2. Sign language
Sign language is a gestural language, produced by hand, face and more
generally body movement, that is mainly used by deaf people
Many different sign languages has emerged within deaf people
community, and a few ones have reached legal recognition
Lot of studies has been made about sign language, and more specifically
American Sign Language (ASL), that is derived from French Sign Language
Family (1)
3. Differences between sign languages
and spoken languages
Spoken languages are based on vocal production of sounds (speech) and
auditory system to communicate
Sign languages are based on hand movement, facial expression, and
visual system to communicate
Spoken languages are mainly one-dimensional : we can only make one
sound at a time, one after the other
Sign languages can use hands and face together, in a three-dimensional
world
4. Similarities between spoken languages
and sign languages
Both types of communication follow the same linguistic properties
They use letters and words as their basic components
Words are arranged following a grammar, and sentences communicate
feelings and thoughts
5. Neural basis for spoken language
Two main area are used by the spoken language recognition and
production : Wernicke’s area and Broca’s area (2)
6. Broca’s and Wernicke’s area
Wernicke’s area is a part of the brain located next to the primary auditory cortex.
It’s mainly used for language comprehension, both spoken and written
Deficiencies on this area cause fluent aphasia : the person can speak but with
unmeaningful speech
Broca’s area is a part of the brain located
This area is used for language production
Deficiencies on this area cause expressive aphasia : the person cannot produce
language, spoken or written
Both areas are located on the dominant hemisphere (the left one for more than 90% of the
population)
7. Neural basis for sign language
As the sign language use more visual recognition process, it might be
tempting to think that the right hemisphere is more used in the case of
native sign language speakers
But studies show that both sign and speech engage broca’s area (3)
Difference exists on the input and output of these areas (visual / auditory,
body motor / facial motor)
8. Existence of a pure semantic part of
the brain
As we can observe, parts of the brain are purely semantic : words are
abstracted to become unique entities, that can be translated into speech,
hand movements, or even in writing
Damaging on these specific areas will impair every kind of communication
between the person and the rest of the world
9. Usage of sign language to help
speech language pathology
Sign language is used by speech-language pathologists and early
childhood teachers to help the development of expressive language of
children who are slow to talk(4).
Beliefs are that those children can grow usage of language independently
of their problem, learn sign and then switch slowly to the oral mode.
