Lateralisation and split brain research

Question 1

What did Sperry want to find out? (1968)

Answer 1

If hemispheric lateralisation was the same for other functions in the brain

Question 2

What RPS did Sperry use for his split brain research?

Answer 2

Individuals who had undergone the same surgical procedure - commissurotomy
The corpus callosum and other tissues that connect the two hemispheres were cut in order to control seizures

Question 3

What was prevented in split brain patients?

Answer 3

Communication between the two hemispheres

Question 4

What did the use of split brain patients allow Sperry to see?

Answer 4

To which extent the two hemispheres were specialised and whether tasks are performed independently of each other

Question 5

What is hemispheric lateralisation?

Answer 5

The idea that the two halves of the brain are functionally different and that each hemisphere has functional specialisations

Question 6

What does the right hemisphere control?

Answer 6

Visual motor tasks

Question 7

What does the left hemisphere control?

Answer 7

language

Question 8

What is the role of the corpus callosum?

Answer 8

Connects the two hemispheres, allowing communication between the two

Question 9

What were three of the experiments which Sperry carried out?

Answer 9

• Describe what you see
• Tactile test
• Drawing task

Question 10

What was the procedure for describe what you see?

Answer 10

A picture was presented to either the left or the right hemisphere and they had to describe what they saw

Question 11

What happens when the picture is presented to the right visual field?

Answer 11

The patient could describe what they had seen, demonstrating the superiority of the left hemisphere when it comes to language production.

Question 12

What hemisphere processes the right visual field?

Answer 12

Left hemisphere (language)

Question 13

What hemisphere processes the left visual field?

Answer 13

Right hemisphere (motor)

Question 14

What happens when the picture is presented to the left visual field?

Answer 14

The patient could not describe what they had seen, saying that there was nothing present often

Question 15

What was the procedure of the tactile test?

Answer 15

an object was placed in either the right or left hand and they had to either describe what they felt or select a similar object from a series of other objects in front

Question 16

In the tactile test, what happened when the object was placed in the left hand? (processed by right hemisphere)

Answer 16

• The patient couldn’t describe what they had felt and could only make wild guesses
• The left hand could identify an object by selecting a similar appropriate object

Question 17

In the tactile test, what happened when the object was placed in the right hand? (processed by left hemisphere)

Answer 17

• The patient could describe what they had felt verbally

- The patient could also identify an object presented in the right hand by selecting similar objects

Question 18

What was the procedure of the drawing task?

Answer 18

The patients were presented with a picture or words in front of them in either the left or right visual field and they had to draw what they had seen

Question 19

What were the findings for the left hand in the drawing task? (controlled by the right hemisphere)

Answer 19

the drawings were consistently clearer and better pictures than the right hand even though they were right handed

Question 20

What do the findings for the drawings of the left hand demonstrate?

Answer 20

The superiority of the right hemisphere when it comes to visual motor tasks

Question 21

What were the findings for the right hand in the drawing task? (controlled by the left hemisphere)

Answer 21

They attempted to draw a picture but it was never as clear as the left hand

Question 22

What are strengths of split brain research?

Answer 22

Highly controlled laboratory research - replicated

Question 23

What are weaknesses of split brain research?

Answer 23

• very limited sample size (sperry used 11 RPS)

- Patients had epilepsy - limits generalisability to healthy people

Question 24

What is the main problem of split brain research?

Answer 24

Lacks ecological validity - in real life, patient use both eyes to compensate for the disconnection between the two hemispheres

Question 25

What is the issue with replication?

Answer 25

Split brain patients are rare

Question 26

What are the issues with the patients used in Sperry’s research?

Answer 26

• They had epilepsy which means the results have limited generalisability to healthy population
• Some patients were also taking medication
• Surgery was more severe in some patients
• Small sample size used

Question 27

Does split brain research take an idiographic or nomothetic approach? Why?

Answer 27

Idiographic
Some psychologists argue that Sperry’s research is just a collection of case studies which means general laws cant be created