Sperry

• Outline the background of Sperry’s research (4)

  1)Explain whatlateralisation of functionis.2)Describe the roles of the right and left hemisphere3)What Sperry aimed to doSperry was inspired by the idea oflateralisation of function.This was the idea thatthe two hemispheresof the brain in thecerebral cortex, theright and the left,have totally different functions.(1)The left hemisphere was believed to be in charge of language(1)and the right hemisphere in charge of spacial awareness and movement.(1)Sperry aimed to investigate these two functions further by using participants who had asevered corpus colosseumso that their hemispheres wereno longer communicating.(1)
• Corpus callosum


  The region of the brain that connects the left and right hemisphere, allowing them to communicate with one another.
• Tachistoscope


  The apparatus used in Sperry's study to allow the visual stimuli to be presented to the participants.
• What was the aim in Sperry's study?

  The aim of the study was to record the psychological effects of hemispheric deconnection and to find evidence for lateralisation of function in "normal brains ".
• What was the sample in Sperry's study? (3)

  - 11 people, both male and female

  -Had the split brain operation

  -previously suffered severe epilepsy
• What was the sampling method in Sperry's study?

  Opportunity sampling, as Sperry used patient who had already had the procedure done.
• What was the research method in Sperry study?

  Quasi experiment
• What was the independent variable in Sperry's study?

  Whether the participant had a split brain or not
• What was the dependent variable in Sperry's research?

  Performance on visual and tactile tasks
• Describe the one visual field task in Sperry's study (4)

  - Each participant was shown a visual stimulus on the screen whilst focusing on the central fixation point.

  -they were shown one image in one visual field.

  - They were shown the image for 0.1 seconds.

  - After, they were asked to name/say what they had seen.
• What was the result of one visual field task in Sperry's study ? (2)

  - When participants were shown in image in there (RVF) this image would be processed in the left hemisphere which is in charge of language therefore the participant would be able to say and write what they had seen.

  - When participants were shown an image in their (LVF) this image would be processed in the right hemisphere which is in charge of spatial awareness therefore they wouldn't be able to say the word, but they could draw it.
• Describe the both visual fields task in Sperry's study

  This time they were showing two different images one in each visual field at the same time.
• What was the result of the task: both visual fields in Sperry's study?

  When participants were 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.

  
  

  For example:

  If participants were shown $ sign to the left visual field and a @ to the right visual field they would be able to draw the $ and say the @
• Describe the task: tactile one hand in Sperry's study (2)

  - each participant was given an object in one hand.

  - The participants were either asked to say or write down what was in their hand.
• What was the result of the task: Tactile one hand in Sperry's study?

  If the item had been placed in the participants right-hand it could be identified in speech and writing with the right hand.
• Describe the task: tactile both hands/dual processing task in Sperry' study

  The participant works with their hands out of sight. They will be given to different objects, one in each hand and then the objects are taken away. The participant is an asked to find the objects by touch from a pile of items or asked to say what they had just held.
• What was the result of the task: tactile both hands/dual processing task and what does this suggest in Sperry's study?


  Participants were able to find the object by touch but only by the hand where the object was the first place. If they haven't touched The object that was not held then it would reject it, almost as if the participant had never held the object before.

  
  

  This suggests that the two hemispheres are working independently so when they searched for the object they would only recognise if it was in the same hand.
• What were other results found about the patients with hemisphere deconnection in Sperry's study?

  Through the case studies, Sperry found that the hemisphere deconnection did not appear to affect the participants' intelligence or their personality. However, the effects of the surgery did seem to have affected the patients in that they had short-term memory deficits, fatigue more quickly in reading and have limited concentration spans and orientation problems (coordinating body etc).
• Conclusions of Sperry's study (3)

  1.Split brain patientsappear to havetwo independent streams of consciousness, each with itsown memories, perceptions and impulses: effectively,two minds in one body. Thissupports the argument of lateralisation of function. This is, that different areas and hemispheres of the brainspecialise on different tasks, such as the left side being responsible for language.

  2.People withsplit brainshavetwo separate visual inner worldseach with its own train of visual images.

  3.Split brain patientshave alack of cross integrationwhere asecond hemisphere does not know what the first hemisphere has been doing.
• Strength of the research method in Sperry's study

  Highly controlled environment allows for Sperry to reduce the risk of situational extraneous variables such as; manipulating their visual field by only showing each image for 0.1 seconds and asking them to focus on the fixation point. This increases theinternal validity and scientific nature of the study.
• Weakness of the research method in Sperry's study

  Due to the fact that the study is a quasi-experiment and the independent variable cannot be manipulated, Sperry was unable to fully isolate the IV against individual differences e.g. one of the split-brain patients may have more experience with such tasks and therefore this makes them perform better.Reduces the internal validity to some extent.
• How does Sperry's study have low Ecological validity?


  Ecological validity is low as 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.
• How does Sperry's study have low Population validity?

  Population validity low as the sample is very small and only consists of people who have previously had severe epilepsy so cannot be generalised to all split brain people
• How does Sperry's study have high Concurrent validity?

  Concurrent validity is also high as all of the results from the tactile and visual tasks agree with one another e.g. when the image is processed in the right hemisphere, it cannot be spoken and also when the item being touched is processed in the right hemisphere, it cannot be said.
• How does Sperry's study have high Internal reliability?

  Highly standardised procedure e.g. sperry maintains that all participants complete the exact same visual and tactile tasks in the same way using the same scientific equipment e.g. Tachistoscope. This increases ininternal reliability.
• How does Sperry's study have low external reliability?

  Low external reliability as quantitative data is not used. The data consists of qualitative notes and observations about 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.
• Strength of Sperry's study sample

  Highly representativesample as all of the 11 participants have had the split brain operation and therefore have a severed corpus calosum meaning their hemispheres cannot communicate. This is the target population of sperrys findings therefore, generalisability is relatively high.
• Weakness of Sperry's study sample

  However, the sample is very small and consists of people who have all had severe epilepsy previously, therefore, only generalised to those 11 people and not the wider target population.
• Strength of qualitative data being collected in Sperry's study

  Qualitative data was gathered as sperry made notes on the participants behaviour when doing the visual and tactile tasks e.g. how they responded to each of the images. This means that sperry gained a lot of insight on their behaviour, increasing our knowledge of lateralisation of function.
• Weakness of qualitative data being collected in Sperry's study

  However, the use of qualitative data means that there was no objective quantitative measures gathered, reducing the scientific nature of the study.
• How is Sperry's study ethnocentric?

  The study was conducted in a western society meaning that all of the findings are only applicable to Western ideas of medicine and biological psychology. We do not know whether the split brain operation occurs in other cultures.
• How does Sperry's study illustrate the nature debate?

  Sperry's study highlights that biological factors such as a severed corpus callosum can impact behaviour. For example, he found that our left hemisphere within our brain allows us to process and use language, which is an innate factor and basis of our behaviour.
• How does Sperry's study illustrate the nurture debate?

  However, the participants could learn to overcome the restrictions of the split brain operation in everyday life, by manipulating their visual fields. Increases the usefulness as practical applications can be developed to improve these people's lives.
• How is Sperry's study scientific?

  This is a highly scientific study as it uses many principles of science e.g.

  High controls (cause and effect)

  Standardisation (replicability)

  Scientific equipment

  Deduction (finding evidence for lateralisation of function)
• How is Sperry's study not scientific?

  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.
• What is a strength of Sperry's study being socially sensitive?

  Such socially sensitive research can also raise awareness of such behaviours and also of lateralisation of function, increasing the usefulness of sperrys findings and this study can be used to improve knowledge and help people with a split brain.
• What is a weakness of Sperry's study being socially sensitive?

  The study could be seen to be socially sensitive as it causes a stigma and controversy surrounding a split brain person, highlighting that they do have a different brain to other people and that they may be slower or unable to perform certain functions. This could cause embarrassment or marginalisation from certain activities.