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Plasticity
in the Language Domain
Language, gesture,
and the brain
Investigators: Aaron Newman and Nina Fernandez,
in collaboration with Ted Supalla and Elissa Newport
Project Overview
The ability to communicate
through language is specific to our species. However, the brain
mechanisms that have evolved in humans to permit and support this
ability are still unclear. We propose to study the cerebral organization
for sign language and non-linguistic gestures to shed light on this
question.
First, we will study the cerebral organization for American Sign
Language (ASL) in native signers, and compare it to that known for
English in native speakers. We will characterize the brain areas
that process simple signs as well as more complex grammatical structures
of ASL. Brain areas functionally specialized for grammatical analysis
should be activated similarly in English and ASL. However, additional
brain areas involved with visual-spatial processing may also contribute
to language processing in signers. Overall, these studies will determine
the brain systems that mediate language processing, independently
of the modality or typology of the language.
Second, we will compare the processing of sign language and non-linguistic
gesture. Both are produced in the visual-manual modality, and there
is evidence that sign languages may have evolved by systematizing
features of non-linguistic gesture. However, sign languages display
linguistic structure, whereas gestures do not. Thus, although sign
and gestures may share a network of brain areas involved in the
sensory-motor analysis of biological motion, areas that display
sensitivity to signs but not gestures will highlight the brain specialization
supporting language in the human species.
Related Publications
- For related publications, please visit our Publications page here .
Working memory in native signers:
Is
the working memory capacity limit of 7+/-2 an illusion?
Investigators: Angela Hauser, in collaboration with Elissa Newport, Ted Supalla, Nina Fernandez, and Matt Hall
Project
Overview (in progress)
Short Term Memory (STM) or the ability to successfully maintain
linguistic information over time is known to be limited in terms
of capacity. Since the seminal paper of George Miller in 1956, the
STM capacity limit has been defined as the 'magical number 7+/-2'.
Surprisingly, native users of American Sign Language appear to have
a smaller capacity limit of about 5 signs. Our work confirms such
a short STM span in signers, and show that this result cannot be
attributed to often cited factors such as greater complexity or
time of articulation for signs as compared to spoken words, or to
lower cognitive abilities in the deaf. Rather, our findings support
the recent proposal in the literature that the traditional 7+/-2
STM span in speakers is an exception. Our study establishes that
this exception is not due to the linguistic nature of the information,
and points to an advantage for auditory encoding in STM. Additionally,
we show that, despite significant differences in signed and auditory
STM spans, similar working memory resources are available to signers
and speakers during language processing. Thus, whereas STM span
measures are dependent on the language modality, memory capacity
during language processing is largely independent of the nature
of the language.
Related Publications
- For related publications, please visit our Publications page here.
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