- MONKEYS have a head for maths and can be taught to count, scientists
revealed yesterday.
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- Numeracy was thought to be a characteristic
that set humans apart from other animals.
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- But experts in New York have shocked
the scientific world by teaching two rhesus monkeys basic numeracy skills.
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- The apes, called Rosencrantz and Macduff,
were shown images in groups of one to four on touch sensitive TV screens.
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- They were rewarded with food if they
touched the objects in the right ascending order. The monkeys were then
told to touch two images in a row in descending order.
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- They knew one to four but worked out
five to nine. A researcher said: "Accuracy substantially exceeded
the level predicted by chance."
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- Monkeys Can Count
The Washington Post 10-23-98
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- Monkeys have an innate ability to conceptualize
numbers and can be taught to count at least to the number nine, according
to a series of groundbreaking experiments that promise new insights into
the evolution of intelligence. The research, in which monkeys played math-based
video games, challenges a longstanding view among many scientists that
humans are unique in their ability to grasp the concepts of number, numerical
order and basic arithmetic.
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- It stops short of concluding that monkeys
can add or subtract. But it indicates they can grasp the relatively sophisticated
concepts of "twoness," "threeness" and so on, and can
comprehend how those concepts relate to each other about as well as a human
3-year-old can.
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- Experts hailed the work as a major milestone
in understanding the intellectual ability of animals.
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- "When I heard about these experiments
I thought, 'Wow, these are the neatest animal representation experiments
of the decade,'" said Susan Carey, a cognitive scientist at New York
University. "It is very clever and convincing work."
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- Previous experiments had offered hints
of number awareness in nonhuman species, but some researchers suspected
that those animals had inadvertently been trained to give rote replies
or were just recognizing certain visual patterns, the way a person can
recognize the pattern of dots on a domino without actually counting them.
The new work is the first to indicate that animals can solve novel numerical
problems through an apparently genuine understanding that some numbers
are bigger or smaller than others.
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- The research may lead to the development
of better methods for teaching basic counting skills to cognitively impaired
people, researchers said. But it is primarily important to psychologists,
philosophers and theologians, who have long debated the extent to which
people and animals fundamentally differ ñ and especially the extent
to which animals can think.
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- "Mathematical thinking is considered
to be one of the most important and complicated abilities that humans have,
along with language," said Elizabeth M. Brannon, the Columbia University
graduate student who conducted the monkey experiments with Herbert S. Terrace,
a pioneer in animal cognition. "Now we can think about the rudiments
of number abilities as being shared by other animals."
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- The work appears in today's issue of
the journal Science.
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- For centuries, many philosophers and
other thinkers have believed that only humans can understand mathematical
concepts and operations, a realm of knowledge known as numeracy. That conclusion
was based in part on theological concerns about breaching the barrier of
intellect that supposedly separated people from "lower" animals,
and in part on anthropological evidence suggesting that numeracy is a cultural
construct ñ that is, it is conceived by and communicated among members
of a group and so requires the existence of language.
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- Yet many animals behave as though they
are able to perform computations. Some birds, for example, seem to use
vector analysis to navigate accurately over long distances. And many animals
seem to make decisions about where and how to forage based on calculations
about how much food is available in a given area and what the costs might
be of moving to another area.
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- In recent years scientists conducting
experiments on mice, parrots, dolphins, monkeys and other animals and found
evidence that these creatures can learn to count. In one test, a researcher
placed one or more eggplants behind a screen while a monkey watched, then
gauged the animal's reaction when the screen was removed to reveal either
the correct or incorrect total number of eggplants. Monkeys (and people)
typically stare longer than usual at something that violates their expectations,
and the monkeys stared longer when presented with the wrong number of eggplants,
suggesting they had recognized a mathematical error.
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- But it was also possible that the monkeys
had simply formed an image in their minds of the array of eggplants they
expected to see and were thrown off by the unexpected result without having
any real concept of number at all. Similarly, in experiments involving
pictures on a computer screen, it has been unclear whether animals understood
the difference between one item and three items or just noticed that in
the latter case more of the screen was covered by items ñ an exercise,
essentially, in measuring the total visual density of imagery on the screen.
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- In the new experiments, a pair of two-year-old
monkeys named Rosencrantz and Macduff sat before touch-sensitive computer
monitors that displayed four square "windowpanes." One pane always
contained a single item, such as a car; another pane contained a pair of
items, such as two apples; the third pane contained three identical items;
and the fourth contained four items. In a series of 35 trials in which
the types, colors, sizes and relative locations of the one-, two-, three-,
and four-item panes varied, the monkeys were trained to touch the one-item
pane first, then the two-item pane, then the three and finally the four.
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- The monkeys were rewarded with banana-flavored
pellets whenever they touched the panes in that ascending order and so
quickly learned how to "count" upwards to four. They did so irrespective
of item color, type or size (in some cases four items took up less space
than three), so their success apparently was due to counting and not to
a mere differentiation among visual patterns.
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- But had they simply learned how to count
"one, two, three, four," or had they actually grasped the arithmetic
concept of numerical order?
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- To find out, the team conducted 150 new
trials with five, six, seven, eight or nine items per pane. Even without
the reward system in place, the monkeys tapped the panes in ascending order
75 percent of the time, far more frequently than they would by chance.
Moreover, when shown nonconsecutive pairs of images, such as a pane of
five items and a pane of eight items, they tapped on five first, then on
eight.
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- "This demonstrates that the monkeys
were capable not just of the representation of numerical order, but also
of the abstraction of a numerical rule," namely "touch the lower
number of items first, then the higher one," Carey wrote in a commentary
that accompanies the research.
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- C. Randy Gallistel, a cognitive neuroscientist
at the University of California at Los Angeles, said the work shows that
monkeys do not simply see "twoness" or "threeness"
as independent properties of objects like "cowness" or "treeness,"
but as the numerically related concepts that they are. The monkeys are
not performing addition, Gallistel said, but they are demonstrating an
understanding of numerical order, which is a prerequisite to being able
to perform arithmetic.
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- "That is still an eye popper for
most philosophers and mathematicians," he said.
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- Research has shown that children have
a clear conception of numeracy by age 3 or so and a rudimentary understanding
even before that. But it remains unclear, Brannon said, whether monkeys
learn and perceive numeracy the same way toddlers do. Further experiments
may answer that question, she said, and could lead to an understanding
of how mathematical ability, and intelligence more generally, evolved.
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- The Washington Post, Oct. 23, 1998
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