Depth perception is a key function of our vision and consequently our survival as humans. Without it we would not be able to judge distance of different objects, people, or even how deep something like a pool or a beaker is. Vision is a very complex combination of processes between the eyes, light, and the brain. That prompted me to think of some questions like, how do we use depth perception, and is it something we learn or something we are born with?

Let’s start with an example so that we are on the same page. Take a look at this picture of a road.

See how the sides of the road focus into a point in the middle of the image? We can see this through using depth perception. The farther away the road travels, the smaller the road becomes. It also looks like the sides of the road get closer together. The lines move to a point of reference called the vanishing point. Without the ability to perceive depth, this image would look flat. In other words, we would not be able to see in 3 dimensions. Study.com has a clear way of looking at a similar example using a railroad track.

Studies about depth perception have been conducted since at least the 1960’s. Probably the most famous experiment conducted is Eleanor J. Gibson and Richard D. Walk’s “Visual Cliff” experiment. Nature has the report about the experiment which placed infants and animals on a table. Half the table was one pattern while the other half of the table was a pane of glass that had the pattern placed on the floor. The results found that the animals and the infants would not cross over onto the glass side of the table. This can be seen in the video footage below.

http://https://www.youtube.com/watch?v=1VPaBcT1KdY

The studies like the visual cliff are reputable. Ethically, they are sound because no harm is coming to the infants or the animals involved in the testing. The experiment is manipulates the setting the test subjects are in by using the glass pane, but it is merely an observational test. Not much was known about how depth perception worked back then, seeing as the study of psychology was still relatively new at the time. There was clearly something significant going on which would make the experiment correct of at the least a false positive. The null hypothesis for the visual cliff experiment would be something along the lines of: The height level of the pattern of the floor has no effect on infants or animals perception. I think the experiment accurately refutes this null hypothesis.

One article I found on the topic explains the connection between our eyes and our brain involved in depth perception. “Two Eyes, Two Views: Your Brain and Depth Perception” is an article that discusses the stages of visual-image processing. Authors Vilayanur Ramachandran and Diane Rogers-Ramachandran write, “Visual-image processing from the eye to the brain happens in stages. Rudimentary features such as the orientation of edges, direction of motion, color, and so on are extracted early on in areas called V1 and V2”. This gives a look into the kind of process our brain works to build up our visual perception in layers. Kind of like laying a brick wall, different aspects of how we see the world build on each other to create the 3D perception we view the world in.

So that is a look into how it is we see the world we live in. It does leave some questions unanswered like what it would actually look like if someone could not perceive distance and depth properly. Who knows if that is a question we can accurately answer. Depth perception is a very unique part of human function that I feel is often overlooked.