lateralisation and split brain research

Question 1

define lateralisation

Answer 1

dominance of one hemisphere of the brain for particular physical and psychological functions

Question 2

what is the corpus callosum and what is it’s function

Answer 2

• bundle of nerve fibres that connect brain hemispheres
• allows information received from one hemisphere to be sent to the other hemisphere

Question 3

outline the procedure of Sperry’s research into split-brain patients

Answer 3

• quasi experiment with 11 split-brain patients
• performance of tasks compared with control
• blindfold pps and get them to fixate on a spot in middle of screen
• stimulus projected in RVF or LVF for less than a second
• when stimulus presented to LVF of a split-brain patient, they should not be able to name it

Question 4

outline the main findings of Sperry’s research

Answer 4

• patients can verbalise image shown to RVF
• cannot verbalise image shown to LVF but can draw it with their left hand
• if image shown in both visual fields, they will say they’ve seen it in RVF but draw image seen in LVF with their left hand

Question 5

EVALUATION
advantages of hemisphere lateralisation

Answer 5

• assumed it increases neural processing capacity
• little empirical evidence to show lateralisation confers any advantage to the brain functioning
• some support - Rogers found chickens can perform two tasks simultaneously (finding food and being vigilant for predators)

Question 6

EVALUATION
lateralisation changes with age

Answer 6

• appears not to stay exactly the same throughout a lifetime
• lateralised patterns found in younger individuals tend to switch to bilateral patterns in healthy older adults
• szaflarski found lateralisation decreased after the age of 25
• one possibility is that using the extra processing resources in the other hemisphere may compensate for age-related declines in function

Question 7

EVALUATION OF SPLIT BRAIN
language may not be restricted to the left hemisphere

Answer 7

• Gazzaniga suggests early discoveries from split brain research have been disconfirmed
• split brain research found right hemisphere couldn’t handle most basic language
• however, case studies have demonstrated people can develop the capacity to speak out of the right hemisphere

Question 8

EVALUATION OF SPLIT BRAIN
limitations of split-brain research

Answer 8

• procedure is rarely carried out
• patients who have had this procedure are rarely encountered in sufficient numbers
• claimed that conclusions are drawn from individuals who have either a cofounding physical disorder or who had a less complete sectioning of two hemispheres

Question 9

EVALUATION OF SPLIT BRAIN
sperry’s research

Answer 9

• well designed with standardised procedures and so properly controlled which hemisphere was being exposed and procedure could be replicated
• he used small sample sizes so we can’t generalise