Book 1, Question 24
Why Do We Have Two Eyes? The Secret of Depth!
Two eyes are better than one, and here is why. Each eye sees the world from a slightly different spot, a few centimeters apart, and your brain stacks the two views together to build depth and dimension. Two eyes also give you a backup if one is covered and a wider field of view. Animals show this too: predators like wolves often have forward-facing eyes for hunting, while prey like deer have eyes on the sides to watch for danger. Try the pencil-eraser experiment with one eye and then both!
From the book
Page from A Million Whys Book 1
More fun facts
- Depth perception is your ability to see things in three dimensions, including how big they are and how far away they are.
- Using two eyes together is called stereopsis. Some people call it stereo vision.
- The angle difference between your two eyes is tiny, but your brain uses it to work out distance.
- Most people have a dominant eye. That is the eye your brain relies on a little more.
- Your brain can switch which eye is dominant to fit the situation.
- Relying more on one eye saves your brain some work, so it does not have to keep up with both eyes equally all the time.
- Depth perception needs your eyes and brain working together, so anything that affects your vision can affect it too.
Sources: Cleveland Clinic, Cleveland Clinic
Questions kids ask
What is a dominant eye?
It is the eye your brain relies on most when you look at something. Most people have one.
What is depth perception?
It is seeing in three dimensions, which lets you tell how big things are and how far away they are.