Paper 2 - Sperry on Split Brains

Question 1

What is the background of this study ?

Answer 1

The brain has two hemispheres that are connected by the corpus callosum. People with epilepsy have seizures, some people had their corpus callosum severed to stop seizures.

Question 2

What’s the aim of this study ?

Answer 2

To show the independent streams of consciousness and memory possessed by each hemisphere.

Question 3

What type of study is this ?

Answer 3

• Quasi experiment: The IV is not directly manipulated, the change is naturally occurring.
• Snapshot study: done in one moment of time.

Question 4

What’s the IV ?

Answer 4

Split brain procedure.

Question 5

What’s the DV ?

Answer 5

Performance on verbal and tactile tasks.

Question 6

Describe the sample.

Answer 6

• opportunity sampling obtained a sample of 11 patient who had the split brain procedure.
• One had it 5.5 years ago, another 4 years ago, others had it between these times.

Question 7

What are the materials in this study ?

Answer 7

• Tachistoscope: Device that displayed images for a specific amount of time.
• Visual stimuli that are projected at a high speed.
• Physical objects for the pps to touch.

Question 8

Describe the procedure.

Answer 8

Visual stimuli are presented onto the tachistoscope for 0.1 second.
2. Verbal task: A composite word like ‘keycase’ is shown on the screen, ‘key, to the LVF and ‘case’ to the RVF. pps have to report back the word they saw.
2. verbal task: an image id shown to the LVF or the RVF and the pps have to report what they saw.
3. Recognition: Image is shown to the LVF or RVF and the pps are asked to indicate recognition.
4. Tactile task: Image is shown to LVF or RVF and they have to identify the object with one of their hands.
5.Dual processing task: Two objects are placed simultaneously, one in each hand, then into a pile of objects. the pps has to recognise the object in the pile.

Question 9

What are the base line results ?

Answer 9

• If a picture is shown in one visual field, it is only recognised by that visual field.
• If visual material appears in the RFV the pops would describe it by speech, if it was shown to the LVF they would describe it by drawing. If the same visual material is projected onto the LVF they would say they didn’t see anything.
• If you ask him to use his left hand to point to the object he just saw, he points to the object he couldn’t see.

Question 10

What are the results from the $ and ? signs ?

Answer 10

If a $ sign is shown to the LVF and a ? to the RVF, the ops will draw the $ but say they saw a ?

Question 11

What are the results from composite words task ?

Answer 11

When keycase, key to the LVF and case to the RVF, pps would select a key from objects with his left hand but spell the word case with his right hand and say case allowed when asked what he saw.

Question 12

What are the results from participants using their left hand ?

Answer 12

If an object is held in the left hand the pps say ‘the hand is numb ‘ or ‘i don’t get messages from that hand’. However if placed with other objects the pps can identify the same object with their left hand.

Question 13

What are the effects on everyday life for patients with split brain procedure ?

Answer 13

• Split brain patients tend to be unaware of the separate visual input, in life problems can be solved by moving the eyes or saying something out loud to share the information across the two hemispheres.
• Some personalities and IQs change
• Some struggle with short term memory and had limited attention spans.

Question 14

What are the conclusions from this study ?

Answer 14

• Patients have two independent streams of consciousness, memory, impulses and perception.
• The right hemisphere has no language control but controls localisation of stimuli.
• The left hemisphere controls language.
• Split brain patients have a lack of cross- integration, meaning each hemisphere is unaware of what the other hemisphere is aware off.

Question 15

Evaluate the research methods

Answer 15

• strengths: the use of objective tests to measure the patients capabilities - unbiased means of seeing the effects of the operation. laboratory environment means the pps can be closely watched.
• weaknesses: a quasi experiment lacks control of the iv and extraneous variables,e.g. all the pps had epilepsy, this may have effected their behaviour not the surgery. There’s a possibility that the two hemispheres weren’t fully split leaving some communication. Lacks ecological validity due to the lab environment.

Question 16

Evaluate the sample

Answer 16

• strengths: pps offered an opportunity to study an aspect of the way the brain works that couldn’t be done on typical brains.
• weaknesses: capabilities of pps may have been effected by epilepsy before the operation, also the operations were done at different times so some may have learnt to deal with it more and some may be traumatised still - cannot be generalised to the wider population.
• The small sample makes it difficult to study individual differences,e.g. some people have that one hemisphere controls that side of the body or language is in the right hemisphere.

Question 17

Evaluate the type of data collected

Answer 17

• strengths: Primary data was collected specifically for the aim of the study - it can show the way two halves of the brain perform.
• Qualitative data allowed for rich detail about the effects of split brain procedure.
• Weaknesses: the sample size and qualitative data means its not possible to apply statistics to the data and workout the quantitative differences between split brains and typical brains.

Question 18

Evaluate the reliability

Answer 18

• The tasks were standardised and the procedure was carried out in the same way for each pps and the results could be interpreted in the same way.
• The consistent results backed up the consistency of the procedure.
• However, individual differences means that the study is not completely replicable

Question 19

Evaluate the ethnocentrism

Answer 19

The study reflects a western concern with measuring behaviour and identifying areas in the brain that control the behaviour as an explanation. This is a western method if dealing with patients epileptic seizures.

Question 20

Evaluate the validity

Answer 20

• The internal validity is effected by the differences in time since the patients had their operation, and the possibility that the two hemispheres weren’t fully served, or that before the operation, the epilepsy changed the patients behaviour, not the operation - extraneous variables.
• Low ecological validity and low population validity due to the sampling bias.

Question 21

Evaluate the ethics

Answer 21

• Ultimately the study is considered as ethic as the operations weren’t done for the study and it was a breakthrough in out knowledge of the brain.
• Fully informed consent may not be given as patients may have problems not understanding the study as they may still be traumatised from the split brain operation.
• Repeated testing may be stressful for the pps causing them to become embarrassed, this may cause psychological harm. It may have been he first time that the patients realised the effects of the operation, causing stress and confusion

Question 22

How is this study related to the determinism/free will debate ?

Answer 22

It stands with the determinism side as it assumes that the brain connections determine our performance on verbal and tactile tasks in the world.

Question 23

How is this study related to the nature/nurture debate ?

Answer 23

• Nurture: Patients learnt methods of explanations to deal with their split brain for example looking around or saying the name of something out loud, they also stated that their hand was numb, or guessed what the object was.
• Nature; The brain itself and the connections between the two hemispheres is a biological reason for behaviour.

Question 24

Where does this study stand with psychology as a science ?

Answer 24

• It is a science
• Controlled, standardised methods allows for replicability.
• Objects and apparatus were specific and accurate.

Question 25

How does this study relate to new understandings ?

Answer 25

• Sperry was awarded a Nobel prize for his work as it advanced out knowledge of the brain and the two hemispheres
• Many films and books were inspired from his work.

Question 26

How is this study a reductionist view ?

Answer 26

• The ability to perform verbal and tactile tasks is down to brain connections between the two hemispheres.
• Doesn’t consider the effects that epilepsy had on the pps before the procedure