Studies of Cognitive Processes
Roger Sperry and Michael Gazzaniga have conducted research into the effects of the ‘split-brain’. A
split-brain occurs when the corpus callosum is severed. The corpus callosum allows the cerebral
hemispheres to interact and communicate. When this is taken away, the two hemispheres act
independently and can no longer communicate to perform actions.
Sperry and Gazzaniga were able to identify the specialist functions of each hemisphere.
Some of their findings include:
 Words presented to the right visual field are processed in the left hemisphere; patients
could read and report words verbally. The left hemisphere can identify words and name
them.

Words presented to the left visual field are processed in the right hemisphere; patients are
unable to report words verbally, could select item by touch behind screen but were unable
to say why selected. Right hemisphere can identify words but not name them.

When presented with different words on each side of the screen at the same time, patients
were able to read and report verbally the word presented to the right visual field. Left
hemisphere can identify words and name them.

When presented with different words on each side of the screen at the same time, patients
were unable to verbally report words in the left visual field. Right hemisphere can process
words but cannot name them.

When presented with a picture of an object to the right visual field or left visual field and
asked to verbally identify the object or reach under the screen and select the object by
touch, when the picture is flashed to left visual field patients were unable to verbally name
the object but could pick it up with their left hand. Right hemisphere can identify pictures by
touch but cannot name them.

When presented with a picture of an object to the right visual field or left visual field and
asked to verbally identify the object or reach under the screen and select the object by
touch, when the picture is flashed to the right visual field (processed by left hemisphere),
the patient could easily name it verbally. Left hemisphere can identify pictures and name
them.
Split-brain – student activity
Youtube – Mike Gazzaniga and Alan Alda
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Perceptual anomalies
An irregularity in perception. A mismatch or inconsistency between the perceptual experience and
physical reality.
Motion after-effect
A perceptual illusion of movement of a physically stationary visual stimulus following exposure to
visual motion.
When we view a moving object and then a static (not moving) object. The static object appears to
move, in the opposite direction to the original moving object.
Change blindness
The difficulty observers have in noticing a large change in a visual scene.
Change blindness occurs when change is expected and when change is unexpected. When it is
expected it can still take a long time to find the change.
Change blindness occurs when there is a visual disruption. The ‘flicker’ technique is when a visual
scene is flashed on screen to a viewer. The scene is then swapped for another identical image.
However the second image has one change to it.
Inattentional blindness: a failure to notice something in a scene when the same scene continually
remains in sight and there is no reliance on memory.
Inattentional blindness is different from change blindness, as there is no visual disruption. A viewer’s
attention is drawn to a particular part of the scene and then fails to notice other stimuli within that
scene.
Youtube - Mind’s eye – part 3 of 4 (experiment with two men) [change blindness]
Youtube – The door study [change blindness]
Youtube – test your awareness [inattentional blindess]
Youtube – who dunnit? [inattentional blindness]
Synaesthesia
A perceptual experience in which stimulation of one sense produces additional unusual experiences
in another sense.
For example: seeing colour with sounds (piano), seeing letters in colour, smell by touching a shape,
taste from hearing words.
Most common – seeing letters in colour (grapheme-colour synaesthesia)
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Brain Research Methods
Direct Brain Stimulation: two methods – ESB and TMS
Electrical Brain Stimulation (ESB):involves the surgical opening of the skull and delivering a
measured electrical current (via an electrode) to a specific brain area or structure. The effect on a
patient’s behaviour is observed. Highly invasive as it requires surgery.
Transcranial Magnetic Stimulation (TMS): involves using magnetic pulses to stimulate nerve cells in
the brain and observing the resulting behaviour. It is considered non-invasive.
Brain Imaging Techniques: CT, MRI, fMRI, PET, SPECT
Computed Tomography (CT): takes x-rays of the brain at different angles to produce a computerenhanced image of a cross-section of the brain. It provides information about brain structures.
Magnetic Resonance Imaging (MRI): uses a magnetic field and radio waves to vibrate brain neurons
and produce a detailed, still, computer-enhanced 3D image of brain areas and structures. More
detailed than CT. Shows brain structure.
Functional Magnetic Resonance Imaging (fMRI): detects changes in oxygen levels in the blood
flowing throught the brain and combines this data into a detailed, computer-enhanced 3D
representation of the active brain. Shows structure and function of the brain.
Positron Emission Tomography (PET): involves the injection of radioactive glucose into the
bloodstream, tracking the blood flow to the brain and combining this data into a series of computer
generated colour coded images of the level of activity in various brain areas while engaged in
different tasks. Show brain function.
Single Photon Emission Computed Tomography (SPECT): involves the injection of a radioactive
tracer substance into the bloodstream and results in 3D images of internal brain structure and
functioning. Show brain function.
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Brain Imaging Techniques
Imaging Technique
Electrical stimulation of the
brain (ESB)
How it works
Involves using an electrode to deliver a
precisely regulated electric current to the brain,
thereby stimulating a specific area of the brain.
What it is useful for
Finding which parts of brain control which parts of
body.
Limitations
The brain functions as a whole in an integrated
way and that most of the brain is active when we
are doing almost any task.
It is an extremely invasive research procedure
Transcranial Magnetic
Stimulation (TMS)
A magnetic pulse is delivered through the skull
and temporarily activates or disrupts the
normal activity of neurons in specific brain
areas.
Computerised axial
tomography (CAT) Scan
A computer enhanced X-ray of a slice (crosssection) of the brain created from X-rays taken
from different angles.
Magnetic resonance imaging
(MRI)
However, the more advanced brain imaging
technique called magnetic resonance imaging
(MRI) provides moving images and more detail
about specific structures that does the CAT
scan.
MRI uses a similar technique to the CAT scan,
but instead of using an X-ray, harmless radio
frequencies are used to vibrate atoms in the
neurons of the brain (or other cells in the body).
The amount of vibration is detected and
analysed by a computer which then creates a
clear image of the brain or other parts of the
body being scanned.
If electrical stimulation of a specific brain area
initiates a behavioural response, then that specific
area of the brain controls or is involved in that
response.
It can be used to assist brain mapping without the
invasive surgical procedure.
TMS has also been used as a therapy for
depression.
As with case studies, involves difficulties in
generalising the results.
CT is extremely useful for identifying the precise
location and extent of damage to or abnormalities
in various brain structures or areas. A CT scan can
reveal the effects of strokes, tumors, injuries and
other brain disorders
Like CT, MRI has primarily been used for
diagnosing structural abnormalities of the brain.
However, MRI can be used to detect and display
extremely small changes in the brain. For example,
MRI can more clearly distinguish between brain
cells that are cancerous and those that are
noncancerous.
Shows only brain structure or anatomy. It does not
provide information about the activity of the brain;
that is, brain function.
The long term effects of TMS have not yet been
established.
TMS does not show the structure of the brain or
where brain function is occurring.
One of MRI’s limitations that it cannot be used
with people who have internal metallic devices
such as heart pacemakers or steel pins in bones.
However its main limitation is that it shows only
brain structure, or anatomy—not function.
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Functional magnetic
resonance imaging (fMRI)
The technique is based on the standard MRI,
and measures subtle changes in blood–oxygen
levels in the functioning brain. When an area of
the brain is active, there is increased blood flow
to that area, as more oxygen is required by the
active, functioning neurons.
A computer analyses the blood–oxygen levels in
the area, and creates an image with colour
variations.
Used to record the levels of activity in different
areas of the brain while the participant (or patient)
is involved in a cognitive activity of some kind,
such as thinking, imagining, remembering or
talking.
When using fMRI, as is the case with PET, the
researcher needs to remain aware of the fact that
observed differences in levels of brain activity of
different areas may not just be the direct result of
the specific task being undertaken.
One application of fMRI in brain research has been
in the study of hemispheric specialization with
intact brains.
The levels of brain activity may also be associated
with other factors relating to the research task
performed by the participant; for example, task
duration (that is, the length of time taken to do the
task) and task difficulty.
fMRI are more detailed than PET images.
Positron Emission
Tomography (PET)
Provides information about the functioning of
various parts of the brain. Prior to the scan
being taken, the person is given a sugar-like
substance that contains a harmless radioactive
element. When this substance enters the
bloodstream it travels to the brain. As
particular parts of the brain are activated, the
substance emits radiation which is detected the
PET scanner.
Used to record the levels of activity in different
areas of the brain while the participant (or patient)
is involved in a cognitive activity of some kind,
such as thinking, imagining, remembering or
talking.
PET was originally designed to diagnose
abnormalities in the brain and is highly effective if
that area of the brain is structurally intact).
PET technology can also provide information on
the brain functioning of specific groups or
populations of research interest, such as people
with mental illnesses.
Single Photon Emission
Computed Tomography
(SPECT)
Similar to PET, however, a longer-lasting
radioactive tracer is used to record functioning
of the brain.
Useful for pinpointing active areas of the brain.
PET requires injection of a radioactive substance,
but the radiation dosage is harmless, and risks to
the person’s health areconsidered to be negligible.
However, the need for radiation means that a PET
session must be kept short so that the person does
not receive too much radiation.
Furthermore, PET needs a 40-second interval
between scans, and each individual scan takes 30
seconds to complete. This means that PET doesn’t
necessarily pick up the very rapid progression, or
changes in brain activity associated with different
brain functions.
SPECT scans are not as clear and finely detailed as
PET scans.
Less expensive than PET.
Longer-lasting radioactive tracer means extended
activities can be undertaken and brain function
recorded.
SPECT only shows the function of the brain, not the
structure.
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The Peripheral Nervous System
The Peripheral Nervous System comprises all those nerves that carry information between the rest of
the body and the central nervous system. These nerves may be composed of sensory neurons
carrying sensory information to the brain in ascending tracts or motor neurons carrying messages
about movement from the brain to the body via descending tracts.
The Peripheral Nervous System is composed of the Autonomic Nervous System and the Somatic
Nervous System.
Somatic Nervous System: transmits sensory information received from sensory receptor cells
inwards towards the CNS, and motor messages from the CNS to the body’s voluntary skeletal
muscles.
The Autonomic Nervous System (ANS) is important in aiding survival through its two divisions: the
sympathetic division prepares us physically for action in an emergency; the parasympathetic division
calms the body and restores homeostasis.
Autonomic Nervous System: transmits motor messages from the brain to the body’s internal organs
and glands, which results in involuntary activity of internal organs and glands, and transmits
messages back to the brain about the activity level of these organs and glands.
Sympathetic Nervous System: the branch of the ANS that alters the activity level of internal muscles,
organs and glands to physically prepare our body for increased activity during times of high
emotional or physical arousal.
Parasympathetic Nervous System: the branch of the ANS that maintains an energy level appropriate
for normal bodily functioning caused by the domination of the sympathetic nervous system.
Sympathetic = arousal, fight/flight response
Parasympathetic = calming, homeostasis
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