I’ve been interested in how our brain makes sense of the world for a long time, probably about as long as I’ve been an atheist. I think a lot of the supernatural experiences that people feel they’ve had are actually the result of perfectly natural phenomena which they’ve misinterpreted due to a lack of understanding of how their brain works. Everyone’s familiar with the various optical illusions which demonstrate how easily our eyes can be fooled, but most never stop to consider that it’s not our eyes that are being fooled; rather it’s our brains that are being fooled. Our eyes like all our other sensory organs are constantly transmitting a flood of information to our brain which, as it turns out, isn’t as good at taking it all in as we’d like to believe.
Yeah, we’ve all been told that the most amazing computer that has ever existed is the human brain, but that’s not really true. Our brains are pretty pathetic at processing all of the data they take in and so they compensate by cheating: taking shortcuts and ignoring a lot of the input. Keep in mind that it’s not just our senses that our brain has to worry about, it also runs all the bodily systems and is getting tons of feedback from internal sources which it has to respond to. Our lungs don’t inflate and deflate on their own, they’re controlled by a section of the brain. With all the crap it has to do every second of every day it’s really no wonder that our brain has to cheat a little when interpreting all the external stimuli. It doesn’t help that different parts of the brain handle different parts of the data processing.
For example, scientists have known for a long time that different regions of the brain are involved in the interpretation of color, shape and movement. What they didn’t understand is how the brain puts all of that together in a seemingly perfectly synchronized manner that allows us to recognize, say, a red ball rolling across a table for what it is. This is called the “binding problem” as in “how does our brain bind all the different data together to allow us to see a red ball moving?”
Now scientists at the California Institute of Technology researching this issue have come up with a very simple optical illusion that answers the question. Our brain cheats by making assumptions to fill in any gaps in data by drawing on past experience. They did a segment on NPR the other day called Tricks the Brain Plays that includes the optical illusion so you can try it out for yourself. It opens a small browser window that has a field of random red and green dots that are moving up or down the screen. Within 8 inches of the display you’ll think all the red dots are moving down and all the green ones are moving up, but if you shift your eyes to the left or the right of the image the direction of the dots will reverse. If you move back from your monitor you’ll realize that the truth is there are three columns of dots. The ones on the left and right have the red dots moving up and the green ones down and the middle column is the reverse.
The Illusion Explained: What’s happening is an example of a “binding problem” in the brain. Typically, color and movement are thought to be processed by different parts of the brain. But a red ball rolling across a table looks like a red ball rolling across a table because the brain puts the movement and color information together to form a coherent perception.
The brain is trying to do that in this illusion; it’s incorrectly binding color and motion so it can tell us that all the red dots are moving in the same direction throughout our “world,” in this case the animation display. The illusion breaks down if you stand several feet away from the monitor, and watch the illusion (a long mouse cable or a friend is necessary to do this.)
Even if you know ahead of time what the truth is that doesn’t stop your brain from cheating. It’s worse than that, though, some scientists have discovered that it’s entirely possible for you to completely miss something that happens right in front of you or that things have changed. Professor Daniel Simons of the Visual Cognition Lab at the University of Illinois has done some amazing experiments on what he calls “change blindness” and “inattentional blindness.” There was an interesting article printed earlier this month in The Daily Telegraph called Did you see the Gorilla? that talks about these experiments.
In one experiment, people who were walking across a college campus were asked by a stranger for directions. During the resulting chat, two men carrying a wooden door passed between the stranger and the subjects. After the door went by, the subjects were asked if they had noticed anything change.
Half of those tested failed to notice that, as the door passed by, the stranger had been substituted with a man who was of different height, of different build and who sounded different. He was also wearing different clothes.
Despite the fact that the subjects had talked to the stranger for 10-15 seconds before the swap, half of them did not detect that, after the passing of the door, they had ended up speaking to a different person. This phenomenon, called change blindness, highlights how we see much less than we think we do.
Working with Christopher Chabris at Harvard University, Simons came up with another demonstration that has now become a classic, based on a videotape of a handful of people playing basketball. They played the tape to subjects and asked them to count the passes made by one of the teams.
Around half failed to spot a woman dressed in a gorilla suit who walked slowly across the scene for nine seconds, even though this hairy interloper had passed between the players and stopped to face the camera and thump her chest.
However, if people were simply asked to view the tape, they noticed the gorilla easily. The effect is so striking that some of them refused to accept they were looking at the same tape and thought that it was a different version of the video, one edited to include the ape.
If you stop to think about it you can probably come up with some examples of both of these phenomena in your own life. My recent car accident is a perfect example of inattentional blindness as I never saw the oncoming car until just before it hit me as I was busy focusing on a jeep that was making a right turn onto the same road I was trying to turn left onto. I was so focused on the Jeep that I never saw the Sebring until it hit me.
So, yes, I believe that you think you know what you saw when you show up here and try to convince me that Elvis pulled up to you on a street corner and impregnated you with a mere kiss and I’m not in any way impugning your honesty when I question you on it. I just know that our brains experience a lot of things that aren’t true as well as misses a lot of things that are true. If more people would keep that in mind, so to speak, there’d probably be less of a market for the tabloids out there.
Oh, if you’d like to check out the video clips of Professor Daniel Simons’ experiments you can do so by clicking here.
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Posted on 06/17/2007 at 01:04 PM 
I’m sure most pet owners can back me up with this one.
Any lump of clothes, or bag or groceries convincingly turns into your pet when seen peripherally. Usually in some strange pose that causes you to glance over only to find out what it really is.
This visual goof is often so convincing that even if you look, identify the blob as what it really is, and look away you will still “catch your pet out of the corner of your eye” in the same location and pose seconds later.