From the newsroom of the PhysOrg, Tuesday, August 1, 2006 .....



Sign language study reveals key finding about short-term memory




For decades, researchers have misunderstood a key aspect of short-term
memor y because of shortcomings in the way they compare the memory
capacity of deaf people who use American Sign Language (ASL) and hearing
people, according to a new study by a psychology professor at the
University of California, Santa Cruz.




Previous studies suggested that ASL users have smaller short-term memory
capacity than hearing people. But Margaret Wilson, assistant professor
of psychology at UCSC, found that short-term memory is equal when
laboratory conditions are carefully matched for the two languages.

Her findings appear in the August issue of the journal Psychological
Science in an article entitled "Comparing Sign Language and Speech
Reveals a Universal Limit on Short-Term Memory Capacity," coauthored
with Karen Emmorey, professor of speech, language, and hearing sciences
at San Diego State University.

Previous studies compared common English words and ASL signs, without
controlling for the amount of time it takes to ar ticulate the different
stimuli. A more recent study overcame that shortcoming by comparing
signed letters to spoken numbers with equivalent articulation times, but
it overlooked the fact that numbers have a unique superiority in
short-term memory and are problematic in comparative laboratory
experiments.

Wilson and Emmorey were careful to make sure subjects were exposed to
precisely matched sets of ASL and spoken stimuli because many factors
affect short-term memory, including duration, similarity, and
familiarity. They compared recall of spoken letters to ASL letters that
take the same amount of time to articulate. Controlling for those
elements revealed no differences in short-term memory capacity between
the two groups. "Our data show that short-term memory is in fact equal
for English and ASL," she said. "The time it takes to articulate the
to-be-remembered material is a universal constraint on short-term
memory."

Wilson's findings are significant because they suggest that universal
principles govern the way short-term memory works. "Short-term memory
isn't a single dedicated mechanism, it's a principle, and it works the
same whether it's the mouth or the hand that's moving," said Wilson.

Researchers studying short-term memory have long believed that spoken
language is unique, but Wilson's work since the early 1990s has eroded
that notion by replicating speech-based studies with ASL and
demonstrating that the same principles hold. "There does not appear to
be a dedicated mechanism for verbal speech," she said.

Wilson's latest work further debunks the notion that "speech is special"
and opens the door to new approaches and different laboratory protocols.


Source: University of California, Santa Cruz

From Psychosis-Deaf







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