Biopsychology - Lateralisation

Question 1

Intro to hemispheric lateralisation

Answer 1

Idea that the two halves of the brain have different functions
Left hemisphere: dominant for language
Right hemisphere: dominant for visual and motor tasks - facial recognition

Question 2

Corpus callosum

Answer 2

Bundle of nerve fibres connecting the two hemispheres
Facilitates communication between left and right sides

Question 3

Split-brain patients

Answer 3

Individuals who have undergone commissuritomy
Procedure severs the corpus callosum
Used as a treatment for severe epilepsy
Provides unique opportunity to study hemispheric specialisation

Question 4

Sperry and gazzaniga’s split-brain research

Answer 4

Pioneering studies on split-brain patients
Aimed to examine hemispheric lateralisation
Used various tasks to test each hemisphere separately
Images presented to left or right visual field
Left visual field = processed by right hemisphere
Right visual field = processed by left hemisphere
Left field/right hemisphere: cannot describe verbally
Right field/left hemisphere: can describe verbally

Question 5

Tactile test

Answer 5

Objects placed in left or right hand
● Left hand → processed by right
hemisphere
● Right hand → processed by left
hemisphere
● Results:
● Left hand: Can’t describe, but can identify similar object
● Right hand: Can describe and identify

Question 6

Drawing task

Answer 6

Pictures presented to left or right visual field
● Patients asked to draw what they saw
● Results:
● Left hand (right hemisphere): Clearer, better drawings
● Right hand (left hemisphere): Less clear drawings

Question 7

Summary of findings

Answer 7

● Left hemisphere: Superior in language tasks
● Right hemisphere: Superior in visual-spatial tasks/facial recognition
● Each hemisphere has unique capabilities

Question 8

Implications and applications of split-brain research

Answer 8

● Better understanding of brain function
● Insights into language processing
● Potential for targeted therapies
● Challenges “dominant hemisphere” misconceptions

Question 9

Evaluation:

Answer 9

Strengths:
Highly scientific- high controlled lab exp, presented info 1/10th second - standardised

Weakness:
Extraneous variables - variation in disconnection of corpus callosum, lack of control group (all patients suffered from epileptic seizures but control didn’t), some experienced drug therapy longer than others (affects brains ability)
Small sample - epilepsy may have caused changes in the brain - may affect findings, not representative of wider population, limited, not generalisable

Question 10

Contradictory findings: split-brain revisited

Answer 10

Turk - JW: developed capacity to speak out of right hemisphere