You Are Not So Smart: Why You Have Too Many Friends on Facebook, Why Your Memory Is Mostly Fiction, and 46 Other Ways You're Deluding Yourself Read Online Free PDF Page A

out in front of you and form two fists. Now bring them together so that if you were wearing rings they would be facing upward. Each fist represents a hemisphere. Your two hemispheres communicate with each other via a dense series of nerve fibers called the corpus callosum. Imagine when you made those fists you grabbed two handfuls of yarn—the yarn is your corpus callosum. In a corpus callosotomy (which is sometimes performed when a case of epilepsy becomes so severe and unmanageable that no drug will bring relief and normalcy) that yarn is cut. The two halves of the brain are disconnected in a careful way that allows the patients to live out their lives with as much normalcy as possible.
    Split-brain patients seem fine from the outside. They are able to hold down jobs and carry their weight in conversation. But researchers who have looked deeper have discovered the strengths and weaknesses of the separate hemispheres with the help of split-brain patients. Since the 1950s, studies with those who have undergone this procedure have revealed a great deal about how the brain works, but the insight most germane to the topic at hand is how quickly and unflinchingly these patients are capable of creating complete lies which they then hold to as reality. This is called split-brain confabulation, but you don’t have to have a split brain to confabulate.
    You feel like a single person with a single brain, but in many ways, you really have two. Thoughts, memories, and emotions cascade throughout the whole, but some tasks are handled better by one side than the other. Language, for example, is usually a task handled by the left side of the brain, but then bounced back and forth between the two. Strange things happen when a person’s brain hemispheres are disconnected, making this transfer impossible.
    Psychologist Michael Gazzaniga at the University of California at Santa Monica was one of the first researchers, along with Roger Sperry, to enlist the help of split-brain patients in his work. In one experiment subjects looked at a cross in the center of a computer screen, and then a word like “truck” was flashed on only the left side. They were then asked what they saw. Those with connected brains would, of course, say “truck.” Those with split brains would say they didn’t know, but then, amazingly, if they were asked to draw with their left hand what they had seen, they easily doodled a truck.
    Oddly enough, your right hand is controlled by your left brain and your left hand by the right. What the left eye sees travels diagonally through the cranium into the right hemisphere and vice versa, and these nerves are not severed when the brains are split. 1
    Normally this isn’t a problem, because what one side of the brain perceives and thinks gets transmitted to the other, but a split-brain can’t say what they see when a scientist shows an image to the left visual field. The language centers are in the other hemisphere, across from where the image is being processed. The part of their brain in charge of using words and sending them to the mouth can’t tell the other side, the one holding the pencil, what it is looking at. The side that saw the image can, however, draw it. Once the image appears, the split-brain person will then say, “Oh, a truck.” The communication that normally takes place across the corpus callosum now happens on the paper.
    This is what goes on in the world of a split-brain patient. The same thing happens in your head too. The same part of your brain is responsible for turning thoughts into words and then handing those words over to the mouth. All day long, the world appearing in your right hemisphere is being shared with your left in a conversation you are unaware of. At the biological level, this is a fundamental source of confabulation, and it can be demonstrated in the lab.
    If split-brain people are shown two words like “bell” on the left and “music” on the right and then asked to point