01 Feb The True Nature of Reality: The Third Dimension – 14

When we look at a flat sheet of paper, it has only two dimensions, height and width, but when we interact with the world there is an added third dimension, depth. Taking a photograph transforms a three dimensional scene into two dimensions, so how it is that we perceive three dimensions? What if our eyes were like cameras that could only capture a flat two-dimensional world? Well, our eyes actually work very similar to cameras, and it is the brain that creates the projected three-dimensional world we see. And while having stereoscopic vision certainly helps the brain better estimate the third-dimension, we can still perceive a three-dimensional world with only one eye open.

Because the third-dimension is manufactured in our brains, special drawing techniques can be used to fool the human eye into believing it is seeing a three-dimensional object while looking at a painting or piece of paper. Technology also allows color and light to be used to create 3D movies that help the brain manufacture a third dimension, allowing objects appear to move beyond the flat screen upon which they are projected.

There are other tricks that can be played on the brain, or more correctly, that the brain can play on us. In Idaho, there is a certain butte (an isolated hill with steep sides and a flat top) with a road that leads directly towards it. The road is higher in elevation than the butte, sits at an angle that still makes the butte visible, and ends at a drop off that leads down into a deep valley where the butte is located several miles away. There is a fascinating effect that happens when you walk down the long road towards the butte. When you are at the farthest point away from it (a place where it should appear smaller) the butte appears to be sitting on the horizon and looks massively big. As you travel down the road towards the butte, it should start to appear larger and larger, but when you get to the drop off and look down into the valley where the butte sits, it looks unspectacular and small. The change in apparent size is so dramatic, it seems like the massive butte has either completely disappeared or moved off far away into the distance.

Of course, the butte is always the same size, and under normal conditions the brain understands it needs to make the image of the butte appear larger and larger as we travel towards it, but there is an optical illusion that occurs from this particular road. Just as the moon looks enormous on the horizon and much smaller when it is up in the sky, the butte looks large because it appears to be on the horizon from one end of the road, but no longer sits on the horizon as you look down at the butte from the drop off at the other end of the road. Many people assume the moon looks larger on the horizon because it is closer to the earth, but that is not true. It is the brain that makes the moon and butte appear larger on the horizon because there are several things that give the brain the perspective to compare it in size (perhaps to trees, buildings, roads, etc.), but a moon up in the vast sky or a butte down in a deep valley give the brain a different perspective of the object we are viewing in relation to its environment, so it changes the size of the object we are viewing. In a very real sense, the brain can make things appear larger or smaller based on how it believes the object should exist in relation to all the other things it is viewing, even if if that change is incorrect or makes no sense at all.


Take some time to contemplate and think about the role the third-dimension (depth) plays in your daily life.

What activities in your daily life would be very difficult or impossible if you saw the world as flat and two-dimensional?

Do some research and find out what time the moon appears to be on the horizon at your location. Likewise, research a plausible time for viewing the moon when it is higher up in the sky. View the moon at both times and journal about your observations.

What was the difference in size between the moon seen on the horizon and the moon seen high in the sky? Hold your hand up towards the moon, with your arm extended fully, and make a circle with your hand that approximates the size to of the moon you are seeing. Draw these sizes in your journal and write down any thoughts about why they look look different.

Google “amazing 3d drawings which leap off the page“. Take a look at some of the images and write about what makes them appear to have three-dimensions.

If the brain can change the size of an object just because of the proximity of other unrelated objects, then what else can it change?

Is it possible to develop a mental safety net for recognizing errors in perception?

What will you do to remind yourself that some things you see may not be accurate, despite how convincing they appear?


Michael Ken