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Your Blind Spot

Your Blind Spot

December 16, 2021

Did you know that your eyes have a blind spot? You might think your blind spots are on the sides of your head, but believe it or not, your blind spots are right in front of you. In the activity below, you’ll be able to actually see your blind spot.

Materials:
- Paper
- Black Marker

Procedure:
1. On a piece of paper, draw a plus sign and a dot. These should be 6-8 inches apart.

2. Now hold out the piece of paper in front of you with your arms.
3. Close your left eye and look at the plus sign with your right eye.
4. Bring the paper slowly towards your face as you look at the plus sign.
5. Eventually, the dot should vanish from the corner of your eye!
6. Repeat steps 2-5 but this time close your right eye and flip the paper over, so the dot is on the left.

What happened? The inside of your eye is covered in little things called photoreceptors. Photoreceptors detect light that comes into your eye and sends signals to your brain telling it what images to make. In order for your eye to tell your brain what it sees, it sends a signal through the optic nerve, which is kind of like a wire from your eye to your brain. The place where the optic nerve attaches to the eye, has no photoreceptors. So, if light hits that part of the eye, it has no idea what it’s seeing. This is only a tiny part of the eye, the size of a pin head, and we rarely notice it.

The first time, your brain erases the black dot and makes everything white, but with the second image, it erases the white dot and makes everything black. The cool thing about your blind spot is your brain knows it has a blind spot. Your brain looks at everything surrounding your blind spot and tries to guess what the blind spot would be. If it’s all white, then that blind spot is more likely to be white then bright red, right? Same with black, or any other color.