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baboons learned to recognize between
81 and 308 words, which they distinguished from more than 7,000 nonwords
with about 75 percent accuracy.
Rather than simply memorizing what
specific words looked like after many
presentations, monkeys came to realize that certain letter combinations distinguished novel real words from fake
ones, Grainger says. Baboons correctly
identified novel nonwords as bogus more
often than they incorrectly tagged actual
words seen for the first time as nonwords. Absent knowledge of letter patterns that characterize genuine words,
baboons would have mislabeled many
more unfamiliar words as nonwords,
Grainger holds.
The results set the stage for future
studies examining whether brain areas
activated while baboons identify words
and nonwords correspond to the area of
the human brain that’s stimulated during reading, Dehaene says.
Dehaene and his colleagues have
reported that, in people, reading selectively activates a left-brain region that
they call the visual word form area.
Responses of this neural tissue to
written material become stronger as
children get older and are related to
reading ability.
Reading and writing originated
roughly 5,000 years ago, long after
the modern brain had taken shape. So
In a new study, baboons pressed symbols on touch-screen computers to indicate
whether four-letter strings, such as vast and virt, were words or not. Correct
answers yielded food rewards.
neural terrain built for object and face
recognition was probably recruited for
the visual word form area as people
learned to discern letters and letter
arrangements in words, Dehaene says.
The new findings also fit with a proposal by evolutionary neurobiologist
Mark Changizi of 2AI Labs in Boise,
Idaho. He suggests that the shapes of
written scripts derive from the contours
of objects in natural scenes that human
brains’ visual systems home in on.
By grounding written letters in shapes
inherently preferred by the brain,
“writing systems could be more eas-
ily learned and were thus more likely
to survive and spread through a cul-
ture,” write neurobiologists Michael
Platt and Geoffrey Adams, both of
Duke University in Durham, N.C., in
a commentary also published in the
April 13 Science.
Back Story | READING ON THE BRAIN
Written language, and thus the ability to read, evolved relatively recently. So scientists
assume that the act of reading must co-opt brain areas that originally evolved for
other functions, such as vision and speech. Still, imaging studies suggest that learning to read may tune a chunk of the brain called the visual word form area to recognize the written word. Scans (left, brain viewed from below) have shown that looking
at words turns on a spot (red) in the left hemisphere. This patch of cells, in the fusiform gyrus, doesn’t respond as strongly to letters arranged nonsensically and ignores
words spoken aloud. “It’s picking up on statistical patterns and playing a huge role in
the information processing of visual words,” says neuroscientist Bruce McCandliss
of Vanderbilt University. But critics tend to emphasize other activities that turn on this
part of the cortex. Naming colors or deciphering Braille can also activate it —
suggesting that reading is just one use of this multifunctional area. — Devin Powell
