Your Challenge: Find your blind spot!
What You Need
- Your eyes!
- Cut off the top inch or two off your piece of paper so that you have a rectangular strip of paper.
- Draw and color in a small circle in marker on the left side of your strip of paper.
- On the other end of the strip, draw an "X."
- Hold the paper strip about 20 inches away from your face.
- Close your right eye, and with your left eye, look at the "X" on the paper.
- Slowly bring the piece of paper closer to your face while still looking at the "X" with your left eye.
- At a certain distance, the circle will disappear!
- Now, repeat steps 4-8, this time closing your left eye and looking at the circle with your right eye. This time, the "X" should disappear!
How It Works
Your blind spot is the place where your optic nerve attaches to your retina on the back of your eye! Because of this, there are no light receptors in that spot. In this challenge, the circle or the "X" disappeared because they fell into your blind spot! Your brain fills in your blind spot to match its surroundings--in this case, that's the white of the paper! That's why you don't notice a hole in your vision when you're going about your everyday life!
- Octopuses don't have blind spots! Their eyes are constructed differently than mammalian eyes so that their optic nerve does not interfere with their retina.
- Your retina is about the size of a postage stamp and contains 130 million light-sensitive cells!
- Have your eyes ever turned red in a photograph? That is caused by light reflecting off of the blood vessels in your retina.
- Chameleons can look in different directions at the same time!
- Some animals can see colors that humans cannot! This is because they have more color vision cells than we do.