Outline and evaluate hemispheric lateralisation and split brain research. (16 marks)
Outline:
Each hemisphere is functionally different
Certain mental processes and behaviours mainly controlled by one hemisphere
Communicated through corpus callosum, allows perform tasks requiring both
Demonstrated by Sperry, corpus callosums removed to control epileptic seizures
Central fixation point, image one-tenth
Present to right visual field processed by left hemisphere and vice versa
Could describe images on the right, not left, language lateralised in left hemisphere
Images right drawn with right hand, left with left hand
Evaluation:
P: lacks internal validity, causal connections cannot be drawn
E: Sperry’s control group no epilepsy, differed in two ways from experimental group
A: differences due to lack of communication between hemispheres, neural changes due to
seizures or epilepsy medicines
L: only 11 studied, cannot be generalised universally
P: makes evolutionary sense
E: enhances multitasking, adaptive for humans in EEA
A: Rogers, lateralisation in chickens, find food and watch for predators simultaneously
L: valuable for neural processing capacity
P: limited, not as fixed as once predicted
E: plasticity can allow behaviours performed by one hemisphere to be performed by other
A: JW learned to describe stimuli on left
E: recovery from hemispherectomy for Rasmussen’s syndrome, plasticity effective
L: lateralisation explains some differences in brain functioning, advancements in technology
(PET) allow research into plasticity, only partial explanation
Outline:
Each hemisphere is functionally different
Certain mental processes and behaviours mainly controlled by one hemisphere
Communicated through corpus callosum, allows perform tasks requiring both
Demonstrated by Sperry, corpus callosums removed to control epileptic seizures
Central fixation point, image one-tenth
Present to right visual field processed by left hemisphere and vice versa
Could describe images on the right, not left, language lateralised in left hemisphere
Images right drawn with right hand, left with left hand
Evaluation:
P: lacks internal validity, causal connections cannot be drawn
E: Sperry’s control group no epilepsy, differed in two ways from experimental group
A: differences due to lack of communication between hemispheres, neural changes due to
seizures or epilepsy medicines
L: only 11 studied, cannot be generalised universally
P: makes evolutionary sense
E: enhances multitasking, adaptive for humans in EEA
A: Rogers, lateralisation in chickens, find food and watch for predators simultaneously
L: valuable for neural processing capacity
P: limited, not as fixed as once predicted
E: plasticity can allow behaviours performed by one hemisphere to be performed by other
A: JW learned to describe stimuli on left
E: recovery from hemispherectomy for Rasmussen’s syndrome, plasticity effective
L: lateralisation explains some differences in brain functioning, advancements in technology
(PET) allow research into plasticity, only partial explanation
