When it comes to vision, the human eye is quite mediocre, especially if we are comparing ourselves to our avian friends like hawks and eagles. Apart from not being able to spot a rodent on the forest floor from 200 feet up, our vision has a literal hole in it. Crazy right?
Our blind spot is basically a flaw of evolution. Anatomically, it is found over the optic disc, a region in our retinas where the nerve fibers bundle together to form the optic nerve. This simple exercise can reveal your blind spot.
Our blind spots are in our peripheral vision so for this exercise, cover your LEFT eye.
Now, with your uncovered right eye, stare directly at the black dot in the image below from about 2-3 feet away from your screen (best done on your computer or tablet) and gradually move closer to the screen.
Notice, at some point (usually around 8-12 inches away) the logo on the right will completely disappear from your peripheral vision. Pretty amazing right?
Now let’s examine this a little further because at this point you might have a few questions. How can this be? How could we have this hole in our vision and be oblivious to it? Well our brains are pretty spectacular. They fill in the gap with information based on our surrounding. So, repeat the exercise again with this image below. Notice that not only does the logo disappear, but the brain fills in the gap with pink. It intuitively does this to cover up the blind spot.
An even more impressive example of how our brains do this can be demonstrated with this last test. Follow the same steps and notice how as you draw closer to the screen, the yellow dot seemly turns red. As the yellow dot is brought into the blind spot, the brain literally makes up information based on the surroundings. It actually can’t see the yellow dot, but it determines that the most logical object in the blind spot is a red dot, given the surrounding red dots.
Isn’t that amazing? Share this with your friends and family and blow their minds too! It’s also a great way to get children interested in biology!