my depth perception is messed up for a few minutes!

I think this has something to do with the fact that the contact lens sits directly on the eye, while glasses are positioned in front of the eye. Either way, it is super annoying!

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