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Ever heard the saying “Believe half of what you see and none of what you hear?” It’s a fun and useful rule of thumb. Who hasn’t seen or heard something outlandish every now and then? What may come as a surprise, though, is how accurate this statement is. Mounting evidence suggests that our brains are not as trustworthy as they lead us to believe.
Look at this screen. It’s bright and colorful (and is filled with awesome posts you should totally like and share). But what if I told you that what you see might not actually be there? Unknown to most, the human eye has a blind spot—a rather sizable one, in fact. The area where the optic nerve connects to the eye lacks light receptors, leaving it unable to gather information. As strange as it may seem, you have two gaping holes in your vision.
Close your left eye and look at the plus sign. Slowly move your head toward the screen, keeping your eye on the plus sign. When the elephant enters your blind spot, it will disappear.
Here is where it gets weird: take a look at the picture above and try the exercise. If done correctly, the elephant will disappear. This means that it has moved into your blind spot. But notice what you see in its place. This should be even more shocking than a vanishing elephant (which, I might add, does not happen every day). Your brain has filled in the gap with the color surrounding it.
Called filling in, this phenomenon explains why we do not notice our blind spots. The brain uses our surroundings to literally make up what we cannot see, covering the holes with its best guess as to what’s there. As crazy as the elephant example appears, this guesswork is amazing. Most people go through their entire life without noticing a single oddity. In fact, the brain does more than match background colors—every day it fills in complicated colors and patterns, flawlessly incorporating its predictions into the world before us. Just take a look at the picture below to see this in action.
Now cover your right eye and look at the small dot. Slowly move your head toward the screen. When the large circle enters your blind spot, the pattern will be filled in.
Filling in stands among the most incredible functions of the brain, but it comes with a troubling implication: we do not see the universe as it is. Our world is warped by the human experience, filtered by a brain that has evolved to re-imagine what our senses perceive. For all of humanity’s benefits, it comes at the cost of objectivity. Our eyes will never see the real world.
Two hundred and fifty years ago, German philosopher Immanuel Kant postulated that human existence is deceptive. Our perceptions are distorted by our humanity, he argued, and we will never see past the warped lens of the human experience. Centuries later, science has proven him right. Next time you see something incredible, remember to take your brain with a grain of salt.
So what do you think? Does this blow your mind? Please share your thoughts or other cool phenomena like this in the comments section below. As always, please like, share, or reblog this post if you enjoy it. That small click really helps me out. Be sure to check me out on Twitter and Facebook as well. Thanks for reading! Don’t forget to subscribe for new content every Wednesday! IT’S FREE!
Click here for last week’s post: If You Recline Your Airplane Seat You Are a Terrible Person!
Other related articles:
Why You Can’t Trust Your Brain (Psychology Today)
Find Your Blind Spots (Yale University) [Great how-to with cool examples]
Want to Achieve Your Goals? Science Says Stop Talking [More cool brain stuff]
Comment question of the week
Is your mind blown? What other cool things like this do you know about?
The Weekly Show 
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First, this post paints a very superficial and inaccurate picture of Kant’s epistemology. Kant didn’t think that our senses “sometimes deceive us,” due to physical limitations of sense organs.
He considered all perception–perception as such–to be infused with the fundamental, human conceptual content of the Categories, like space and time. This supposedly makes it impossible, in principle, to see things as they really are external to us, “in themselves.”
Second, how is one to “know” that his vision has “erred”? Presumably by reference to the same “fallible” vision. (!) (Even if one claimed a revelation to “correct the error” of one’s vision, how is one to know that the “revelation” is actually correct?)
The fact that one’s senses are limited in their capabilities and limited in a specific way by the blind spot in vision, does not make them untrustworthy or fallible. The fact that I can’t perceive radio waves does not mean that I can’t trust my vision within its limits. Nor does it mean that the objects of my vision are not external entities. My recognition of the fact that I don’t see in my blind spot presupposes the recognition that I do see in the rest of my field of view.
So long as your eyes are open, they give you what they give you, period. There was no possibility of a different perception, given the exact situation they were in. Hence, there is no basis for calling any perception an “error.” (An “error” presupposes an alternative to what was done.)
(I recommend Objectivism: The Philosophy of Ayn Rand and The Evidence of the Senses for more on this point.)
Hey, Sword of Apollo, thanks for the comment! It looks as though Reddit has chosen to focus on the philosophy at the end of the post. This was not intended to be the central theme, but oh well!
I disagree with some of your objections. First of all, the allusion to Kant is not a summary of his epistemology. It simply mentions one of his thoughts on the topic and draws a connection between the assertion—that we do not perceive things as they really are because our senses and understanding are infused with human conceptual content—and what filling-in suggests about our vision. I think this is both a faithful allusion to the philosopher and an appropriate connection.
In regard to your second point, the article is not meant to imply that filling-in is “wrong.” I instead use the phenomenon as an example of how our brains create what we see rather than relay objective information from our eyes. Were one to claim that filling-in is “wrong” that would, as you point out, imply that the rest of our vision is correct and create some logical problems. The article does not, however, make this assertion.
To address your third point, I do think that this revelation casts doubt on our senses. Since our brains filter and alter the information sent from our eyes, it is fair to call our senses untrustworthy within their limits.
Thanks again for the comment.
My favorite example:
http://perception.research.yale.edu/MIB-PercScotoma-2/MIB-PercScotoma2-Basic.swf
An example of a so-called perceptual scotoma.
The yellow dot isn’t flashing, but if you look at the center mark for a while it appears to do exactly that.
Very cool! Optical illusions like that are awesome. I’d definitely recommend you check out the ones I’ve linked to at the end of the post. That moment when things start moving/changing is always crazy (yet awesome). Thanks for sharing!
Reblogged this on CHANAPLUM.
Thanks for the reblog, chanaplum! Anything about blind spots or filling in that stands out in particular?
Interesting implications for “eye witness” accounts.
Agreed! It’s quite troubling to think of how much we rely on something that’s demonstrably error prone. There are other famous experiments and studies that cast even more doubt on our perceptions–I’d recommend you check out the Asch Conformity Experiments on YouTube. Great insight, and thanks for the comment!