| What does lateralisation mean? | The idea that two hemispheres are functionally different and that certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other. |
| why is language lateralised? | The Broca’s area and the Wernicke’s area are both located in the LEFT hemisphere ONLY |
| Why is movement not lateralised? | Both the left and right hemispheres are involved with movement
The RH controls activity on the left side of the body whilst the LH controls movement on the right side. This is called contralateral wiring (cross-wired). |
| Why is vision not lateralised? | Both the left and right hemispheres are involved with vision
Each eye receives light from the left visual field (LVF) and the right visual filed (RVF). The LVF of both eyes is connected to the RH and the RVF of both eyes is connected to the LH. The is called contralateral and ipsilateral (opposite and same-sided) |
| Strength of hemispheric lateralisation? | -Supporting research
-Eg: Fink et al used PET scans to identify which brain areas were active during a visual processing task. When ppts with connected brains were aksed to attentd the global elemtsn of an imgage regions of the RH were more active
-When required to focus on the finer details areas of LH tended to dominate. Significant bc it shows that even in connected brains the hemispheres process info differently
-Suggests, at least as far as visual processing, hemispheric laterlisation is a feature of a connected brain as well as split-brian |
| A weakness of hemispheric lateralisation? | -Idea that LH is the analyser and RH is the synthesiser may be wrong
-Nielsen et al analysed brian scans from over 1000 people aged 7-29 years and did fid that people used certain hemispheres for certain task. No evidence of domaniant side
-Shows there may be different functions in the RH and LH, but the reseach suggests that we do not have a dominate side of the brain that creates a different personality
-Suggests that the idea of someone being right or left brained as wrong. |
| Why are there splitbrain people | ppl with epilesphy had surgical separation of the hemispheres of their brain to reduce the severity of their epilepsy.
Enabled researchers to test lateral functions of the brain in isolation. |
| What was Sperry procedure? | 11 ppl with split-brain operation studied using a selt up which could protect images into someone RVF and the same, or different, image projected to the LVF. |
| Why was this procedure chosen for split-brain research? | -Normal brain, the corpus callosum would share information and give a complete picture of the visual world.
-Only one hemisphere in a split-brain ppts means that information cannot be conveyed |
| Findings of Sperry about RVF and LVF? | -Shown to RVF, ppts could describe, not in LVF
-Shown to LVF, they could slect a matching object out of sight using thier left hand. Object closely associated with the object |
| What is happens when a pin up picture is seen? | Seen in the LVF, emotional reaction like gigle - but pps usually reported seeing nothing |
| Conclusion of Sperry? | Cerrtain functions are lateralised in the brain and support the view that the LH is verbal and the RH is ‘silent’ but emotional. |
| Strength of split-brain research? | -Supporting research
-Gazzaniga shows split-brain ppts atually perfrom better than connected controls on certain task. Eg: faster at identifying the odd one out in an array of similar objects
-Significant bc the fact that other researchers can replicate similar findings incrase external valdity of Sperry and imprvoes the temporal validty as they are drawing the same conclusions
-Supports Sperry's earlier finding of 'left brain' and 'right brain' being distinct |
| A weakness of split-brain? | -causal relationship hard to establish
-Behaviour in Sperry's split-brain ppts were compared to a neurotypical control group. An issues though is that none of the ppts in the control group had epilepsy
-Significant bc this was a confounding variables, differnece betwen the groups could have been a result of epilepsy rather than split brain
-means that some of the unique features of the split-brain ppts' congitive abilites may have been due to their epilespsy. |
