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20 Cards in this Set
- Front
- Back
Define: Language
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A system of signs/symbols and rules that enable communication
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Define: Psycholinguistics
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‘Psychology of language’
Psychological studies of language processing |
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Define: Neuropsychology of Language
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Studies of language processing in relation to structure and function of brain
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The brain...
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Is not a homogenous mass – it has various function ‘modules’
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Wernicke's area is in the...
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Posterior section of inferior frontal gyrus (IFG) of dominant hemisphere
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Broca's area is in the...
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Posterior section of superior temporal gyrus (STG) of dominant hemisphere
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Language Laterizalation
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• Language is mostly processed in the left hemisphere (LH)
• LH is the dominant hemisphere for language • Handedness has an effect, but isn’t decisive • LH dominance: 95% of right-handed people, 61.4% of left-handed people |
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Wernicke-Geschwind model (1972)
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• Wernike’s area (posterior reception zone): receives input from sensory areas (visual, auditory, somatosensory), language comprehension
• Broca’s area (anterior expressive zone): receives signals from Wernicke’s area, speech production, sends signals to motor cortex |
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Problems with Wernicke-Geschwind model (1972)
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• Studies have shown other brain areas are also involved in language processing
• They are not restricted to the dominant hemisphere • Broca’s area may have a more general function that underpins language • Wernicke-Geschwind model is still a good model, but it needs updating |
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Hickok-Poeppel dual-stream model (2004)
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• Auditory fields located in STG bilaterally (although asymmetrically – LH still dominates)
• Ventral stream: mapping sound onto meaning; linked with sound-conceptual representation interface • Dorsal stream: mapping sound on to articulatory-based representations |
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Describe Wernicke’s Aphasia
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• Comprehension disorder
• Aphasia (from ancient Greek meaning speechlessness): an impairment in language production or comprehension as a result of brain damage • Type of fluent aphasia, meaning patients can talk without too much effort • Also known as receptive/sensory aphasia • Even patients make lots of nonsense when talking, the problem is mainly in comprehension, not in language production |
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Describe the implications of Wernicke’s Aphasia
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• Implications… Single dissociation – Wernicke’s area <-> language comprehension
• Wernicke-Geschwind model (the reception zone) |
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Describe the problems of Wernicke's Aphasia
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• Caused by damage to left posterior STG (area was later named after Wernicke)
• Great impairment in comprehending language (with no hearing loss) • Producing fluent language that makes little sense – patients don’t realise this |
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Speech Perception
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• Decoding speech sound
• Segmenting sound into phonemes (basic linguistic units which may have meaning) • Lexical identification (i.e. identifying spoken words) |
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Language comprehension involves
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Speech perception and comprehension
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Comprehension
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• Parsing (analysis of syntactical or grammatical structure of sentence)
• Semantic processing (understanding word meaning) • Pragmatics (intended meaning of language usage in various situations) |
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Difficulties with speech comprehension
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• Sound is brief, only one chance of hearing it
• Sound is continuous, yet we need to segment it into phonemes • …with all the noise, overlapping sound etc • …the same phoneme is slightly different acoustically between words (‘b’ in ‘ball’/’bell’/’bull’ is not exactly the same in the physical sound wave) • …other sensory information can help, or not (e.g. visual information, seminar 1 McGurk effect) • Despite how difficult it is, we’re quite good at it |
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Brain Strategy 1: Categorical Perception
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• A sound between two possible phonemes are perceived as one or the other, not anything unsure in between (seminar 2)
• If you hear something between /l/ and /r/, you will assign one of these two phonemes to the sound • This depends on language – in Japanese, /l/ and /r/ are not distinguished, therefore they become a single category (phoneme) • It also depends on speech speed • Brain doesn’t like ambiguity |
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Brain Strategy 2: Lexical Identification Shift
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• An ambiguous initial phoneme tends to be assigned to a phoneme category so that it forms a word rather than a nonword
• Being presented with sound varying between ‘tash’ and ‘dash’, you are more likely to hear ‘dash’ than ‘tash’ • This is believed to be an early perceptual effect, because rewards or penalties have no effect on it • Brain likes meaningfulness |
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Brain Strategy 3: Phonemic Restoration Effect
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• The listener can ‘perceive’ a phoneme which is missing from a sentence
• Listening to the sentence: It was found that the *eel was on the axle/shoe/table • You will hear different words depending on context (e.g. wheel, heel, meal) • We are not sure whether it is an early or a late process • Brain will fill in the gaps |