Hemispheric Lateralisation And Split Brain Research

Question 1

A03 - Case Studies

Answer 1

• Point : One limitation of split-brain case studies is the difficulty in generalising the findings to the broader population due to the unique nature of each patient’s brain and surgical differences
• Evidence: For example, commissurotomies are rare procedures today, making the study sample even smaller and less representative of typical brain function.
• Elaboration: This suggests that the results from such studies may not apply to everyone, as each brain responds differently to surgery, and the procedures involved are uncommon.
• Link: Therefore, while informative, the conclusions drawn from split-brain may have limited relevance to the general understanding of brain lateralisation, weakening their overall generalisability.

Question 2

A03 - Is the left hemisphere language dominant?

Answer 2

Point: Another limitation of previous split brain research is that it may oversimplify the concept of hemispheric dominance, particularly for language
Evidence: For example, more recent studies, such as the case of JW, has disputed the notion the only the left hemisphere is responsible for language. JW developed the ability to speak using his right hemisphere, demonstrating that both hemispheres can contribute to language
Elaboration: this finding highlight that the brain is more flexible than previously thought, and language functions are not as strictly lateralised to the left hemisphere as older theories thought
Link: Therefore, this evidence challenges the traditional view of strict hemispheric specialisation, suggesting a more complex understanding of brain function

Question 3

A03 - Changes due to Ageing

Answer 3

• Point: A limitation of lateralisation research is that the effects of lateralisation mat decrease with age, suggesting that brain function becomes more distributed overtime.
• Evidence: Szafarski et al (2006) found that in children and adolescents, the left hemisphere was dominant for language. However this dominance decreased as ppts aged, indication a reduction in lateralisation overtime.
• Elaboration: This reduction in lateralisation may serve as a compensation strategy, as the brain adapts to age-related declines in cognitive function by distributing tasks across both hemisphere.
• Link: Therefore, this evidence suggests the lateralisation is not fixed and may change with age, offering insight into the brain’s ability and challenging the idea of strict hemispheric specialisation throughout life.

Question 4

A03 - Does Lateralisation have Evolutionary Techniques?

Answer 4

• Point: One argument for brain lateralisation is that it may have provided an evolutionary advantage by improving multitasking abilities.
• Evidence: For example, Rogers eat al (2004) found that in chickens, brain lateralization allowed them to perform two tasks simultaneously—finding food while remaining vigilant for predators. This suggests that lateralization enhances cognitive efficiency by allowing different hemispheres to handle separate tasks.

Elaboration: This demonstrates that lateralization could have evolved as a way to increase brain efficiency, freeing up one hemisphere for other essential functions.

Link: However, there is limited evidence to support this evolutionary advantage in humans, making it unclear whether the same benefits apply to our species.