521-Class 18

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Language impairments and their cognitive consequences[edit]

Readings: Poeppel et al. (2012)*; Lupyan & Mirman, (2012)

  • There is a lot of technical material in the Poeppel et al. paper. Don't sweat the details. Just try to get as much out of it as you can.

Poppel et al.

  • What is the "classical model" of neurobiology of language? (e.g. Wernicke-Lichtheim model, Geschwind model) Why is it no longer viable? What are the recent changes in theorizing?
  • What are some similarities and differences between spoken and signed languages mentioned by the authors?
  • What do the authors mean by the phrase "better resolution" in the recent changes of brain research on language?
  • What are the roles of the two processing streams--ventral and dorsal--in speech processing?

Lupyan & Mirman

  • What was the motivation for this study? How does the study extend the observations made by the Konstanz group?
  • What is the difference between low dimensional vs. high dimensional categorization trials? Why do the authors hypothesize that participants with aphasia would do poorly on one but not the other?
  • How did the participants with aphasia perform on the low/high dimension categorization tasks as compared to the control participants?
  • Are these results an example of an on-line or off-line effect?
  • What does this difference in performance tell us about the relationship between language and categorization? How does it link up to the paper in which people learned to categorize those blue aliens (Lupyan, Rakison, McClelland, 2007)?

Take home points[edit]

  • Aphasia is complex. There is no simple division into Broca's/Wernicke's/Receptive/Productive. Language is left lateralized, but many linguistic processes depend on both hemispheres.
  • Controlling for other disorders that go with aphasia, linguistic impairments tend to correlate with nonlinguistic impairments (categorization, sorting, abstract thought)
  • Naming difficulties tend to be specifically linked to problems with forming "low-dimentional" categories. Language impairments make it hard to isolate dimensions.
  • We can help establish causality by experimentally perturbing language (linguistic interference, tDCS)