1. Hemispheric Specialization I

2. Goals for Today’s Class:
Understand basic concepts of neuropsychology
Discuss lateralization/localization of function in the human brain
Study hemispheric specialization

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

4. 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

5. Lateralization different parts of the brain have different functions
=> localization of function
left and right hemispheres are specialized to do different things
=> this is known as lateralization.
contralaterality—the right half of your brain controls the left half of your body and vice versa.

7. Left visual field (LVF) Right visual field (RVF)
Left Hemisphere
Right Hemisphere

8. Some True Differences Left Brain Right 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

9. Visual Field Hemisphere Function
Language
Spatial Tasks L R

10. 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

11. 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.

12. words(40) non-words(40) 3-letters 6-letters 3-letters 6-letters LVF
(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)

13. Design: IV1: lexicality IV2: field of presentation
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 %

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