Topic 7-language

• Phoneme: smallest unit of perceived speech

  • language-specific rules for combining phonemes (phonology)
• Morphemes: smallest unit that signals meanings

  • prefixes, suffixes, roots, or entire words
  • language-specific rules for combining morphemes (morphology)
• Words:

  • smallest stand-alone units of meaning
  • combinations of one or more morphemes
  • language-specific rules for combining words (syntax)
• Phrases:

  • organized grouping or one or more words
  • play a particular role in grammatical structure of a sentence
  • based on syntax
• Sentences:

  • a set of words/phrases that tells a complete thought
  • can express a statement, question, exclamation, request, command, or suggestion
  • can be combined to form larger linguistic units
• Generativity of language:

  • we combine words in novel ways to express novel ideas
  • language learning cannot be based solely on imitation, association, and reinforcemetn
  • language must be determined by an inborn biological program
• Grammar: rules for language structure, including:

  • morphology
  • syntax
• Semantics: how meaning is derived from morphemes, words, phrases, and sentences
• Phrase structure:

  • each word is assigned a role
  • Generative grammar: rules specify what orders and combinations these roles can occur in
• Structure:

  • Surface structure
  • phrase structure that applies to the order in which words are actually spoken
  • Deep structure
  • fundamental, underlying phrase structure that conveys meaning
  • Transformational grammar
  • rules that transform among surface structures having the same deep structure
• Ambiguity:

  • examples of language with multiple interpretations
  • Lexical ambiguity
  • when a word has two different meanings
  • Syntactic ambiguity
  • when same words can be grouped together into more than one phrase structure
  • Referential ambiguity
  • when same word/phrase can refer to two different things within a sentence (anaphors)
• Speech production:

  • fundamentally a motor act dependent on hierarchical planning
  • depends on pre-frontal areas
  • Broca's area
  • in left hemisphere only
• Broca's aphasia:

  • speech is laboured, slow, and nonfluent with awkward articulation
  • phenemic errors
  • written output shows same errors as speech
  • comprehension is relatively spared
  • not a motor problem
• Broca's aphasia and grammar:

  • problems with understanding and using syntax
  • greatest difficulty with verbs, articles, and pronouns
  • difficulty reading and producing function words
• Speech comprehension:

  • fundamentally a perceptual process
  • depends on the ventral 'what' stream
  • Wernicke's area
  • in left hemisphere only
• Wernicke's aphasia:

  • speech is phonetically and grammatically normal but meaningless
  • normal intonation
  • words used inappropriately, word salad
  • meaning expressed in a roundabout way
  • comprehension severely impaired
• Wernicke's aphasia cont'd:

  • problems translating auditory input into phonological forms that can then access semantics
  • problems with language comprehension
  • problems with understanding and using semantics
• Split brain studies:

  • left hemisphere can name objects, right hemisphere cannot
  • Broca's area in left hemisphere
  • right visual field information intact
• Right hemisphere and language:

  • Prosody
  • intonation, stress, and rhythm
  • used for emotional state, form, irony, emphasis
  • Aprosodia
  • difficulty processing prosody
• Aprosodia:

  1. Productive prosody
  2. monotonic, robotic speech lacking emotional tone; associated with damage to right hemisphere Broca's area equivalent
  3. Receptive prosody
  4. difficulty detecting and understanding emotional tone in speech; associated with damage to right hemisphere Wernicke's area equivalent
• Interactive language network:

  • localization and distribution of processing
  • Broca's area (syntax and production)
  • Wernicke's area (semantics and word perception)
  • Sensory cortices (auditory cortices)
  • Motor cortices (motor cortex)
  • Association cortices (semantics)
• Sources of information:

  • genes
  • past experience
  • internal state
  • environmental context
  • proximal stimulus
• Interactive activation theory: model of letter and word perception

  • integrates bottom-up and top-down processes
• McGurk effect: misinterpretation due to conflicting stimuli
• Garden path sentences: grammatically correct sentences that are easily misinterpreted at first read
• fMRI: measures changes in magnetization, using electromagnetic radiation and nuclear magnetic resonance
• Meaning in the brain:

  • concepts are represented by highly distributed patterns of activation across the brain
  • perceptual and motor brain areas involved in representing meaning
  • the association between concepts can be used to predict brain activation for those concepts