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News Release
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October 19, 1995
FOR IMMEDIATE RELEASE
CONTACT: Emil Venere
[email protected]
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Brain Injury Provides Strong Evidence for Mind's
Language Machinery
A Johns Hopkins University cognitive scientist, working with
Italian researchers, has used a highly unusual case of brain
damage to find key evidence supporting a widely accepted model of
how the human mind turns thought into language.
The findings came after two years of research on a 24-year-old
man who suffered brain damage, possibly resulting from
encephalitis. If the brain-damaged subject of the study had
spoken English instead of Italian, scientists might not have made
the discovery; the findings are directly related to the fact that
Italian, like a number of other languages, assigns feminine and
masculine gender to nouns, said
William Badecker, an associate
research scientist in the
Johns Hopkins Department of Cognitive Science.
After two weeks in a coma, the man seemed to recover completely,
speaking fluently and retaining most of his language capacity.
But he had a pronounced anomia, a condition in which the person
is unable to retrieve words.
For example, one-third of the time he was not able to remember
the names of familiar objects when shown photographs of them. He
also was not able to say anything about a word's form, such as
whether it rhymed with other words or how many syllables it had.
Scientists were startled to discover, however, that even though
the man seemed to know nothing about the word's form, nearly 100
percent of the time he knew whether it was masculine or feminine
in gender.
A scientific paper on the work, which refers to the man by the
pseudonym Dante, will be published in the November issue of the
international journal Cognition. The research provides important
evidence for the most widely accepted theory of how the brain
turns thought into words.
The mind does not simply retrieve information in one step, like a
person looking up words in a dictionary. Rather, it apparently
uses a complicated network of distinct modules to transform
thought into language.
In the Italian language, feminine words typically end in "a"
(such as casa, the word for house), and masculine words typically
end in "o" (such as caso,
the word for fate). But there are exceptions. "Problema" (the
word for
problem) is masculine, even though it ends in a, and "mano" (the
word for hand) is feminine, even though it ends in o.
However, regardless of whether a word fit the typical gender
pattern, Dante could identify its grammatical gender, even though
he could say nothing about what the word sounded like.
"To me, that was very exciting, because it immediately brought to
mind that model, and the kinds of predictions that the model
makes about the way the language system should break down,"
Badecker said.
The model maintains that the mind turns conceptual
representations into linguistic forms in two stages, referred to
as the lemma and lexemic levels.
When a person is shown a photograph of an animal, for example,
the brain selects a specific "lemma" for that particular word,
essentially retrieving a package of information about the word,
but without actually naming the word. The key point is that,
according to this model, the lemma includes the semantic and
grammatical features of the chosen word, including its gender, if
the language happens to assign gender to nouns, as Italian does.
But this package of information still has no word form. The lemma
level provides an "address" within the lexeme network,
essentially saying, "Go here to get the form," and the proper
word is retrieved, Badecker said.
This case is different than other studies of anomia, where people
could not remember words even though they could access many other
details about the objects they could not name. For example, if
shown a picture of a penguin, they could not come up with the
name of the animal, but they could come up with many general
facts and descriptions about it. Those examples, however, do not
provide clear evidence for the two-stage model because they fail
to show that the person has actually selected a lemma for the
object in the picture; they do not prove that the patients have
accessed grammatical information specifically related to that
word.
In Dante's case, there is a clear breakdown somewhere between the
lemma and lexeme levels, since he is able to get access to the
grammatical gender but unable to retrieve words; he has accessed
the lemma but then he cannot get to the appropriate addresses
where the specific word forms are located.
The fact that Dante spoke Italian was an essential component of
the research. "This is what allowed us to find the evidence for
the two-stage theory," Badecker said. Badecker wrote the
Cognition paper with
Raffaella Zanuttini, who is now on the
faculty of linguistics at Georgetown University, and Michele
Miozzo, a graduate student at Harvard University. Miozzo was a
graduate student at Hopkins and Zanuttini was a postdoctoral
fellow at the university when they started working with Badecker
on the research in 1990.
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