BIO 08 (part a) - Hemispheric lateralisation

Question 1

What is hemispheric lateralisation?

Answer 1

The idea that two halves of the brain are functionally different, and that certain mental process and behaviours are mainly controlled by one hemisphere e.g. language (which is localised as well as lateralised)

Question 2

What functions are lateralised in the left hemisphere?

Answer 2

• Language
• Analyser
• Controls movement of right side of the body
• Processes info from the right visual field
• Finer image details

Question 3

What functions are lateralised in the right hemisphere?

Answer 3

• Emotional processing
• Synthesiser
• Controls movement of left side of the body
• Processes info from the left visual field
• Drawing
• Wider visual picture (global processing)

Question 4

What are the strengths of hemispheric lateralisation?

Answer 4

Research shows the two hemispheres process information differently

Question 5

What research evidence is there for the two hemispheres processing information differently?

Answer 5

• One strength is research showing that even in connected brains the two hemispheres process information differently
• For example, Gereon Fink et al. (1996) used PET scans to identify which brain areas were active during a visual processing task
• When participants with connected brains were asked to attend to global elements of an image (such as looking at a picture of a whole forest) regions of the RH were much more active
• When required to focus in on the finer detail (such as individual trees) the specific areas of the LH tended to dominate
• This suggests that, at least as far as visual processing is concerned, hemispheric lateralisation is a feature of the connected brain as well as the split-brain

Question 6

What are the limitations of hemispheric lateralisation?

Answer 6

The idea that LH as analyser and RH is synthesiser may be wrong

Question 7

How is the idea that LH as analyser and RH is synthesiser wrong?

Answer 7

• One limitation is the idea that the LH as analyser and RH as synthesiser may be wrong.
• There may be different functions in the RH and LH, but research suggests people do not have a dominant side of their brain which creates a different personality
• Jared Nielsen et al. (2013) analysed brain scans from over 1000 people aged 7 to 29 years and did find that people used certain hemispheres for certain tasks (evidence for lateralisation)
• But there was no evidence of a dominant side, i.e. not artist’s brain or mathematician’s brain
• This suggests that the notion of right- or left-brained people is wrong