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Module 1.4c

Figure 1.4-21
One skull, two minds
When an experimenter flashes PRACTICE
HE•ART across the visual field,
a woman with a split brain
verbally reports seeing the
word transmitted to her left Research Methods & Design
hemisphere. However, if asked
to indicate with her left hand (SP 2)
what she saw, she points to the
word transmitted to her right (5 minutes) Much of the research
hemisphere (Gazzaniga, 1983). on split-brain patients has been
“Look at the dot.” Two words separated by a dot
are momentarily projected. done on those with debilitating epi-
(a) (b)
lepsy. Point out to students that the
results of split-brain research may
be due in part to the condition of
the individuals’ brains after experi-
encing years of this disease. Could
the brain’s organization in such
individuals be due to epilepsy? Or
is the specialization of the brain the
“What word did you see?” or “Point with your left hand same in all people? This question
to the word you saw.”
Copyright © Bedford, Freeman & Worth Publishers.
(c) is difficult to answer without doing
experimental research comparing
their left hand to what they had seen, they were startled when their hand (controlled by the the split brains of epileptics to the
right hemisphere) pointed to HE. Given an opportunity to express itself, each hemisphere
indicated what it had seen. The right hemisphere (controlling the left hand) intuitively knew split brains of healthy participants,
what it could not verbally report. which would be unethical to do.
When a picture of a spoon was flashed to their right hemisphere, the patients could
not say what they had viewed. But when asked to identify what they had viewed by feeling
an assortment of hidden objects with their left hand, they readily selected the spoon. If the
experimenter said, “Correct!” the patient might reply, “What? Correct? How could I possi-
bly pick out the correct object when I don’t know what I saw?” It is, of course, the left hemi- ENGAGE 1.4-9
sphere doing the talking here, bewildered by what the nonverbal right hemisphere knows.
A few people who have undergone split-brain surgery have been for a time bothered by (15 minutes) Use Teacher
the unruly independence of their left hand. It was as if the left hand truly didn’t know what
the right hand was doing. The left hand might unbutton a shirt while the right hand buttoned Demonstration: Behavioral Effects of
it, or put grocery store items back on the shelf after the right hand put them in the cart. It was the Split-Brain Operation to provide
as if each hemisphere was think- Distributed by Bedford, Freeman & Worth Publishers. Not for redistribution.
students with a dynamic example of
ing, “I’ve half a mind to wear my Figure 1.4-22
green (blue) shirt today.” Indeed, Try this! the consequences of the split-brain
said Sperry (1964), split-brain sur- People who have had split-brain procedure.
gery leaves people “with two sep- surgery can simultaneously draw
arate minds.” With a split brain, two different shapes. M1.4c: Behavioral Effects of
both hemispheres can compre-
hend and follow an instruction to the Split-Brain Operation
copy — simultaneously — different
figures with the left and right
hands (Franz et al., 2000; see also
Figure 1.4-22). Today’s researchers
The Brain: Damage Response and Brain Hemispheres Module 1.4c 83

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The Brain: Damage Response and Brain Hemispheres Module 1.4c 83

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