Physiological
Psychology
Sperry (1968)
Hemispheric disconnection
and unity in consciousness.
Plan for today
• Recap of Maguire (handout and quiz)
• Sperry (1968) Context, aim, sample,
procedure, results and conclusion
• Quiz to test knowledge of Sperry.
Recap handout for Maguire
Recap quiz for Maguire
Question 1 – The taxi drivers
were
A) Male, right-handed and aged 32-62.
B) Male, right-handed and aged 44-62.
C) Male, left-handed and aged 44-62.
D) Female and male, left-handed and aged
32-62.
Question 2 – What was the
average time that the taxi
drivers had been licensed for?
A) 1.5 years
B) 5.8 years
C) 10.1 years
D) 14.3 years
Question 3 – Which of the
following is false
A) Controls were all male.
B) Controls were all right-handed.
C) Controls were all healthy.
D) Controls attended the laboratory to take
part in the experiment.
Question 4 – The method was
A) Independent measures quasi
experiment
B) Repeated measure quasi experiment
C) Independent measures laboratory
experiment
D) Matched pairs laboratory experiment
Question 5 – Which of the
following is false
A) VBM is an objective technique to
examine the brain.
B) VBM identifies differences in grey
matter in different areas of the brain.
C) VBM is a 2D technique.
D) Grey matter is associated with higher
order thinking.
Question 6 - Which of the
following was not a control used
for the pixel counting technique
A) One person analysed the images.
B) The pixel counter did not know if the scan
belonged to a taxi driver or someone from
the control group.
C) Pixel counting is a well-established
technique to measure the brain.
D) The pixel counter did not know the
findings from the VBM technique.
Question 7 – Which two
results (for VBM) were found?
A) Significantly increased grey matter volume in
right and left posterior hippocampi for taxi
drivers.
B) No differences between hippocampi of taxi
drivers and the control group.
C) No differences between the brains of taxi
drivers and controls other than in their
hippocampi.
D) Significantly increased grey matter volume in
right and left posterior hippocampi for controls.
Question 8 – Pixel count
results found
A) No significant difference in overall
volume of hippocampi between taxi
drivers and controls.
B) Increased posterior hippocampi in taxi
drivers compared to controls.
C) Increased anterior and body
hippocampi in controls compared to
taxi drivers (especially the right).
D) All of the above.
Question 9 - Where did Maguire
et al conclude that we store
mental maps?
A) Body of hippocampus
B) Anterior of hippocampus
C) Posterior of hippocampus
BONUS POINT
What did Maguire et al say the LEFT
hippocampus stores?
Complements its partner by storing
memories i.e. people and events that
occur in the taxi drivers world (but not
necessarily integrating this information
into an existing map).
Physiological
Psychology
Sperry (1968)
Hemispheric disconnection
and unity in consciousness.
By the end of this session, you
will be able to;
• Describe the function of the corpus callosum.
• Identify the functions of the left and right
hemisphere.
• Describe the procedure and results of this
study.
• Be able to identify the actions of a ‘split brain’
patient when given different visual cues.
Some background
• Our brain is divided into two halves or ………..
• Each half is associated with different abilities.
Corpus
Callosum
Left
hemisphere
Right
hemisphere
Are you left or right brain
dominant?
To score …
Give yourself one point for each time you
answered "A" for questions: 1, 2, 3, 7, 8,
9, 13, 14, 15, 19, 20, 21.
Give yourself one point for each time you
answered "B" for questions: 4 ,5, 6, 10,
11, 12, 16, 17, 18.
Add all the points together …
The totals imply:
0-4: strong left brain
5-8: moderate left brain
9-13: middle brain
14-16: moderate right brain
17-21: strong right brain
Lateralisation of function
The two hemispheres have different
functions from each other.
The
brain
The Corpus Callosum
The Corpus Callosum is responsible for
communicating messages from the left
to the right hemisphere and vice versa.
The CC is made up of a think bundle of
nerve fibres called commissural fibres.
These are attached to both the R and L
hemisphere.
Right and Left hemispheres
and the Right and Left sides of
the body
Which
side of the
brain
controls
the left
side of the
body?
Which
side of the
brain
controls
the right
side of the
body?
Class brain
What is a visual field?
If you look
straightforward
everything to the left of
your nose is the left
visual field and
everything to the right is
your right visual field.
Left
Visual
Field
Right
Visual
Field
Visual fields – a little more
detail
HOWEVER!
It’s more complex
than right eye -> left
hemisphere and left
eye -> left
hemisphere.
Information from
both eyes goes to
both hemispheres.
EXAMPLE
Left
side
Right
side
Left
hemisphere
Right
hemisphere
(Language)
(drawing)
Left
Visual
Field
Right
Visual
Field
Humans
are …
crosswired
Complete brain hemisphere
and visual fields worksheet
What do we know about
epilepsy?
Symptoms can range from;
Brief loss of consciousness  severely
thrashing the legs and arms
uncontrollably (Grand Mal).
What is the cause?
Abnormal firing of electrical impulses
throughout the brain which interrupts
normal brain patterns.
During a seizure, electrical impulses pass from one
hemisphere of the brain to the other.
How (using what we have learned today)
might we be able to stop this?
Cut the Corpus Callosum
This procedure is known as a Split Brain Surgery.
(Is carried out as a last resort when medication
has failed).
The study
AIM - To study the effects of hemispheric
disconnection in split-brain patients and to
show that each hemisphere has different
functions (lateralisation).
Participants - 11 ‘split-brain’ patients who
had undergone surgery (hemisphere
disconnection) for epilepsy – compared
to ‘normal’ group.
Sperry’s apparatus
Based on Overhead
Projector.
Visual apparatus and
procedure
Participants had one eye
covered and asked to stare at a
point (fixation point) on a
projector screen.
Information (picture/word/symbol)
was flashed to either the left
visual field (LVF) or right visual
field (RVF) for 1/10th second.
WHY??
CONTROLS?
Tactile apparatus and
procedure
Below the screen was
a gap so participants
could be handed
objects or reach into a
‘grab bag’ and touch
objects but could not
see the objects or
his hands.
CONTROLS?
Controls
•
•
•
•
The fixation point.
Image flashed for 0.1 seconds.
Always had one eye covered.
Standard pictures/words/symbols
shown to each participant.
• Participants can’t see their hands.
• Same experimenter used.
Procedure
So the participants completed various
visual and tactile tasks (with the
experimenters attempting to see how the
two hemispheres functioned).
Participants remained in silence during
trials unless asked question by
experimenter.
WHY?
The study
• Independent
Variable?
• Dependent
Variable?
• Methodology?
• Hemisphere
disconnection (or
not).
• Performance on
visual (sight) and
tactile (touch) tasks.
• Quasi-experiment
(no control over IV)
and case studies.
Role of right and left hemisphere
Use your LEFT and RIGHT signs in
response to the following questions
….
LEFT
RIGHT
Language is processed in
which hemisphere?
LEFT
The right visual field is
controlled by which
hemisphere?
LEFT
Information from the left hand
is sent to which hemisphere
for processing?
RIGHT
If a patient had a seizure in their
left hemisphere, which side of the
body might be in danger of
paralysis?
RIGHT
Information from the right hand is
sent to which hemisphere for
processing?
LEFT
Information from the left visual
field is controlled by which
hemisphere?
RIGHT
Left handed people tend to be
which hemisphere dominant?
RIGHT
Video of split brain patient
https://www.youtube.com/watc
h?v=lfGwsAdS9Dc
Different tasks – Visual and
Tactile
1)
2)
3)
4)
5)
Recognising pictures
Matching pictures
$ and ?
Composite words i.e. KEY CASE
Identify objects in hand or find from
grab bag.
6) Dual processing task.
Instructions for task
You will be given a paragraph explaining
1 method out of the 6.
In pairs, you have 10 minutes to do two
things
1) Prepare and learn the actions to do a
role-play of procedure and results.
1 person is Sperry
1 person is the split-brain participant
Instructions for task
2) Prepare an A3 poster (include pictures)
to show the procedure and results.
As each pair presents their poster and
role-plays their procedure and results –
the rest of you can complete your
procedure and results handout.
Visual - Recognising
pictures
Stimulus flashed to left side of screen
Then flashed to right side
P doesn't recognise he has seen it before.
If stimulus was flashed to right side again,
participant responded as if he had seen it
before.
Each hemisphere has its own memories separate consciousness
Visual - Matching
pictures
Picture projected to Right Visual Field (goes to Left Hemisphere)
P can talk and write about it BUT…
If the same picture projected to Left Visual Field (goes to Right
Hemisphere)
P says he saw nothing or just a flash of light.
BUT if you then ask the same participant to use his left hand (controlled
by Right Hemisphere) to pick up a matching object from a grab bag, he
will pick up the object that he has just said he didn’t see.
What does this tell us about the right hemisphere?
EXAMPLE
RVF
LVF
What did you see?
???????
Left
Hemisphere
Right
Hemisphere
Can you pick out
(with your left
hand) the object
that you saw?
RVF
LVF
What did you see?
A happy face!
Left
Hemisphere
Right
Hemisphere
Can you pick out
(with your right
hand) the object
that you saw?
??????
Visual - $ & ? signs
If a $ is flashed to the Left Visual Field
and a ? to the Right Visual Field ….
The participant will draw (using the left
hand out of sight) the $ shown to the Left
Visual Field but if asked what they had
drawn would name the stimulus
presented to their Right Visual Field – the
?
$
?
LVF
RVF
What did you see?
A question mark
?
Left
Hemisphere
$
Right
Hemisphere
Draw (with your
left hand) what
you saw.
$
Visual - Composite words
Two words flashed simultaneously
LVF
RVF
KEY
CASE
P can say CASE and spell out the
word CASE with his right hand
P can pick up key from the grab bag
with left hand
BUT can not say KEY
OR join the words together
Touch – Objects in the
hands
Objects placed in right hand (LH) can be
named in speech and writing.
Objects placed in left hand (RH) –
participants will make wild guesses or
seem unaware that they are holding
anything at all.
Touch – Objects in the hands
continued
HOWEVER – if that same object is placed in a
grab bag with other objects, the participant
could find the original object with his left hand.
Participants cannot retrieve the object with their
right hand if it was first sensed with their left
hand.
Touch – Dual
processing
If two objects are placed simultaneously
one in each hand and then hidden two
separate grab bags, both hands can
select their own object but will ignore the
other hand’s objects.
Visual results summary
• If shown an object to the RFV, participants
can name and describe the object.
• If shown an object to the LVF, participants
cannot name the object but can draw it with
their left hand or pick it out of group of
objects.
• If shown an object to both visual fields and
given a pen in their left hand, they will name
what is in RVF but draw what is in the LFV.
Tactile results summary
• Objects placed in the right hand (left
hemisphere) could be named. Objects
placed into the left hand (right
hemisphere) could not be named but
could be drawn or picked up with their
left hand.
Conclusion
For split-brain patients
One half of the brain does not
know what the other half is doing!
Where is our evidence for
lateralisation of function?
Evidence for lateralisation of
function
LEFT HEMISPHERE
What is this hemisphere
specialised in?
Speech and writing.
What can this hemisphere
do?
Can communicate the visual
experiences of the right side
of the body and the right
visual field.
RIGHT HEMISPHERE
What can’t this hemisphere
do?
Is mute and cannot speak or
write.
What can this hemisphere
do?
Can show non-verbally that
mental processes centred
around the left side of the
body and the left visual field
have taken place.
An important question!
• Why don’t split-brain patients have
problems in daily life?
BECAUSE THEY SEE THINGS FOR
LONGER THAN 0.1 SECONDS.
• In everyday life the patients can overcome
their deconnection by …
 Moving their eyes
 Saying an answer out loud (heard by
both hemispheres).
Sperry (along with two others)
won the 1981 Nobel Prize in
Medicine for his work with
split-brain research
By the end of this session, you
will be able to;
• Describe the function of the corpus callosum.
• Identify the functions of the left and right
hemisphere.
• Describe the procedure and results of this
study.
• Be able to identify the actions of a ‘split brain’
patient when given different visual cues.
Summary quiz
1) What did all of the 11 patients suffer from
before surgery?
2) Which part of the brain was removed for split
brain patients?
3) Which hemisphere is language located in?
4) How long were the symbols/words flashed to
visual fields?
5) What was the Dependent Variable?
Summary quiz
6) Which visual field does an object need to be
presented to in a split brain patient in order that
they can name that object?
7) What happens if an object is presented to the
left visual field?
8) Which hemisphere cannot speak or write?
9) What does cross-wired mean?
10) How do the two hemispheres work in split
brain patients compared to ‘normal’ brains?
Key Terms
• Hemisphere (right
and left)
• Corpus callosum
• Visual field (right
and left).
• Epilepsy
• Lateralisation of
function
• Quasi-experiment
• Case study
•
•
•
•
Split brain surgery
Cross-wiring
Tactile task
Visual task
Finish with wordle (Choose
your own word to define and
link to the study)