Researchers explore whether
parrot has concept of zero
A bird seems
to have hit on a concept that eluded mathematicians for centuries—possibly
during a temper tantrum.
June 22, 2005
Special to World Science
Researchers are exploring whether a parrot
has developed a numerical concept that eluded mathematicians for centuries:
Oddly, it seems he may have
achieved the feat during a temper tantrum, the researchers say.
Although zero is an obvious notion to most of us, it wasn’t to people long
ago. Scholars say it came into widespread use in the West only in the 1600s by
way of India, which had it about a millennium earlier.
Yet Alex, a 28-year-old Grey parrot, recently began—unprompted—using the
word “none” for an absence of objects, according to Irene Pepperberg and
Jesse Gordon of Brandeis University in Waltham, Mass.
Alex thus possesses a
“zero-like concept,” they wrote in the May issue of the Journal of
Comparative Psychology, a research journal.
Years earlier, Alex had learned another meaning of “none,” as a lack of
information, they added. But his feat was to extend the concept to a context
involving numbers, during a test of his counting skills.
Alex’s apparent insight into nothingness doesn’t necessarily extend to
other arithmetical talents, though: the researchers found these to lag in some
respects behind those of young human children.
The scientists also said it will take further study to determine whether
Alex—who has been the subject of intelligence and communication tests
throughout his life—really understands zero.
Zero and none “are not identical,” Pepperberg wrote in a recent email. But
since Alex never learned “zero,” the researchers said, it’s impressive
that he started using a word he knew to denote something like it: an absence
of a particular number of objects.
Chimps and possibly squirrel monkeys show some understanding of zero, but only
after training, the researchers said. So Alex’s feat is the first time this
has been documented in a bird, “and the first time it occurred
spontaneously,” Pepperberg said via email.
But the insight didn’t come without a few bumps.
The story began when researchers began testing Alex to see whether he
understood small numbers, between one and six. Zero wasn’t expected of him.
The researchers would lay out an array of objects of different colors and
sizes, and asked questions such as “what color four?”— meaning which
color are the objects of which there are four.
After performed well on this, with no training, for dozens of trials, the
researchers recounted. But then he balked. Alex started ignoring questions, or
giving wrong answers, seemingly deliberately. He seemed to enjoy the
experimenters’ frustrated reactions, they said.
There was evidence, they added, that his stubornness stemmed from a boredom
with the the rewards he had been getting for right answers. The researchers
found some more interesting toys to give as rewards. After two weeks of
obstructionism, Alex grudgingly returned to the game, though he occasionally
seemed to lapse back.
One of these apparent lapses occurred one day when an experimenter asked Alex
“what color three?” Laid out before Alex were sets of two, three and six
objects, each set differently colored.
Alex insisted on responding: “five.” This made no sense given that the
answer was supposed to be a color.
After several tries the experimenter gave up and said: “OK, Alex, tell me:
what color five?”
“None,” the bird replied. This was correct, in that there was no color
that graced exactly five of the objects. The researchers went on to
incorporate “none” into future trials, and Alex consistently gave a solid
performance, they said.
“We cannot determine what cognitive process led to this behavior,” the
researchers wrote. “We suggest only that his action, occurring soon after a
period of noncompliance, resulted from a lack of interest in the given task
and was a possible attempt to make the procedure more challenging.”
In the future, the researchers said they want to test Alex for his ability to
add and subtract small quantities, including possibly zero.
As they try to determine whether Alex really understands zero, they will also
have to untangle the meanings of “none” and “zero.”
Merriam-Webster’s online dictionary defines zero, to begin with, as follows:
“the arithmetical symbol… denoting the absence of all magnitude or
quantity,” or “the number between the set of all negative numbers and the
set of all positive numbers.” The entry continues with several more
By contrast, the dictionary defines “none” entirely with the following
terms: not any, not one, nobody, not any such thing or person, no part,
Of course, what these words mean to the authors of a dictionary is one thing.
What they mean to a parrot is another.
A related question is the history of both words. “None” seems to also have
an older history than “zero.”
Zero was common in the West only from the 1600s on, though similar concepts
appeared earlier in fits and starts, according to J.J. O’Connor of the
University of St. Andrews in St. Andrews, Scotland.
In pre-zero times, O’Connor wrote in an online essay, some mathematicians
tied themselves in knots to solve problems that would have been much easier
with a zero. But ancient peoples as a whole probably didn’t think of it
because they didn’t need it: “If ancient peoples solved a problem about
how many horses a farmer needed,” he wrote, “then the problem was not
going to have 0 or –23 as an answer.”
“None” is considerably older than “zero” in Western cultures. It’s
related to a “neinn”—an early medieval Viking word—and is similar to
the still older Latin word “noenum,” meaning “not one,” according to
the Online Etymology Dictionary.
Whatever the etymological roots of Alex’s utterances, his performance has
its limitations, the researchers said. Several years ago, they tried to teach
him to recite a number line by presenting written numerals on their own,
without reference to groups of items. Alex performed rather poorly, unlike
normal schoolchildren, who can usually be fairly easily taught to recite their
numbers, like the alphabet, without this tangible reference.
Thus Alex’s apparent
insight into zero, if that’s what it is, doesn’t necessarily reflect
across-the-board mathematical genius. “Alex’s abilities might provide an
important parallel not with normal children but with those who have trouble
learning language and counting skills,” the researchers wrote.