Hemispheric
Specialization I
Goals for Today’s Class:
Understand basic concepts of
neuropsychology
 Discuss lateralization/localization of
function in the human brain
 Study hemispheric specialization

Lateralization

The two different cerebral hemispheres
(halves of the brain)
DO differ

The hemispheres are
connected via the
corpus callosum
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

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.
Left visual field (LVF)
Left Hemisphere
Right visual field (RVF)
Right Hemisphere
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
Visual Field
R
L
Hemisphere
Function
L
Language
R
Spatial
Tasks
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
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.

words(40)
LVF
(10)
3-letters
6-letters
(20)
(20)
RVF
(10)
LVF
(10)
RVF
(10)
non-words(40)
3-letters
(20)
LVF
(10)
RVF
(10)
6-letters
(20)
LVF
(10)
RVF
(10)
Design:

IV1: lexicality


IV2: field of presentation


with 2 levels: word or nonword
with 2 levels: RVF or LVF
IV3: number of letters

with 2 levels: 3- or 6 letters
DV1: reaction time
 DV2: error rate in %

Instructions:
to begin a trial press the "space bar".
 Focus on X.
 respond as fast as possible, but also try to
avoid making errors.
