Language and the Brain Understanding how language is represented and processed in the brain.
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Transcript of Language and the Brain Understanding how language is represented and processed in the brain.
Language and the Brain
Understanding how language is represented and processed in the brain
Psycholinguisics
The study of acquisition, storage, comprehension and production of language
Neurolinguistics: branch of psycholinguistics dealing with language and the brain
Cerebral cortex
Cerebral cortex: A one-quarter-inch thick membrane covering the brain– consciousness, thinking, learning, emotions,
language– Constitutes the difference between humans and
other animals
Corpus callosum: bundle of nerve fibers that connects the brain’s right and left hemispheres
LATERALIZATION
RIGHT HEMISPHERE
holistic reasoning music processing processing of non-
linguistic sounds visual, spatial
processing
LEFT HEMISPHERE
analytic reasoning temporal ordering arithmetic language processing
Each hemisphere specializes in diff. cognitive functions (referred to as lateralization)
Lateralization (Cont’d)
Most right-handersleft-hemisphere dominance for language
Left-handersgenerally less lateralized for language
Evidence of Lateralization:Language damage far more likely following left-hemisphere damage (70% vs. 1%)Dichotic listening testSplit-brain patients
Dichotic listening test
• Two different stimuli are presented simultaneously through earphones to the left and right ears
• The listeners are asked to say what they hear
threetwo
Which one do youthink is more
accurately reported?
Contralateralization
The connection between the brain and the body are almost completely contralateral
L s
ens
ory
info
rma
tion
R s
enso
ry in
form
atio
n
threetwo
The right ear advantage (REA)
Brain
BONES AND MUSCLES OF THE HEAD
threetwo
L
L earR ear
R
nonlinguisticsound
processing
languageprocessing
Listeners can identify linguistic stimuli more accurately when presented to their right ear.
two
The left ear advantage
Brain
BONES AND MUSCLES OF THE HEAD
Ha ha haZzzz
L
L earR ear
R
Listeners can identify nonlinguistic stimuli more accurately when presented to their left ear.
Riiing!
nonlinguisticsound
processing
languageprocessing
Split brain experiments
The hemispheres of the brain are connected by the corpus callosum
Corpus callosum severed to prevent severe seizures
In these experiments, patients are blindfolded and an object (let’s say a key) is placed in their right or left hand
Split-brain patients & language
BrainRL
key in left hand
Split-brain patients & language
BrainRL
key in right hand
Split Brain Experiments
KEY IN RIGHT HAND– Patient can name
object
KEY IN LEFT HAND– Patient unable to
name object
Broca’s area
FRONT
BACK
Angular gyrus
Language centers
Speech productionSyntactic info
Language comprehensionLexicon
Integrates visual & auditory infoCrucial for reading
Wernicke’s area
Language Disorders
A damage to one of these areas will affect the ability to produce/perceive language– Aphasia: – Broca’s Aphasia– Wernicke’s Aphasia
Broca’s area
Involved in speech production – motor programming for articulation
Involved in morphosyntactic analysis– Inflection– Structural complexity
Add grammatical refinements to content words selected in Wernicke’s area.
Sample speech: Broca’s aphasia•Examiner: Tell me, what did you do before you retired?•Aphasic: Uh, uh, uh, pub, par, partender,
no.•Examiner: Carpenter?•Aphasic: (Nodding to signal yes)
Carpenter, tuh, tuh, twenty year.
(Akmajian et al. 2001: p. 543)
Broca’s Aphasia and Syntactic Disorder Broca’s aphasics tend to omit inflectional morphemes
(-ing, -ed, -en, -s)—necessary for syntax Broca’s aphasics can’t determine grammaticality in
following sentences:– The boy ate it up.– * The boy ate up it.– * Boy ate it up.– The boy ate up the cake.
Broca’s Aphasia and Syntactic Disorder a. The mouse was chased by the cat. b. The cat was chased by the mouse Broca’s aphasiacs tend to interpret (a)
correctly, but they tend to give (b) the same interpretation as (a)
Our understanding of (a) and (b) is driven by syntax; a Broca’s aphasiac’s understanding is driven by semantics.
Wernicke’s area
Essential to language comprehension Involved in selection/evaluation of content
words (contained in lexicon)
Sample speech: Wernicke’s aphasia Examiner: Do you like it here in Kansas City? Aphasic: Yes, I am. Examiner: I’d like to have you tell me
something about your problem. Aphasic: Yes, I, ugh, can’t hill all of my
way. I can’t talk all of the things I do, and part of the part I can go alright, but I can’t tell from the other people. I usually most of my things. I know what can I talk and know what they are, but I can’t always come back even though I know they should be in, and I know should something eely I should know what I’m doing...
(Akmajian et al. 2001: p. 544)
Wernicke’s aphasia
Fluent, but their speech doesn’t make any sense.