Hemispheric Lateralisation

Question 1

What is lateralisation?

Answer 1

Some mental processes are specialised to either the right or the left hemisphere as they have different functions

Question 2

Right brain function

Answer 2

Synthesiser
- controls the left side of the body & gathers information from the left visual field
- creativity & context of what is being said
- recognition of faces, place, objects
- spontaneous

Question 3

Left brain function

Answer 3

Analyser
- controls the right side of the body & gathers information from the right visual field
- speech & language
- recognition of words, letters, numbers, etc.
- logical, rational and calculating

Question 4

:( May lack generalisability across age groups

Answer 4

Szaslarski et al (2006): language became more lateralised to the left hemisphere with increasing age but after 25 y/o, lateralisation started to decrease by the decade
- lateralisation of language is not fixed permanently

Question 5

** :( Nielsen et al (2003)**

Answer 5

Analysed brain scans from over 1000 people between 7-29 years y/o and found that certain hemispheres operated certain tasks but there was no evidence for a dominant side.

Question 6

:) Rogers et al (2004)

Answer 6

Lateralised chickens could find food while watching for predators in comparison to non-lateralised chickens
- this is evolutionary adaptive

Question 7

:) Fink et al (1996)

Answer 7

Used PET scans to research which hemisphere was active during visual processing tasks
- when pts were tasked with a whole photo, the right hemisphere was more active
- when pts were tasked with finer details, the left hemisphere was more active

Question 8

:) Split brain research

Answer 8

Sperry:
- 11 patients who recieved surgery where their corpus callosum to reduce seizures
- created 3 tasks for pts to complete to assess hemispheric lateralisation

Gazzaniga:
- split-brain pts performed better than connected control patients on certain tasks
- suggested that in the connected brain, cognitive strategies in the left hemisphere are “watered-down” by the right hemisphere

Question 9

Split Brain procedure

Answer 9

Task 1: describe what you see
Presented to the RVF (LH): participants could easily describe what they has seen
Presented to the LVF (RH): couldn’t describe what was seen and often said nothing was present

Task 2: tactile test
Object in right hand (LH): pts could describe what was in their hand and could identify the object
Object in left hand (RH): pts could not describe what was in their hand however could identify the object

Task 3: drawing task
Picture presented to the RVF and drawn by the right hand (LH): drawings were not clear
Picture presented to the LVF and drawn by the left hand (RH): drawings were clear