Presentation on theme: "Language and Attention Chapter 20 Wednesday, December 3, 2003."— Presentation transcript:
Language and Attention Chapter 20 Wednesday, December 3, 2003
Features of Language 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 Chimpanzees cannot produce speech sounds because they lack the vocal apparatus. Chimpanzees (Washoe, Kanzi) and other apes can manipulate symbols. 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 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 Aphasia – a disorder of language. Wernicke’s aphasia – difficulty understanding written or spoken language. 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 Ideographs – characters that stand for an entire concept, representing a root word. Some writing systems have two ways of expressing language: 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 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 Prosody – musical elements of speech, including stress, pitch, rhythm. Affective components of language – convey attitude, value, emotion. Lateralized to right hemisphere. 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 Alexia and dyslexia – inability or difficulty reading. Dyslexia is congenital, alexia is acquired. Agraphia – inability to write. Word blindness – inability to comprehend words. Pure – alexia without agraphia.
Dyslexia May be congenital or acquired through brain injury. Inability to read despite normal IQ & cognition. Causes: 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.) More causes: 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 Left hemisphere: Language (spoken and written). Analytic, serial processing. Right hemisphere: Spatial processing. Face recognition. Some aspects of music. Both hemispheres work together.
Split-Brain Studies Surgery to sever the corpus callosum in epilepsy patients: 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 Matching and naming Right hemisphere cannot name things. Four picture identification Block designs Right hemisphere is better (also Braille). Figure copying – right is global. Music is complex Perfect pitch – localized to left hemisphere.
Handedness and Language Right handed people (95%+) have language localized to left hemisphere. Left handed people: 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 Some language processing does occur in right hemisphere: 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 The ability to select and differentially process simultaneous sources of information. 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? 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 Damage to right parietal lobe causes person to fail to acknowledge left visual field. Can involve failure to acknowledge left side of own body. Is it perceptual or attentional? Without input from right, left hemisphere may assume that what it sees is all that exists.
What is Consciousness? Bodily awareness Flow of attention Focus on internal processes Encoding in language The integrated results of unconscious processing Sense of “self”