Why is text less efficient than pictures? Because, it turns out, the brain
sees words as lots of tiny pictures. 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, our brains linger at
each feature, rigorously and independently verifying it before moving to the
next. So reading creates a bottleneck in comprehension. To our cortex,
surprisingly, there is no such thing as words.
That’s not necessarily obvious. After all, the brain is as adaptive as Silly
Putty. Given your years of reading books, writing email, and sending text
messages, you might think your 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, your brain will still stop and ponder the
individual features of each letter you read—and do so until you can’t read
anymore.
By now, you can probably guess why this might be. Our evolutionary
history was never dominated by books or email or text messages. It was
dominated by trees and saber-toothed tigers. Vision means so much to us
because 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. A lot of brain science now backs him up.
Vision is king from Day One
Babies come with a variety of preloaded software devoted to visual
processing. We can determine what babies are paying attention to simply by
watching them stare at their world. The importance of a baby’s gazing
behavior cannot be underestimated.
You can see this for yourself (if you have a baby nearby). Tie a ribbon
around the baby’s leg. Tie the other end to a mobile. At first she seems to be
randomly moving her limbs. Soon, however, the
infant learns that if she
moves one leg, the mobile turns. She begins happily—and preferentially—
moving that leg. Bring back the same mobile the next week, and the baby
will move the same leg. Show the baby a different mobile, and she won’t
move the leg. That’s what scientists found when they did this experiment.
The baby is paying the most attention to the visual aspects of the mobiles.
Since the mobiles don’t look the same, there’s not much reason to assume
they would act the same. Babies use these visual cues even though nobody
taught them to do so. This illustrates the importance of visual processing to
our species.
Other evidence points to the same fact. 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
nonhuman equivalents and seem to prefer the human faces. 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 of vision begins in the tiny world of infants.
It also shows up in the even tinier world of DNA. Our sense of smell
and color vision are fighting each other 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. Does this mean
that we’ll permanently lose our sense of smell or that our heads are no
longer getting bigger? Check back in several hundred thousand years. The
evolutionary forces that actively selected against smell are not still in full
force today. But what forces are replacing them is an active area of debate.
Whether
looking at behavior, cells, or genes, we can observe how
important the visual sense is to the human experience. Striding across our
brain like an out-of-control superpower,
giant swaths of biological
resources 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 over.
When it comes to applying this knowledge in your own daily life, is
there any point in trying to ignore the vision juggernaut? You don’t have to
look any further than the wine experts of Bordeaux for the answer.
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