Brain Lateralization
One Brain or
Two?
Gazzaniga, M. S.
(1967)
• Left hemisphere – language,
logic, laughter
– Controls the right side of the
body
– Logical, verbal, sequential
– Positive emotions
• Right hemisphere –
– Control the left side of the body
– Spatial, emotional intuition,
music, “big picture”
(Neat fact: People with damage to
the left hemisphere may lose
their ability to speak but not sing
(a right hemisphere task). They
can redevelop language by
learning to sing everything they
want to say!)
D
D
D
D
D
D
D
D
1. What is the large composite
letter?
H (right brain active)
D D D D D
D
D
D
D
D
D
D
D
D
D
2. What is the small component
letter?
D (left brain active)
Which face looks happier to you?
FORK
SPOON
• When asked to SAY what they saw, they
answer __________________
– (spoon)
• When asked to pick up what they saw with
their left hand, they will pick up a ______.
– (fork)
Dr. J briefly flashed a picture of a key in the
right visual field of a split-brain patient.
The patient could probably
A. verbally report that a key was seen
B. write the word “key” using her left hand
C. draw a picture of a key using the left hand
D. none of the above
Answer: A
A split brain patient has a picture of a knife
flashed to her left hemisphere and that of
a fork to her right hemisphere. She will be
able to
A. identify the fork using her left hand.
B. identify the knife using her left hand.
C. identify the knife using either hand.
D. identify the fork using either hand.
Answer: A
What will happen as a neurosurgeon sedates the
entire right cerebral hemisphere of a patient
who is asked to count aloud with both arms
extended upward?
A. her left arm will fall and she will become
speechless
B. her right arm will fall and she will become
speechless
C. her left arm will fall and she will continue
counting
D. her right arm will fall and she will continue
counting
Answer: c
• People should typically recognize familiar words
more rapidly when spoken into their
__________ ear.
Answer: right
• People should typically recognize familiar
melodies more rapidly when played into their
________ ear.
Answer: left
Note: Not all people have such simple separations between hemispheres.
Women (more than men) tend to use both sides of their brain when
interpreting language.
Plasticity – the brain’s capacity to
reorganize
• Blind person’s sensory cortex for their fingers
may expand.
• In blind people, the visual cortex is activated
when they read Braille.
• In deaf people, some visual information is
process in the temporal lobe.
• Hemispherectomy – removal of an entire
hemisphere of cerebral cortex; if surgery
performed when young, other hemisphere takes
over