Binocular vision

Two eyes see more than one

Introduction

The view of the world we see out of our right eye is slightly different from the view we see out of our left. The differences in the views allow us to perceive three dimensions.

Material

• a 3 x 5 card (A rectangular whitish card about 7.5 cm by 12.5 cm)
• colored pens in red and green

Assembly

Color one side of the card with red stripes.

Color the other side of the card with green stripes at right angles to the red stripes.

To Do and Notice

Hold the 3 x 5 card at arms length.

Look at one edge of the card with both eyes.

Notice that you can see both the red stripes and the green stripes at the same time.

Close one eye.

Look at the card as you rock it back and forth. Notice that you can see either the red stripes or the green stripes but not both at the same time.

What's Going On?

With both eyes it is possible to hold the card so that your right eye sees the red striped side of the card while your left eye sees the green striped side. You then perceive both the red stripes and the green stripes at the same time.

This shows you that each eye has a slightly different view of the world.

These different views can be used to give clues to the distance of an object.

Etc.

Close one eye.

Notice how prominent your nose appears.

Open both eyes. Notice that your nose is no longer prominently visible.

Close the other eye. Is your nose prominent.

I find it interesting that I notice different things when I close one eye.