(brain) hemispheric lateralisation & split-brain research AO3

Question 1

1) (+) lateralisation connected in brain

Answer 1

P: research showing even in connected brains, the 2 hemispheres process info differently

E: eg. fink et al. 1996 - used PET scans to identify which brain areas active during visual processing task
- when ppts with connected brains asked to attend to global elements of image (eg. pic of whole forest), regions of RH more active
- when required to focus on finer detail (eg. individual trees), specific areas of LH tended to dominate

E/L: suggests, as far as visual processing concerned, hemispheric lateralisation is feature of connected & split-brain

Question 2

2) (-) one brain

Answer 2

P: limitation is idea that the LH is analyser & RH is synthesiser may be wrong

E: may be diff. functions in RH/LH, but research suggests people don’t have dominant side of brain which creates diff. personalities
- nielsen et al. (2013) analysed brain scans of 1000+ people aged 7-29 years & did find people used certain hemispheres for certain tasks (lateralisation) but no evidence of dominant side

E/L: suggests idea of right/left-brained people is wrong

Question 3

EXTRA 3) (+) lateralisation vs. plasticity

Answer 3

P: lateralisation vs. plasticity

E/E/L:
- lateralisation is adaptive as enables 2 tasks to be performed simultaneously with larger efficiency eg. rogers et al. (2004) showed lateralised chickens find food while watching for predators but ‘normal’ chickens couldn’t
- on other hand, neural plasticity also seen as adaptive - eg. following damage via illness/trauma, some functions taken over by non-specialised areas in opposite hemisphere (eg. language function switch sides - holland et al. 1996)

Question 4

4) (+) research support for sperry’s research

Answer 4

P: support from more recent split-brain research

E: eg. gazzaniga (luck et al. 1989) showed split-brain ppts perform better on certain tasks - eg. faster at identifying odd one out in array of similar controls
- in normal brain, LH’s better cognitive strategies ‘watered-down’ by RH (kingstone et al. 1995)

E/L: supports sperry’s findings that LH & RH are distinct

Question 5

5) (-) generalisation issues of sperry’s research

Answer 5

P: casual relationships hard to establish

E: behaviour of sperry’s split-brain ppts compared to neurotypical control group - one issue is none of ppts in control group had epilepsy (major confounding variable) so any diff. between could be result of epilepsy & not split-brain procedure

E/L: means some of original features of split-brain ppts cognitive abilities may be due to epilepsy

Question 6

EXTRA 6) (+/-) ethics

Answer 6

P: split-brain op not performed for purpose of research

E/L:: means sperry’s ppts not deliberately harmed - also, all procedures explained & full-informed consent obtained

counterpoint E/L: although, trauma of op may mean ppts didn’t later fully understand what they’d agreed to & subject to repeated testing over long period which may have been stressful