Brain lateralisation

Question 1

What is brain lateralisation?

Answer 1

The idea that some mental processes are specialised to either the right/left hemisphere and perform various functions in the brain.

Question 2

What does localisation mean?

Answer 2

Specific functions are located in specific parts of the brain.

Question 3

Function of right hemispshere?

Answer 3

Spatial skills
Creativity
Recognition of faces
Emotional context

Question 4

Function of the left hemispshere?

Answer 4

Language
Speech
Recognition of words/letters

Question 5

How do the two hemispsheres communciate?

Answer 5

Via the corpus callosum, a large bundle of axons.

Act like a bridge between the two hemispheres.

—-> communicate through nerve impulses.

Question 6

Features of the right hemisphere?

Answer 6

More artistic, creative, spontaneous tasks—-> research by Corballis 2014

Question 7

Features of left hemisphere?

Answer 7

More adept to tasks, more logical and calculated

Question 8

What was Sperry’s research into lateralisation?

Answer 8

Patient shown a stimulus to either right or left hemipshere

Contraleterally oragnised to image is presented to right/left hand side.

PPTs asked to respond to stimulus by:
—-> verablly describing image
—-> identifiying image from a range of four separate images.

Question 9

What did Sperry find?

Answer 9

1 study:
PPTs were able to match the stimulus to four other images whether or not the stimulus presented to the right or left-hand side

2 study found :
PPTs had to describe images, could only perform well if the stimulus was presented on the left hemisphere.

language = hemispherically lateralised to the left hemisphere.

Question 10

Why could participants able to correctly identify the right image?

Answer 10

The ability to visually process and identify the image isn’t hemispherically lateralised.
Therefore regardless of which hemisphere the information was presented, the participant had still processed the information and could point to the correct stimulus from the choice of four.

Question 11

Evaluation 👭🏽👯‍♀️
Generalisability
Limitation :(((

Answer 11

Rare procedure
not ideal to sever corpus callosum
Only 11 ppts were used and this small number of ppts differs from public due to their unusual brain activity.

Lack generalisability

Question 12

Evaluation
Confounding variables
Limitation;(((

Answer 12

Possible ppts brain activity may differ due to the abnormal seizure activity.

Did not use a neurotypical control group

Sperry should have used a control group of ppts who had epilepsy but didn’t undergo the commissurotomy procedure to increase internal validity.

Drugs used for epilepsy may have irreversibly damaged the brain itself —-> hard to isolate exact cause.

Question 13

Evaluation: limitation :((((((
Cannot be replicated

Answer 13

Research cannot be replicated as recent studies have suggested that some language tasks can be carried out even when stimulus is shown to ppts left hand side.

Shows language isn’t lateralised to left hemisphere and research cannot support Sperry’s findings.

However, Fink conducted visual experiemnt to look at forest.

Finer details —>RH activated
More global view —-> LH activated

Question 14

Exceptions to theory:

Answer 14

Case study of EB
tumour led to removal of most of the left hemisphere

lost ability to speak
Through rehab, gained the ability to speak by the age of 8

Danelli conducted case study on EB and MRI scans compared to control group.

Found that hemispheric lateralisation can be taken over by other hemisphere under certain conditions.