http://www.eurekalert.org/pub_releases/2001-08/cmu-tma081401.php

The medium and the message:
Eyes and ears understand differently,
Carnegie Mellon scientists report in
the journal Human Brain Mapping

PITTSBURGH- A new study by Carnegie Mellon University scientists shows that
because of the way the brain works, we understand spoken and written
language differently, something that has potential implications in the
workplace and in education, among many other areas.

In the first imaging study that directly compares reading and listening
activity in the human brain, Carnegie Mellon scientists discovered that the
same information produces systematically different brain activation. And
knowing what parts of the brain fire during reading or listening
comprehension affects the answer to one of the classic questions about
language comprehension: whether the means of delivery through eyes or ears
makes a difference. "The brain constructs the message, and it does so
differently for reading and listening. The pragmatic implication is that
the medium is part of the message. Listening to an audio book leaves a
different set of memories than reading does. A newscast heard on the radio
is processed differently from the same words read in a newspaper," said
Carnegie Mellon Psychology Professor Marcel Just, co-author of the report
that appears in this month's issue of the journal Human Brain Mapping.

Just said that the most recent methods of functional magnetic resonance
imaging (fMRI) were applied to measure brain activity during these
high-level conceptual processes. Rather than examining the processing of
single digits or words, his group is applying brain imaging to societal,
workplace, and instructional issues. "We can now see how cell-phone use can
affect driving, how reading differs from listening, and how visual thinking
is integrated with verbal thinking," Just said.

Using the non-invasive fMRI, scientists were able to measure the amount of
activity in each of 20,000 peppercorn-sized regions of the brain every
three seconds and create visual maps of how the mental work of thinking was
allocated throughout the brain from moment to moment. To the scientists'
surprise, there were two big differences in the brain activity patterns
while participants were reading or listening to identical sentences, even
at the conceptual level of understanding the meaning of a sentence. First,
during reading, the right hemisphere was not as active as anticipated,
which opens the possibility that there were qualitative differences in the
nature of the comprehension we experience in reading versus listening.

Second, while listening was taking place, there was more activation in the
left-hemisphere brain region called the pars triangularis (the triangular
section), a part of Broca's area that usually activates when there is
language processing to be done or there is a requirement to maintain some
verbal information in an active state (sometimes called verbal working
memory). The greater amount of activation in Broca's area suggests that
there is more semantic processing and working memory storage in listening
comprehension than in reading.

Because spoken language is so temporary, each sound hanging in the air for
a fraction of a second, the brain is forced to immediately process or store
the various parts of a spoken sentence in order to be able to mentally glue
them back together in a conceptual frame that makes sense. "By contrast,"
Just said, "written language provides an "external memory" where
information can be re-read if necessary. But to re-play spoken language,
you need a mental play-back loop, (called the articulatory-phonological
loop) conveniently provided in part by Broca's area."

The study doesn't attempt to suggest that one means of delivering

information is better than another, Just said. "Is comprehension better in
listening or in reading? It depends on the person, the content of the text,
and the purpose of the comprehension. In terms of persons, some people are
more skilled at one form of comprehension and typically exercise a
preference for their more skilled form where possible. It may be that
because of their experience and biology they are better and more
comfortable in listening or reading," he explained.

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Just carries out his research on the human brain through the Center for
Cognitive Brain Imaging at Carnegie Mellon (www.ccbi.cmu.edu). The language
comprehension project is funded by the National Institutes of Health.