Sperry's Study

Question 1

What does the background of Sperry’s study involve?

Answer 1

Epileptic patients who had undergone split brain surgery to allow the understanding of what each of the hemispheres does.

Question 2

What does epilepsy involve?

Answer 2

ITs a medical condition brought on by abnormal electrical impulses discharging within the brain and disrupting normal brain function

Question 3

What is the corpus callosum?

Answer 3

The two sides of the brain are linked together by nerves called commissural fibres, which are bundled together into structures called commisures. The largest of these “bundles” is called the corpus callosum.

Question 4

What is a commissurotomy?

Answer 4

Its a split brain operation where the corpus callosum is severed to separate the two hemispheres and limit life threatening seizures which are caused by distributed electrical impulses.

Question 5

What does the left hemisphere of the brain control?

Answer 5

LANGUAGE
Writing
Reading
Listening
Calculation
Logic
Analysis

Question 6

What does the right hemisphere of the brain control?

Answer 6

EMOTION + VISUAL PROCESSING
Idea
Image
Colour
Art/Music
Daydreaming

Question 7

What does the term ‘CONTRALATERAL CONTROL’ mean?

Answer 7

Each hemisphere in our brain controls the OPPOSITE side of our body.

Question 8

What does the term ‘Lateralisation of Function’ mean?

Answer 8

One side of the brain has a different role from the other

Question 9

What was Sperry’s research aim?

Answer 9

To study the effects of brain hemisphere disconnection and show that each hemisphere has different functions. In other words to map, lateralisation of brain function, and show that information in one side of the brain is not accessible to the other side.and the functions of the separated hemispheres

Question 10

What type of experiment did Sperry conduct?

Answer 10

Quasi Experiment

Question 11

Why did Sperry conduct a Quasi experiment?

Answer 11

The independent variable was if the participants had had the surgical procedure (commissurotomy) and it is naturally occurring/is unethical to manipulate

Question 12

What Sample did Sperry use?

Answer 12

11 split-brain participants who already had a commissurotomy prior to the study
- The subjects had all suffered from severe epilepsy and had not responded to drug therapy

Question 13

What sampling technique did Sperry utilise?

Answer 13

Opportunity

Question 14

What is an advantage of this sample?

Answer 14

It is species specific behaviour and it would be easy to generalise findings to others as peoples brains are all structured in the same way

Question 15

What controls did Sperry have in his study?

Answer 15

SAME IMAGES (flashed for 1/10th of a second)

SAME EQUIPMENT

SAME ORDER OF PRESENTATION OF IMAGES/OBJECTS

Question 16

What is a disadvantage of this sample?

Answer 16

The sample size of 11 is very small
Epileptic brain participants - different from normal group - so limited generalisability (low population validity

Question 17

What equiptment did Sperry use in the study?

Answer 17

a TACHISTOSCOPE

Question 18

What was the procedure for the visual investigations?

Answer 18

Participants were asked to fix their eyes on a fixation point in the middle of the screen.
Their hands would be under the screen and out of sight. The stimuli would be projected images to one side of screen for only 1/10th second to allow info to only enter one visual field.

Question 19

When an object is presented to the RIGHT visual field which hemisphere does the information go to?

Answer 19

Left Hemisphere

Question 20

When an object is presented to the RIGHT visual field (which goes to the LEFT hemisphere) what can participants do?

Answer 20

Describe what they saw in a spoken or written format

Question 21

When an object is presented to the LEFT visual field which hemisphere does the information go to?

Answer 21

Right hemisphere

Question 22

When an object is presented to the LEFT visual field (which goes to the RIGHT hemisphere) what can participants do?

Answer 22

Ps insist that they’ve not seen anything but if asked to point to a matching object on the table with their LEFT hand they can do so.

Question 23

Different visual stimuli were presented simultaneously to different visual fields (e.g. an image of an apple to the left; an image of a key to the right), and the participant was asked to draw with his left hand (out of sight) what he had seen

Answer 23

Able to say they had seen a key (RVF)- but unaware of anything else.
Able to draw apple (LVF) but not consciously know why. Able to name object once they had seen the drawing in the RVF.

Question 24

When a Simple mathematical problems were presented to the left visual field what happened?

Answer 24

Were able to sort objects by shape, size, texture- using their left hand.

Question 25

What happened when A nude pin-up was presented to the left visual field?

Answer 25

Participants would giggle/look embarrassed when nude picture appeared but couldn’t say what they saw or why they were giggling.

Question 26

Why does the research get these results?

Answer 26

Info being presented to the left visual field was being sent to the right hemisphere which does NOT control language therefore the P is not able to put into words what has been presented to them

Question 27

During the tactile tests what happened when objects were felt by the right hand only?

Answer 27

Ps described object BY NAME in speech and writing

Question 28

During the tactile tests what happened when objects were felt by the left hand only?

Answer 28

They could find it with their left hand - by touch – in a bag full of objects.
When the objects were placed in one hand, they could point to what the object was-with the same hand which had held the object.

Couldn’t use speech to describe object - made wild guesses-seemed unaware of object in their hand – as they had no conscious awareness of it.

Question 29

What were the conclusions about the left hemisphere?

Answer 29

Left hemisphere- specialised for speech and writing, and for language organisation
Can communicate anything from the right visual field, or experiences of the right side of the body

Question 30

What were the conclusions about the right hemisphere?

Answer 30

Right hemisphere-can’t speak/write
- Can show NON-VERBALLY ( subconscious ) that mental processes from left visual field and left side of body are present

Question 31

Whats a useful application of Sperry’s conclusions?

Answer 31

Medical profession who can help patients with similar disorders

Question 32

Evaluate the ethics of Sherry’s study?

Answer 32

Ethics- the study was conducted ethically as the participants consented to be in the study, participants were not lied to in any way so deception was not used and they were not harmed in any way or stressed by the experimental tests.

No ethical guidelines were broken!

Question 33

How could Sherry’s study be criticised for being ethnocentric?

Answer 33

The tests were not administered to a variety of cultures so it could be argued that the study was culturally bias.
People from other countries might have a difficult time fully understanding the test e.g. with other languages (e.g. Chinese – with symbols) may find it harder to do tests

Question 34

How is Sperry’s study not ethnocentric?

Answer 34

It could be argued that Sperry’s study is not very ethnocentric as it focuses on brain lateralisation and anatomy.
The study was investigating species-specific behaviour
(all human brain structure the same) so therefore the tests cannot have been bias to a particular culture as physically, we’re all alike.

Question 35

Evaluate the reliability of Sperry’s study?

Answer 35

Internal reliability;
The tasks were carried out in laboratory conditions using specialised equipment so it was highly standardized and easily replicable
The study included epileptic patients whose brain chemistry is different.. Perception of images, objects in study very different

External Reliability
A small, specific sample was used 11 people – so meaning that the findings may not be representative of other people because there may have been individual differences – i.e. Medical differences in brain structure influencing the results. So this study lacks external reliability.

Question 36

Evaluate the internal validity of the findings?

Answer 36

High internal validity as his findings showed lateralisation of function as their halves of their brains couldn’t work together. The procedure did measure lateralization of function as he used a tachistoscope to isolate each side of the participants brain.
Low validity- other factors which may have affected behaviour Participants went through brain surgery which can affect their brain

Question 37

Evaluate the population validity of Sperry’s study?

Answer 37

Not generalisable- small sample size (11 people)
Participants had experienced different levels of commissurotomy
Doesn’t represent people with epilepsy that haven’t had commissurotomy

Question 38

Evaluate the ecological validity of Sperry’s study?

Answer 38

Tactile - High - Likely to happen in real life, for example putting hand in bag trying to get something without seeing it
Visual - Low - The findings would be unlikely to be reproduced in a real life situation as stimuli are not selectively delivered to one hemisphere. This does represent everyday life of “split-half” patients

Question 39

How does Sperry’s study link to the debate of psychology as a science?

Answer 39

The study was carried out in a controlled laboratory experiment, (objective) which fulfil the scientific criteria of theory, control, evidence and replications. This supports the claim that psychology is a scientific discipline.
It is possible to prove what Sperry is saying about the abilities of split-brain patients by replicating the study, in theory his work is falsifiable.

Question 40

How does Sperry’s study link to the debate of usefulness?

Answer 40

Sperry’s work was groundbreaking in beginning to understand the physiology of the brain; that is, how the brain works. This showed the importance of the corpus callosum as it’s the pathway for the communications of the two sides.

Question 41

How does Sperry’s study link to the debate of freewill/determinism?

Answer 41

Sperry suggests that the participants behaviour was biological determined as undergoing a commissurotomy. This means that split-brain patients are no longer able to name objects that they touch with their left hand out of sight. Their inability to do this is determined by psychological factors.