hemispheric lateralisation

Question 1

what is hemispheric lateralisation?

Answer 1

-the idea that the two hemispheres of the brain are functionally different and that certain mental processes are and behaviours are mainly controlled by one hemisphere rather than the other.

Question 2

What are examples of functions/ areas that are NOT lateralised?

Answer 2

-vision, motor and somatosensory areas appear in both hemispheres

Question 3

What is an example of a function/ area that is lateralised?

Answer 3

-language is only on the left side

Question 4

What does contralateral wiring mean? What function is wired contralaterally?

Answer 4

-the right hemisphere controls the left side whilst the left hemisphere controls the right side
-motor area

Question 5

R or L? Controls the left side of the body.

Answer 5

-L/ Left Hemisphere

Question 6

R or L? Viewing objects visible in the left visual field

Answer 6

-R/ Right Hemisphere

Question 7

True or False? The right hemisphere helps us produce and understand
language

Answer 7

False! The Left hemisphere does this :)

Question 8

L or R? Is the synthesizer.

Answer 8

R/ Right Hemisphere

Question 9

L or R? Is the analyser.

Answer 9

L/ Left Hemisphere

Question 10

True or False? The right hemisphere focuses on the wider visual picture, while the left hemisphere focuses on the finer image details.

Answer 10

True!!

Question 11

What is ‘split-brain’ research?

Answer 11

-research on those that had a a commissurotomy performed on them
-a commissurotomy is surgical procedure that cuts through the corpus callosum (which connects the two hemispheres together) and is used as a way to control epileptic seizures

Question 12

What was the aim of Sperry’s (1968) research?

Answer 12

-to study how two separated hemispheres deal with, for example, speech and vision

Question 13

What were the procedures of Sperry’s (1968) research?

Answer 13

-11 people who had a split-brain operation
studied using a special set up in which an image could be projected to a participant’s RVF (processed by the LH) and the same, or different, image could be projected to the LVF (processed by the RH).
-Presenting the image to one hemisphere of a split-brain participant meant that the information cannot be conveyed from that hemisphere to the other.

Question 14

What were the findings of Sperry’s (1968) research?

Answer 14

-When a picture of an object was shown to a participant’s RVF, the participant could describe what was seen. But they could not do this if the object was shown to the LVF- they said there was ‘nothing there’.
-This is because, in a connected brain, messages from the RH are relayed to the language centres in the LH, but this is not possible in the split-brain.
-Although participants could not give verbal labels to objects projected to the LVF, they could select a matching object out of sight using their left hand (linked to RH).

Question 15

What was concluded from Sperry’s research?

Answer 15

-certain functions are lateralised in the brain
-supports the view that the LH is verbal and the RH is ‘silent’ but emotional.

Question 16

What are the strengths of hemispheric lateralisation?

Answer 16

-shows us how having two hemispheres of the brain that function differently is adaptive
-Sperry’s research has good methodology

Question 17

What are the limitations of hemispheric lateralisation?

Answer 17

-overemphasis and oversimplification
-can have negative consequences

Question 18

Explain the strength of hemispheric lateralisation that it shows us how having two hemispheres of the brain that function differently is adaptive?

Answer 18

-For example, research by Rogers (2004) showed that lateralized chickens could find food whilst watching for predators, but normal chickens could not.
-In addition, certain lateralized brain functions may be moved or redistributed rather than lost following damage or trauma to the brain.
-For example, Holland (1996) found that language function can literally ‘switch sides’.
-This shows that having two hemispheres is useful and can aid survival

Question 19

Explain the strength of hemispheric lateralisation that Sperry’s research has good methodology?

Answer 19

-Specialist equipment: a tachistoscope- scientific equipment that provided accurate, reliable data and meant that the procedure could be replicated by others.
-Quasi-experiment: meant that Sperry had took advantage of the pre-existing independent variable, the fact that they already had a split-brain, therefore participants were not deliberately harmed for the
experiment, meaning that it can be considered ethical.

Question 20

Explain the limitation of hemispheric lateralisation that there is overemphasis and oversimplification?

Answer 20

-There can be oversimplification when referring to functions being lateralized
-e.g. LH as ‘analyser’ and RH as ‘synthesiser’ or
referring to people showing RH or LH dominance.
-For example, Nielsen (2013) analysed brain scans of a sample of over 1000 participants and although he found that people did use certain hemispheres for certain tasks, there was no evidence of a dominant side.
-This suggests that the notion of ‘right’ or ‘left’
brained people is incorrect; in the normal brain the two
hemispheres are in constant communication when performing everyday tasks, and many behaviours typically associated with one hemisphere can be effectively performed by the other when the situation requires it.

Question 21

Explain the limitation of hemispheric lateralisation that it can have negative consequences?

Answer 21

-This is supported by a condition names ‘Alien Hand Syndrome’ where the hand functions separately from the rest of the body-because the brain is split, there is no communication between the hemispheres to co-ordinate movement.
-This evidence shows that there can be significant consequences of split-brain surgeries
-This is a limitation because it can often impact daily life, making it significantly harder to live ‘normally’.

Question 22

Explain the limitations of Sperry’s Research/ the counterpoint to the strength about Sperry having good methodology?

Answer 22

-generalizability issues, and some unethical aspects
-behaviour of split-brain participants was compared to a neurotypical control group, none of which had epilepsy, which is a major confounding variable.
-This is because any differences observed between the two groups may have been the result of epilepsy rather than the split-brain.
-In addition, the trauma of the operation may mean that the participants did not later fully understand the
implications of what they agreed to- they were subject to repeated testing over a lengthy period of time.
-This raises the ethical issue of fully informed consent and psychological harm.