Brain Rules: 12 Principles for Surviving and Thriving at Work, Home, and School (23 page)

1) Close your left eye, then stretch your left arm in front of you.
2) Raise up the index finger of your left hand, as if you were pointing to the sky.
3) Keep the arm in this position while you hold your right arm about six inches in front of your face. Raise your right index finger like it too was pointing to the sky.
4) With your eye still closed, position your right index finger so that it appears just to the left of your left index finger.
5) Now speedily open your left eye and close the right one. Do this several times.

If you positioned your fingers correctly, your right finger will jump to the other side of your left finger and back again. When you open both eyes, the jumping will stop. This little experiment shows that the two images appearing on each retina always differ. It also shows that both eyes working together somehow give the brain enough information to see non-jumping reality.

Why do you see only one camel? Why do you see two arms with stable, non-jumping fingers? Because the brain interpolates the information coming from both eyes. It makes about a gazillion calculations, then provides you its best guess. And it is a guess. You can actually show that the brain doesn’t really know where things are. Rather, it hypothesizes the probability of what the current event should look like and then, taking a leap of faith, approximates a viewable image. What you experience is not the image. What you experience is the leap of faith. Why does the brain do this? Because it is forced to solve a problem: We live in a three-dimensional world, but the light falls on our retina in a two-dimensional fashion. The brain must deal with this disparity if it is going to accurately portray the world. Just to complicate things, our two eyes give the brain two separate visual fields, and they project their images upside down and backward. To make sense of it all, the brain is forced to start guessing.

Upon what does it base its guesses, at least in part? The answer is bone-chilling: prior experience with events in your past. After adamantly inserting numerous assumptions about the received information (some of these assumptions may be inborn), the brain then offers up its findings for your perusal. It goes to all of this trouble for an important reason dripping with Darwinian good will: so you will see one camel in the room when there really is only one camel in the room (and see its proper depth and shape and size and even hints about whether or not it will bite you). All of this happens in about the time it takes to blink your eyes. Indeed, it is happening right now.

If you think the brain has to devote to vision a lot of its precious thinking resources, you are right on the money. It takes up about half of everything you do, in fact. This helps explains why snooty wine tasters with tons of professional experience throw out their taste buds so quickly in the thrall of visual stimuli. And that lies at the very heart of this chapter’s Brain Rule.

phantom of the ocular

In the land of sensory kingdoms, there are many ways to show that vision isn’t the benevolent prime minister but the dictatorial emperor. Take phantom-limb experiences. Sometimes, people who have suffered an amputation continue to experience the presence of their limb, even though no limb exists. Sometimes the limb is perceived as frozen into a fixed position. Sometimes it feels pain. Scientists have used phantoms to demonstrate the powerful influence vision has on our senses.

An amputee with a “frozen” phantom arm was seated at a table upon which had been placed a topless, divided box. There were two portals in the front, one for the arm and one for the stump. The divider was a mirror, and the amputee could view a reflection of either his functioning hand or his stump. When he looked at his functioning hand, he could see his right arm present and his left arm missing. But when he looked at the reflection of his right arm in the mirror—what looked like another arm—the phantom limb on the other side of the box suddenly “woke up.” If he moved his normal hand while gazing at its reflection, he could feel his phantom move, too. And when he stopped moving his right arm, his missing left arm “stopped” also. The addition of visual information began convincing his brain of a miraculous rebirth of the absent limb. This is vision not only as dictator but as faith healer. The visual-capture effect is so powerful, it can be used to alleviate pain in the phantom.

How do we measure vision’s dominance? One way is to show its effects on learning and memory. Researchers historically have used two types of memory in their investigations. The first, recognition memory, is a glorified way to explain familiarity. We often deploy recognition memory when looking at old family photographs, such as gazing at a picture of an old aunt not remembered for years. You don’t necessarily recall her name, or the photo, but you still recognize her as your aunt. You may not be able to recall certain details, but as soon as you see it, you know that you have seen it before.

Other types of learning involve the familiar working memory. Explained in greater detail in the Memory chapters, working memory is that collection of temporary storage buffers with fixed capacities and frustratingly short life spans. Visual short-term memory is the slice of that buffer dedicated to storing visual information. Most of us can hold about four objects at a time in that buffer, so it’s a pretty small space. And it appears to be getting smaller. Recent data show that as the complexity of the objects increases, the number of objects capable of being captured drops. The evidence also suggests that the number of objects and complexity of objects are engaged by different systems in the brain, turning the whole notion of short-term capacity, if you will forgive me, on its head. These limitations make it all the more remarkable—or depressing—that vision is probably the best single tool we have for learning anything.

worth a thousand words

When it comes to memory, researchers have known for more than 100 years that pictures and text follow very different rules. Put simply, the more visual the input becomes, the more likely it is to be recognized—and recalled. The phenomenon is so pervasive, it has been given its own name: the pictorial superiority effect, or PSE.

Human PSE is truly Olympian. Tests performed years ago showed that people could remember more than 2,500 pictures with at least 90 percent accuracy several days post-exposure, even though subjects saw each picture for about 10 seconds. Accuracy rates a year later still hovered around 63 percent. In one paper—adorably titled “Remember Dick and Jane?”—picture recognition information was reliably retrieved several decades later.

Sprinkled throughout these experiments were comparisons with other forms of communication. The favorite target was usually text or oral presentations, and the usual result was “picture demolishes them both.” It still does. Text and oral presentations are not just less efficient than pictures for retaining certain types of information; they are
way
less efficient. If information is presented orally, people remember about 10 percent, tested 72 hours after exposure. That figure goes up to 65 percent if you add a picture.

The inefficiency of text has received particular attention. One of the reasons that text is less capable than pictures is that the brain sees words as lots of tiny pictures. Data clearly show that a word is unreadable unless the brain can separately identify simple features in the letters. Instead of words, we see complex little art-museum masterpieces, with hundreds of features embedded in hundreds of letters. Like an art junkie, we linger at each feature, rigorously and independently verifying it before moving to the next. The finding has broad implications for reading efficiency. Reading creates a bottleneck. My text chokes you, not because my text is not enough like pictures but because my text is too much like pictures. To our cortex, unnervingly, there is no such thing as words.

That’s not necessarily obvious. After all, the brain is as adaptive as Silly Putty. With years of reading books, writing email, and sending text messages, you might think the visual system could be trained to recognize common words without slogging through tedious additional steps of letter-feature recognition. But that is not what happens. No matter how experienced a reader you become, you will still stop and ponder individual textual features as you plow through these pages, and you will do so until you can’t read anymore. Perhaps, with hindsight, we could have predicted such inefficiency. Our evolutionary history was never dominated by text-filled billboards or Microsoft Word. It was dominated by leaf-filled trees and saber-toothed tigers. The reason vision means so much to us may be as simple as the fact that most of the major threats to our lives in the savannah were apprehended visually. Ditto with most of our food supplies. Ditto with our perceptions of reproductive opportunity.

The tendency is so pervasive that, even when we read, most of us try to visualize what the text is telling us. “Words are only postage stamps delivering the object for you to unwrap,” George Bernard Shaw was fond of saying. These days, there is a lot of brain science technology to back him up.

a punch in the nose

Here’s a dirty trick you can pull on a baby. It may illustrate something about your personality. It certainly illustrates something about visual processing.

Tie a ribbon around the baby’s leg. Tie the other end to a bell. At first she seems to be randomly moving her limbs. Soon, however, the infant learns that if she moves one leg, the bell rings. Soon she is happily—and preferentially—moving that leg. The bell rings and rings and rings. Now cut the ribbon. The bell no longer rings. Does that stop the baby? No. She still kicks her leg. Something is wrong, so she kicks harder. Still no sound. She does a series of rapid kicks in sequence. Still no success. She gazes up at the bell, even stares at the bell. This visual behavior tells us she is paying attention to the problem. Scientists can measure the brain’s attentional state even with the diaper-and-breast-milk crowd because of this reliance on visual processing.

This story illustrates something fundamental about how brains perceive their world. As babies begin to understand cause-and-effect relationships, we can determine how they pay attention by watching them stare at their world. The importance of this gazing behavior cannot be underestimated. Babies use visual cues to show they are paying attention to something—even though nobody taught them to do that. The conclusion is that babies come with a variety of preloaded software devoted to visual processing.

That turns out to be true. Babies display a preference for patterns with high contrast. They seem to understand the principle of common fate: Objects that move together are perceived as part of the same object, such as stripes on a zebra. They can discriminate human faces from non-human equivalents and seem to prefer them. They possess an understanding of size related to distance—that if an object is getting closer (and therefore getting bigger), it is still the same object. Babies can even categorize visual objects by common physical characteristics. The dominance that vision displays behaviorally begins in the tiny world of infants.

And it shows up in the even tinier world of DNA. Our sense of smell and color vision are fighting violently for evolutionary control, for the right to be consulted first whenever something on the outside happens. And vision is winning. In fact, about 60 percent of our smell-related genes have been permanently damaged in this neural arbitrage, and they are marching toward obsolescence at a rate fourfold faster than any other species sampled. The reason for this decommissioning is simple: The visual cortex and the olfactory cortex take up a lot of neural real estate. In the crowded zero-sum world of the sub-scalp, something has to give.

Whether looking at behavior, cells, or genes, we can observe how important visual sense is to the human experience. Striding across our brain like an out-of-control superpower, giant swaths of biological resource are consumed by it. In return, our visual system creates movies, generates hallucinations, and consults with previous information before allowing us to see the outside. It happily bends the information from other senses to do its bidding and, at least in the case of smell, seems to be caught in the act of taking it over.

Is there any point in trying to ignore this juggernaut, especially if you are a parent, educator, or business professional? You don’t have to go any further than the wine experts of Bordeaux for proof.

ideas

I owe my career choice to Donald Duck. I am not joking. I even remember the moment he convinced me. I was 8 years old at the time, and my mother trundled the family off to a showing of an amazing 27-minute animated short called
Donald in Mathmagic Land
. Using visual imagery, a wicked sense of humor, and the wide-eyed wonder of an infant, Donald Duck introduced me to math. Got me excited about it. From geometry to football to playing billiards, the power and beauty of mathematics were made so real for this nerd-in-training, I asked if I could see it a second time. My mother obliged, and the effect was so memorable, it eventually influenced my career choice. I now have a copy of those valuable 27 minutes in my own home and regularly inflict it upon my poor children.
Donald in Mathmagic Land
won an Academy Award for best animated short of 1959. It also should have gotten a “Teacher of the Year” award. The film illustrates—literally—the power of the moving image in communicating complex information to students. It’s one inspiration for these suggestions.

Teachers should learn why pictures grab attention