Zusammenfassung der Ressource
Hemispheric Lateralisation
and Split Brain Research
- LATERALISATION
- The brain is split into two equal
symmetrical parts
- Idea that the two halves
of the brain are
functionally different
and certain mental
processes are controlled
by one hemisphere
rather than the other.
- The brain is contralateral
- The left side of the body is controlled by
the right side of the brain and vice versa
- LEFT HEMISPHERE
- Language
- Two main centres for language are only in the LH
- Broca's area in the left frontal lobe
- Wernicke's area in the left temporal lobe
- If someone has a stroke on the left
side of their brain, the right side of the
body and speech is affected.
- RIGHT HEMISPHERE
- Dominant in recognising emotions in
others and spatial information
- VISION
- Both contralateral and ipsilateral
- Each eye receives light from the left visual field
and the right visual field
- LVF is connected to RH
- RVF is connected to LH
- AO3
- Research shows that even in connected
brains the two hemispheres process
information differently
- Gereon Fink et al (1996)
- Used PET scans to identify which brain areas were active during a
visual processing task. When asked to attend to global elements of
an image the RH was more active.
- When asked to point out finer details, LH dominated.
- Idea of LH as the analyser and RH as synthesiser may be incorrect.
- Nielsen et al (2013)
- Analysed over 1000 brain scans
and found that people used certain
hemispheres for certain tasks, but
no evidence of a dominant side.
- Localisation refers to the fact that some
functions are governed by specific areas
in the brain.
- SPLIT BRAIN RESEARCH
- Series of studies beginning in 1960 involving people with epilepsy who
had surgical separation of the hemispheres of their brain.
- Sperry
(1968)
- Devised a system to study how two separated hemispheres
deal with speech and vision
- Eleven people with split brain operation studied with a special set up in which an image was projected.
- Image projected to p. RVF.
- In a normal brain, the corpus
callosum would share the
information across both
hemispheres giving a complete
picture
- FINDINGS
- When a picture was shown to RVF, the participant could describe
what was seen, but could not describe it if it was shown to the LVF.
- This is because in the connected brain messages from the RH are relayed to the
language centres in LH. This is not possible in split brain.
- Although they could not give verbal labels to objects in LVF, they
could select a matching object using their left hand
- CONCLUSION
- Observation showed how
certain functions are
lateralised in the brain and
support the view that the LH is
verbal and RH is silent but
emotional.
- AO3
- Support from recent research
- Gazzaniga (1989) showed
that split brain participants
actually perform better on
certain tasks.
- E.G Faster at identifying the odd one out of an array of similar objects.
- LH cognitive strategies are not "watered down" by the RH
- Casual relationships between the two are hard to
establish
- Compared with a neurotypical control in original experiment, however none of
these people had epilepsy which caused a confounding variable.