Blind Spot of the Human Eye
Faith Clark
Mrs. Clark
Extra Credit 1
September 19th, 2016
Page 1 of 3
Blind Spot of the Human Eye
A blind spot or scotoma; is an area on the retina that does not have the receptor needed to respond to light. Because the human eye has a blind spot, the brain is left filling in what is there, by looking at the surrounding area. Although the eye sends the brain an accurate picture of what we see and what is going on in the world around us, there are limitations.
Although the blind spot takes away from our view of the world, there is a very good reason that we were created with one. The retina which is at the back of the eye and detects light, picks up information and then sends it to the brain, through the optic nerve… the problem with the optic nerve is that it needs a way to get out of the eye. That is why having a blind spot, is good. The route which it leaves from is the blind spot. Because we have two eyes, we do not notice our blind spots often. Each eye corresponds to the region of the retina where the optic nerve exits the eye. Because there are no photoreceptors associated with that region, objects obscured by the blind spot, remain unseen. In order to see where my blind spot was, I completed the following procedure...
- Hold the paper at arm's length and close your left eye. Focus on the square with your right eye, and slowly move the paper toward you. When the circle reaches your blind spot, it will disappear! Try again to find the blind spot for your other eye. Close your right eye and focus on the circle with your left eye. Move the paper until the square disappears.
- What happened when the circle disappeared? Did you see nothing where the circle had been? No, when the circle disappeared, you saw a plain white background that matched the rest of the sheet of paper. This is because your brain "filled in" for the blind spot - your eye didn't send any information about that part of the paper, so the brain just made the "hole" match the rest. Try the experiment again on a piece of colored paper. When the circle disappears, the brain will fill in whatever color matches the rest of the paper
- The brain doesn't just match colored backgrounds. It can also make other changes to what you see. Try drawing two filled-in rectangles side by side with a circle in between them. A few inches to the right of this, draw a square.
- Close your right eye and focus your left eye on the square. Move the paper until the circle disappears and the two separated bars become one bar. How did that happen? The circle in between the bars fell on your blind spot. When it disappeared, the brain filled in for the missing information by connecting the two bars!
Faith Clark
Page 2 of 3
Extra Credit
After doing this experiment on myself I discovered it was unsuccessful. After a few minutes of trying to determine where my blind spots were, I was still unable to get any results. Although the experiment did not work for me, I’m still aware of the importance of blind spots; even though this experiment did not work for it may be useful to others to figure out their blind spots.
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Faith Clark
Page 3 of 3
Extra credit
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