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Language and Attention
Chapter 20
Wednesday, December 3, 2003
Features of Language
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Creativity – we create meaning by using
grammatical rules to generate new sentences.
Form – language is made up of smaller units
(phonemes, morphemes, words, sentences)
combined using rules.
Content – meaning can be abstract, context
independent, emotional.
Use – language has social purpose.
Animal Models of Language
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Chimpanzees cannot produce speech sounds
because they lack the vocal apparatus.
Chimpanzees (Washoe, Kanzi) and other apes
can manipulate symbols.
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Language development goes to a certain point
then stops – not fluent and creative like humans.
No evidence that animals form abstract mental
representations of meaning and think using
symbols.
Innateness of Language
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Language and sign language are both lateralized to
left hemisphere.
The planum temporale is larger in the left
hemisphere in most (67%) right-handers.
This asymmetry is present before birth.
Infants can differentiate speech sounds at birth –
critical period for recognizing phonemes for a
particular language.
Universal regularities in language acquisition.
Aphasias
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Aphasia – a disorder of language.
Wernicke’s aphasia – difficulty understanding
written or spoken language.
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Empty speech. Logorrhea (too much speech).
Broca’s aphasia – difficulty generating fluent,
grammatical speech (omit articles, adjectives).
Conduction aphasia – disconnection between
Broca’s & Wernicke’s area – cannot repeat.
Ideographs
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Ideographs – characters that stand for an
entire concept, representing a root word.
Some writing systems have two ways of
expressing language:
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Katakana (phonetic) vs kanji (ideographic).
Processing of kanji occurs in a different
region than processing of katakana, though
both are localized to left hemisphere.
American Sign Language
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Deaf people who know sign language show
deficits similar to Broca’s or Wernicke’s
aphasia – lateralized to left hemisphere.
Ability to move hands is not impaired – just
ability to move hands to produce language.
A hearing man who knew sign language
recovered both verbal and signing language
abilities together.
Aprosodia
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Prosody – musical elements of speech,
including stress, pitch, rhythm.
Affective components of language – convey
attitude, value, emotion.
Lateralized to right hemisphere.
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Damage to frontal cortex results in flat tone of
voice regardless of emotional state.
Damage to posterior areas of brain result in
inability to comprehend other people’s prosody.
Reading and Writing Disorders
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Alexia and dyslexia – inability or difficulty
reading.
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Dyslexia is congenital, alexia is acquired.
Agraphia – inability to write.
Word blindness – inability to comprehend
words.
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Pure – alexia without agraphia.
Dyslexia
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May be congenital or acquired through brain
injury.
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Inability to read despite normal IQ & cognition.
Causes:
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Deficient phonemic processing (speech sounds).
Visual processing defects due to abnormalities in
connections between visual and language areas.
Deficit in development of hemispheric dominance
– occurs in left-handers, letter reversals.
Dyslexia (Cont.)
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More causes:
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Cytoarchitectonic abnormalities, such as
incomplete segregation of layers in planum
temporale, clusters of misplaced neurons.
Inability to process sensory input with adequate
speed – magnocellular conduction too slow.
Hemispheric Lateralization
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Left hemisphere:
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Right hemisphere:
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Language (spoken and written).
Analytic, serial processing.
Spatial processing.
Face recognition.
Some aspects of music.
Both hemispheres work together.
Split-Brain Studies
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Surgery to sever the corpus callosum in
epilepsy patients:
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N.G.
Wada test – anesthetic injected in artery to
immobilize one hemisphere.
Techniques (e.g., Z lens) are then used to
present stimuli to one or the other
hemisphere, independently.
Tasks
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Matching and naming
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Four picture identification
Block designs
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Right hemisphere cannot name things.
Right hemisphere is better (also Braille).
Figure copying – right is global.
Music is complex
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Perfect pitch – localized to left hemisphere.
Handedness and Language
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Right handed people (95%+) have language
localized to left hemisphere.
Left handed people:
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70% have language in left hemisphere
15% have language in right hemisphere
15% have language in both hemispheres
With brain injury early in life, the other
hemisphere can take over language.
Right Hemisphere Language
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Some language processing does occur in right
hemisphere:
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Recognition of shapes of whole words.
Prosody of speech
Emotional content of speech
When language exists in both hemispheres
there is the potential for consciousness (self)
in both – P.S.
Attention
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The ability to select and differentially process
simultaneous sources of information.
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Can be focused upon a single modality or upon
specific items within a modality (e.g., a single
visual object).
Overcomes resource limitations related to
processing everything at once.
Processing advantages may result from
focusing upon specific sensory inputs.
What is Attention?
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Enhanced neural readiness to respond in areas
of the brain needed to perform a task.
Attention enhances detection when visual
stimuli appear in different locations.
Attention speeds reaction times in response
tasks.
Neglect Syndrome
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Damage to right parietal lobe causes person
to fail to acknowledge left visual field.
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Can involve failure to acknowledge left side of
own body.
Is it perceptual or attentional?
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Without input from right, left hemisphere may
assume that what it sees is all that exists.
What is Consciousness?
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Bodily awareness
Flow of attention
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Focus on internal processes
Encoding in language
The integrated results of unconscious
processing
Sense of “self”