Hemispheric Specialization I

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Hemispheric Specialization I
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Goals for Todays Class

• Understand basic concepts of neuropsychology
• Discuss lateralization/localization of function
  in the human brain
• Study hemispheric specialization

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Lateralization

• The two different cerebral hemispheres (halves of
  the brain) DO differ
• The hemispheres are connected
  via the corpus
  callosum

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Common Myths

• There is a lot of pop psychology about
  hemispheric specialization
• Broad statements like the left brain is logical
  and the right brain is creative are almost
  always gross over-generalizations
• The two hemispheres do NOT operate independently
  they communicate constantly, mostly via the
  corpus callosum

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Lateralization

• different parts of the brain have different
  functions
• gt localization of function
• left and right hemispheres are specialized to do
  different things
• gt this is known as lateralization.
• contralateralitythe right half of your brain
  controls the left half of your body and vice
  versa.

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(No Transcript)
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Left visual field (LVF) Right visual field (RVF)
Right Hemisphere
Left Hemisphere
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Some True Differences

• Left Brain
• Controls the right side of the body
• Tends to be better suited for language
• Receives input from the RIGHT visual field

• Right Brain
• Controls the left side of the body
• Tends to be better suited to spatial tasks
• Receives input from the LEFT visual field

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Visual Field Hemisphere Function
L
R
Language
Spatial Tasks
L
R
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How can we study the differences between
hemispheres?

• Cut corpus callosum of severe epileptics
• L/R hemispheres will not communicate as quickly
  as those in normal people
• OR . . .
• We could restrict information to either the left
  or right hemisphere

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Overview of Experiment

• Q is the left hemisphere better-suited for
  language processes or not?
• Stimuli 40 words and 40 nonwords
• Half of the stimuli are 3 letters long, the other
  half 6.
• Half of the items are presented to the LVF/RH and
  half to the RVF/LH.
• Words randomly assigned to conditions.

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words(40) non-words(40)
3-letters (20)
6-letters (20)
3-letters (20)
6-letters (20)
LVF (10)
RVF (10)
LVF (10)
RVF (10)
LVF (10)
RVF (10)
LVF (10)
RVF (10)
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Design

• IV1 lexicality
• with 2 levels word or nonword
• IV2 field of presentation
• with 2 levels RVF or LVF
• IV3 number of letters
• with 2 levels 3- or 6 letters
• DV1 reaction time
• DV2 error rate in

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Instructions

• to begin a trial press the "space bar".
• Focus on X.
• respond as fast as possible, but also try to
  avoid making errors.