Hemispheric Lateralisation + Split-Brain Research

Question 1

What is hemispheric lateralisation?

Answer 1

idea that the two hemispheres are specialised for different functions- left hemisphere is typically responsible for language, and the right hemisphere for spatial tasks and facial recognition.

Question 2

What is the corpus callosum and its role in the brain?

Answer 2

The corpus callosum is a bundle of nerve fibres that connects the two hemispheres, allowing communication between them. In split-brain patients, this is severed to reduce epileptic seizures, isolating the two hemispheres.

Question 3

What was the aim of Sperry’s split-brain research?

Answer 3

to investigate the extent to which the two hemispheres have separate functions by studying patients who had undergone commissurotomy (severing the corpus callosum) to treat epilepsy.

Question 4

What was Sperry’s method in split-brain studies?

Answer 4

Participants were shown images to one visual field (left or right) and asked to respond verbally or physically. Because visual information is processed contralaterally, this tested each hemisphere independently.

Question 5

What were Sperry’s key findings?

Answer 5

When images were presented to the left visual field (processed by the right hemisphere), patients couldn’t name the object. However, they could draw or select it using their left hand = left hemisphere is responsible for language, and the right for visuospatial processing.

Question 6

strength- High internal validity due to controlled methodology

Answer 6

Sperry’s research used highly controlled procedures = precise measurement of each hemisphere’s functions. For example, visual stimuli were flashed to either the left or right visual field for less than 1 sec to prevent information crossing hemispheres via eye movement. This level of control made it possible to isolate the input to a single hemisphere and directly observe its processing abilities. Such methodological rigour increases the internal validity of the findings, making the conclusions about hemispheric lateralisation more scientifically robust.

Question 7

weakness- low external validity

Answer 7

study involved only 11 ppts, making it difficult to generalise findings to wider population- brains do not represent typical functioning. this reduces validity as results may not accurately reflect how lateralisation works typically= weakens overall applicability= limits comprehensive explanations

Question 8

weakness- inaccurate explanation

Answer 8

idea of hemispheric dominance may not be that accurate. research shows certain tasks use specific hemispheres but there is no evidence that people have dominant sides for personality. this challenges the left-right brain notion as the function is more integrated= does not support hemispheric dominance

Question 9

strength- scientific contributions

Answer 9

Sperry’s findings provided significant insight into how certain cognitive functions are lateralised in the brain - the research demonstrated that the left hemisphere = language, right = visuospatial tasks. These discoveries had a lasting theoretical impact, helping to establish the principle of hemispheric specialisation. They also influenced modern neuropsychology and our understanding of how different brain regions coordinate complex behaviour, especially after injury or surgery= deepened understanding