Biological psychology- Sperry and Casey

Question 1

What is the corpus callosum

Answer 1

Connects the right and left hemisphere and carries most of the communication between the 2 halves

Question 2

What is laterilisation of function

Answer 2

The idea that the 2 hemispheres of the brain have different functions

Question 3

What does the left hemisphere control

Answer 3

Our command of language and our ability to communicate

Question 4

What does the right hemisphere control

Answer 4

In charge of spatial awareness and movement and object recognition

Question 5

What is contra lateral control

Answer 5

The idea that the brain is crosswired. The left hemisphere controls the right side of the body and all things processed in the left hemisphere display themselves on the right side of the body and vice versa

Question 6

What is hemispheric deconnection

Answer 6

This is for people with severe epilepsy. Its where the corpus callosum is cut so that communication between hemisphere is stopped reducing the “storms” in the brains for epileptic people

Question 7

Outline the background of Sperry (4)

Answer 7

Sperry wanted to investigate lateralisation of function, which is the belief that the two hemispheres have different functions, the right is in charge of special awareness tasks and the left in charge of language. Through contralateral control, which is the belief that our brains are cross wired so the left hemisphere is in charge of the right side of the body and vice versa, this proves our hemispheres are constantly communicating. Therefore, the only people that Sperry could test this on were people who had had their corpus callosum severed through the process of hemispheric deconnection in order to reduce severe symptoms of epilepsy. Sperry was interested in investigating the behavioural impact of a severed corpus callosum, and whether it would impact the behaviour or these individuals.

Question 8

What was the aim of Sperrys study

Answer 8

To record the psychological effects of hemispheric deconnection and to find evidence for laterilisation of function in “normal brains”

Question 9

What was the sample used in Sperrys study

Answer 9

11 people who had thes plit brain operation who had severe epilepsy previosuly at various times

Question 10

What is a tachistoscope

Answer 10

It projects visual stimuli onto a screen for a specified amount of time/ Images were projected to the left or right visual field
Images projected to RVF- processed by the LH
and vice versa

Question 11

What was the research method used in Sperrys study

Answer 11

A quasi experiment as it had a naturally occurring IV of whether people had split brain or not

Question 12

What was the dependant variable of Sperrys study

Answer 12

Their performance on visual or tactile tasks

Question 13

What was the procedure of Sperrys study

Answer 13

1) Each participant was studied alone
2) The participant had one eye covered and was asked to look at a fixed point in the centre of the screen on the Tachistoscope
3) Visual stimuli were then projected onto the screen either to the right visual field or the left visual field
4) The images were shown for 0.1 seconds each

Question 14

What were the 4 conditions they were placed in Sperrys study

Answer 14

One visual field
Both visual fields
Tactile one hand
Tactile both hands

Question 15

Describe the one visual field condition in Sperrys study

Answer 15

Each participant wwas shown a visual stimulus on the screen whilst focusing on the central fixation point
Shown one image in one visual field for 0.1 seconds. The had to name what they had seen

Question 16

What were the results for one visual field

Answer 16

When they were shown an image in their RVF it would be processed in the LH in charge of language and communication therefore the Ps would be able to say and draw what they had seen
However when shown an image in the LVF the image would be processed in the RH which is in charge of spatial awareness and movement so they wouldnt be able to say the word but could draw it

Question 17

Describe the both visual fields condition in sperry study

Answer 17

This time they were shown 2 different images one in each visual field at the same time

Question 18

What were the results in the both visual fields condition in Sperrys study

Answer 18

When asked to draw what they had seen they would draw the image from the LVF but if asked to say what they had seen they would say the image seen in the RVF

Question 19

Describe the tactile one hand condition in Sperrys study

Answer 19

Each participant was given an object in one hand. The participant was either asked to say or write down what was in their hand

Question 20

What were the results for Sperrys study in the tactile one hand condition

Answer 20

If the item had been placed in the participants right hand it could be identified in the left hemisphere and drawn with the right hand

Question 21

Describe the tactile both hands condition for Sperrys study

Answer 21

The participant works with their hands out of sight. They would be given 2 different objects one in each hand and then the objects are taken away. The participant is then asked to find the objects by touch from a pile of items or are asked to say what they have just held

Question 22

What were the results from Sperrys study in the tactile both hands condition

Answer 22

Participants were asked to find the objects by touch but only by the hand where the objects were first placed. If the hand touched the object that was not held then it would reject it almost as if the participant had never held the object before
This suggested that the 2 hemispheres are working separately so when they searched for the object they would only recognise if it was in the same hand

Question 23

What were the further results in Sperrys study

Answer 23

Sperry found that hemispheric deconnection did not appear to affect the participants intelligence or their personality. However the effects of the surgery seemed to have affected the patients in that they had short term memory deficits, fatigue and limited concentration spans

Question 24

What were the conclusions made by Sperry

Answer 24

Split brain patients appear to have 2 independent streams of consciousness each with its own memories, perceptions and impulses. This supports LAT

People with split brain have 2 separate visual inner world each with its own train of visual images

Split brain patients have a lack of cross integration where a second hemisphere does not know what the first hemisphere has been doing

Question 25

Identify one weakness related to the sample in this study (3)

Answer 25

One weakness of the sample is that it is very small and has low population validity, therefore is not representative of all people who have a split brain. Sperry could only gather 11 people to take part in his study on lateralisation of function, because not many people have had the split brain operation, therefore he could only apply the findings to these 11 people e.g. the fact that they could only say the visual stimulus that was presented to their right visual field. This is a weakness as it limits the usefulness of the research, as Sperry cannot generalise the findings of lateralisation of function to all people, not just those who have had the split brain operation due to severe epilepsy.

Question 26

Describe the dual processing task used in the research (2)

Answer 26

n the dual processing task, the participants put both of their hands through a wooden screen so they are out of sight and are given two different objects, one in each hand. They are given time to feel the objects and then put them back into a pile of other random items. The participants were then asked to find the objects by touch from the pile.

Question 27

Explain how split brain patients responded to visual material presented to their right visual field (2)

Answer 27

When a visual stimulus was presented to their right visual field, due to contralateral control, this would be processed in the left hemisphere which is in charge of language, therefore the participant could say what they had seen.

Question 28

Describe one way in which the study by Sperry lacked ecological validity (2)

Answer 28

Sperry’s study lacked ecological validity as the participants were only able to look at the visual stimulus for 0.1 of a second, which is very unrepresentative of real life as people can look at things for as long as they need in their everyday life, meaning the findings aren’t generalizable to real life

Question 29

Explain why it was appropriate for this study to lack ecological validity (2)

Answer 29

This was appropriate because if the participants had looked at the visual stimulus for longer than 0.1 seconds, then that would have given them time to manipulate their visual field and move their eye so that they could see the image in both visual fields, which would invalidate the dependent variable of the behavioural changes in their behaviour due to their split brain procedure.

Question 30

Outline one way in which the sample may be considered representative (2)

Answer 30

The sample was representative because it consisted of people who had all had the split brain operation due to severe epilepsy and the only people that this study can be generalised to are people who have a split brain as their hemispheres cannot communicate with one another, so the findings of this study can be generalised to them.

Question 31

Describe what Sperry found in relation to regions of the brain (4)

Answer 31

Sperry found evidence for lateralisation of function in the two hemispheres of the brain, right and left. He found that in this region of the brain, the right side is in charge of spatial awareness skills and the left is in charge of language. Also, through the process of contralateral control, the right side of the brain governs the left side of the body and vice versa and the two regions communicate with one another across the fibres of the corpus callosum. However, in people who have a severed corpus callosum, these hemispheres cannot communicate with one another, therefore, when visual restrictions are put upon these people, they cannot perform normal functions. This was found as when an image was presented to their left visual field for only 0.1 seconds, they couldn’t name this image as the right hemisphere is not in charge of language.

Question 32

Explain how the study links to the key theme of regions of the brain (4)

Answer 32

Sperry aimed to investigate lateralisation of function by measuring the behavioural differences of people with a severed corpus callosum. He used 11 men and women who had all has the hemispheric deconnection operation to relieve symptoms of epilepsy. They performed a serious of visual and tactile task e.g. an image was flashed to their right visual field for 0.1 seconds and they were asked if they could name it. They were also asked to try and find an item with their hands out of sight that had previously been in their hand for them to feel. It was found that when the participants were presented with an image in their left visual field, it would be processed in the right hemisphere therefore they couldn’t name it. This links to regions of the brain as Sperry clearly illustrated how the region of the brain, the corpus callosum, plays a major part in normal behaviour and if it is severed, there are behavioural changes.

Question 33

Explain how the study links to the biological approach (4)

Answer 33

The biological approach assumes that all behaviour has a physiological origin and a biological basis and is a result of our genetics which are inherited from our parents. (2) Sperry links to the approach as he illustrates how the behaviour of the 11 split brain participants was a direct result of the physiological origin of their severed corpus callosum, resulting in their hemispheres having no communication with one another. This led to findings such as, when an image was presented to the left visual field, they participants couldn’t name the image as their right hemisphere couldn’t communicate with the left which is in charge of language, outlining the biological basis of their behaviour. (2)

Question 34

What are the strengths of Sperrys research method

Answer 34

Highly controlled environment so allows for Sperry to reduce the risk of situational variables such as manipulating the visual field by showing each image for 0.1 seconds and asking them to focus on a fixation point. Increases internal validity

Question 35

What are the weaknesses of the research method used in Sperrys study

Answer 35

Study is a quasi experiment and the independant variable cannot be manipulated Sperry was unable to fully isolate the IV against individual different like one of the split brain patients may have more experience with such tasks and therefore would make them perform better. This will reduce internal validity

Question 36

What are the validity strengths in Sperrys study

Answer 36

High controls (same as research method)
Concurrent validity high as all of the results from the tactile or visual tasks agree with one another. For example when the image is processed in the right hemisphere it cannot be spoken and also when the item is being touched it is processed in the right hemisphere it cannot be said

Question 37

What are the validity weaknesses in Sperrys study

Answer 37

Low ecological validity- in real life the participants would be able to spend as long as they needed to look at images therefore they could manipulate their visual field and be able to say everything they see

Population validity also is low as the sample is quite limited- very small sample and only consists of people who have had severe epilepsy previously so cannot be generalised to all split brain people

Question 38

What are the reliability strengths in Sperrys study

Answer 38

Highly standardised procedure like Sperry maintaining that all participants complete the exact same visual and tactile tasks in the same way using the same scientific equipment like Tachistoscope so internal reliability increases

Question 39

What are the reliability weaknesses in Sperrys study

Answer 39

Low external reliability- quantitative data was not collected- data consisted of qualitative notes and observations on the participants behaviour on the visual and tactile tasks This means that comparisons will be difficult to make in order to check for the consistency of data

Question 40

How was Sperrys sample representative

Answer 40

Highly representative sample as all of the 11 participants had split brain operation so all had a severed corpus callosum meaning there hemispheres cannot communicate. This is the target population of Sperrys findings therefore the generilisability is relatively high

Question 41

What were the strengths regarding the type of data that Sperry used

Answer 41

Qualitative data was used as Sperry made notes on the participants behaviour when doing the visual and tactile tasks. For example how they responded to each of the images . This means that Sperry gained a lot of insight on their behaviour increasing our knowledge on laterlisation of function

Question 42

What were the weaknesses of Sperrys types of data

Answer 42

The use of qualitative data means that there was no objective quantitative measures gathered reducing the scientific nature of the study

Question 43

How is Sperrys study ethnocentric

Answer 43

Conducted in a western society so all of the findings were only applicable to western ideas of medicine and biological psychology
We dont know whether the split brain operation occurs in other cultures

Question 44

How does Sperrys study fit the nature debate

Answer 44

Sperry’s study highlights that biological factors such as the severed corpus callosum can impact behavior. For example he found that our left hemisphere within our brain allows us to process and use language which is an innate factor and the basis of our behavior

Question 45

How does Sperry fit the nurture debate

Answer 45

Participants could potentially learn to overcome the restrictions of the split brain operation in their everyday life by manipulating their visual fields. This increases the usefullness as practical applications can be developed to improve these peoples lives

Question 46

How does Sperry fit the determinism debate

Answer 46

Sperry highlights that 11 participants performance on the visual and tactile tasks could have been predetermined by the fact that they had had the split brain operation therefore the behavior was out of their control
Brain connections determine how we interact with the world meaning that we have little control over this

Question 47

How does Sperry fit the free will debate

Answer 47

However the split brain participants would have the chance to exercise their free will in their everyday life as they could manipulate their visual field and perform all normal functions. This reduces the stigma that may be associated with people with split brain like an employer not looking down on them as being incapable of performing normal functions

Question 48

How is Sperrys study scientific

Answer 48

One strength of the study by Sperry is that it uses highly scientific methods and follows principles of science such as the use of objective scientific equipment. For example when exploring the effects of hemispheric deconnection Sperry uses a Tachistoscope to control the amount of time each participant sees each image 0.1 seconds and objectively found that when participants see an image in their right visual field this will be processed in the left hemisphere so they can see it. This is a strength as it increases the usefulness of the study allowing Sperry to make objective scientific conclusions about LOF and the effects of split brain operation increasing knowledge of the brain regions

Question 49

How is Sperrys study not scientific

Answer 49

The quasi experimental method means that individual differences cannot be controlled for
Also the use of qualitative data means that some subjectivity may cause misinterpretation of findings

Question 50

How is Sperrys study considered to be socially sensitive

Answer 50

Causes stigma and controversy surrounding people with split brain operation highlighting that they have a different brain to other people and that they may be slower or unable to perform certain functions. This could cause embarrassment and marginalization from certain activities

Question 51

How is Sperrys study not socially sensitive

Answer 51

It can raise awareness of such behaviors and also of laterilisation of function increasing the usefulness of Sperrys findings and this study could be used to improve knowledge and help people with split brain

Question 52

How is Sperrys study ethical

Answer 52

Participants not exposed to a great deal of harm during the tasks and were informed of the reasons why they were completing the tasks. Also never deceived

Question 53

How is Sperrys study unethical

Answer 53

Ethical violations such as a slight exposure of embarrassment and psychological harm could create confusion as to why they cannot “say” what they had supposedly seen in their left visual field

Question 54

How is Sperrys study considered reductionist

Answer 54

Focuses on the biological basis of behavior which is the fact that a severed corpus callosum can cause psychological and behavioral issues ignoring environmental factors . This is a strength as Sperry could focus his attentions on cause and effect between having a split brain and behavioral differences increasing the scientific rigor

Question 55

How is Sperrys study holistic

Answer 55

It can be said to address situational variables as well as when the participants are not only in a controlled environment in which they can only see stimulus for a controlled period of time they will be able to manipulate their visual field and perform normal functions