Hemispheric lateralisation and split-brain research

Question 1

What function occurs in both hemispheres

Answer 1

Visual:
-Visual area in left/right occipital lobe

Question 2

How is language lateralised

Answer 2

Two main centres (Broca/Wernicke’s area) only in left hemisphere
-Right hemisphere provides emotional context

Question 3

Examples of functions that are not lateralised (appear in both hemispheres)

Answer 3

Motor/somatosensory/visual areas

Question 3

How is the motor area cross-wired (contralateral wiring)

Answer 3

RH controls movement on left side of body
LH controls movement on the right

Question 4

What is a corpus callosotomy

Answer 4

Splitting LH from RH by severing corpus callosum

Question 5

What is a corpus callosotomy used for?

Answer 5

To treat epilepsy as excessive electrical activity can’t travel from one hemisphere to another

Question 6

Purpose of split-brain research

Answer 6

Study how hemispheres function when can’t communicate

Question 7

Sperry’s research 1968 procedure

Answer 7

11 split-brainers
-Image projected to right visual field (processed by LH)
-Image projected to left visual field (processed by RH)

In unsplit brain info would immediately be shared between Hs to give complete visual picture

Question 8

Sperry’s research 1968 findings

Answer 8

Picture to RVF (LH):
-could describe

Picture to LVF (RH):
-couldn’t describe as couldn’t reach language centres in LH
-BUT could select matching object with left hand (RH)
-Emotional reaction (e.g giggle) but saw nothing

Question 9

Sperry’s research 1968 conclusion

Answer 9

Certain functions are lateralised, support view that LH is language and RH is emotion

Question 10

Strength of lateralisation theory

Answer 10

Research showing lateralisation in connected brain
-e.g Fink et al (1996)- visual task with PET scan: when pps looked at whole image RH more active, when looked at small details LH more active
-Shows HL also feature of connected brain

Question 11

weakness of lateralisation theory- LH as analyser and RH as synthesiser

Answer 11

Idea of predominately left/right-brained ppl maybe wrong
-e.g Nielsen et al (2013) scans found evidence of lateralisation but not dominant side

Question 12

Strength of Sperry’s research

Answer 12

evidence from more recent split-brain studies
-e.g Luke et al: split brainers faster at identifying odd one out from similar objects
-As in normal brain= LH better cognitive strategies weakened by RH
-Shows they are distinct

Question 13

Weakness of Sperry’s research

Answer 13

Causal relationships hard to establish as confounding variables because all pps had epilepsy and that might have caused the difference, not split-brain