6.3.2 Hemispheric lateralisation

Hemispheric lateralisation: The idea that the two hemispheres perform different functions and each hemisphere is mainly responsible for certain behaviours

• Spatial skills are hemispherically lateralised to the right hemisphere
• Language skills are hemispherically lateralised to the left hemisphere

Organised contralaterally:

The left hemisphere controls the right side of the body, and the right hemisphere controls the left side of the body

e.g. movement, vision and touch are organised contralaterally

The two hemispheres are connected by the corpus callosum

Corpus callosum: A bundle of nerve axons that enable communication between the two hemispheres

Sperry's split-brain research:

Split brain patients:

Someone who has had their corpus callosum cut

Sperry conducted split-brain research on epileptic patients who had a commissurotomy (corpus callosum cut).

• Research support for hemispheric lateralisation

1. Image or word was presented to the patient's right visual field, and so would be processed by the left hemisphere. Another image or word was presented to their left visual field, and so would be processed by the right hemisphere
2. Patients were then asked to respond to the stimulus (either by describing it verbally or by pointing to the stimulus that matched the one they were shown).

Findings:

Found that patients could only describe an image verbally if it was presented to their left hemisphere (right visual field), suggesting that the left hemisphere is responsible for language skills

When a word was presented to the right hemisphere (left visual field), patients were able to write it down, but unable to say it, suggesting that the right hemisphere is responsible for spatial skills

Evaluation:

(1)

(2)