Lateralisation

• How many hemispheres and lobes does the brain consist of?

  The brain consists of two hemispheres and four lobes.
• What is lateralisation in the context of brain function?

  Lateralisation refers to the control of particular psychological and physical functions by specific hemispheres of the brain.
• Which hemisphere of the brain is dominant for speech production?

  The left hemisphere is dominant for speech production and language comprehension.
• What functions are associated with the right hemisphere of the brain?

  The right hemisphere is dominant for processing emotions and controlling the left side of the body.
• What are the functions associated with the left and right hemispheres of the brain?

  Left Hemisphere:

  • Controls right side of body
  • Speech production
  • Language comprehension
  • Analytical skills
  • Logic

  
  

  Right Hemisphere:

  • Controls left side of body
  • Emotion processing
  • Creativity
  • Intuition
  • Face recognition
• What is the corpus callosum?

  A thick band of nerve fibres that connects the left and right hemispheres of the brain. It allows the two hemispheres to communicate with each other so that the whole brain can work as one complete organ
• What was Sperry's split brain research.

  • Studied 11 individuals who had their corpus callosum surgically cut in order to control epileptic seizures - this is called a commissurotomy
  • Ppts fixate on a dot in the centre if the screen whilst stimuli are presented to one half of the visual field fro 1/10th of a second so that the ppt doesn't have time to move their eyes so that both eyes see it
• What was one of the tasks of Sperry's research involving visual fields?

  Describing what you see
• In the task of describing what you see, what was shown to the participants?

  A photo was shown to either the right or left visual field
• What were participants required to do in the recognition by touch task?

  Select a matching object from a bag using their left hand
• In the recognition by touch task, which visual field were the objects shown to?

  The left visual field
• What was the task involving composite words in Sperry's research?

  Two words were presented simultaneously, one on either side of the visual field
• What were participants asked to do if they couldn't say the composite words they saw?

  Draw what they saw
• What was the task involving matching faces in Sperry's research?

  Participants were shown images of different faces and asked to match them
• In the matching faces task, how were the faces presented to the participants?

  To the left and right visual field
• What were participants asked to do in the matching faces task?

  Match the face to one from a series of other faces
• Results of recognition by touch

  They could not name the objects projected to the left visual field, but they could select a matching object with their left hand. This is because the information from the left visual field went to the right hemisphere, which is able to control the left hand and pick the matching object
• Results of composite words

  Ppts could write the word projected to the left visual field with their left hand, and could say the word projected to the right visual field. This is because the word from the right VF is processed by the left hemisphere and can be verbalised, while the word from the left VF is processed by the right hemisphere, which can control the left hand
• Results of matching faces

  The image from the left visual field was processed by the right hemisphere and was consistently selected, whilst the image from the right visual field was processed by the left hemisphere and was consistently ignored. This indicates the right hemisphere is responsible for face recognition
• Results of describing what you see

  Images projected to the right VF could be correctly named because the left hemisphere has the language abilities to name the object. However, images projected to the left VF could not be described because the right hemisphere doesn't have the language abilities and can't share it with the left hemisphere as there is no corpus callosum. This indicates language is processed by the left hemisphere
• What did Sperry and Gazzaniga's split-brain research demonstrate?

  It furthered our understanding of lateralised brain functions.
• What is the primary function associated with the left hemisphere of the brain?

  The left hemisphere is more geared towards language and analytical tasks.
• What does recent research suggest about hemispheric lateralisation?

  It may be exaggerated, as tasks associated with one hemisphere can also be performed by the other.
• Who is the patient known as J.W. in Gazzaniga's research?

  A patient who developed the capacity to speak about information presented to either hemisphere.
• What does J.W.'s ability to speak about information from both hemispheres suggest?

  It suggests that language is not solely confined to the left hemisphere.
• What is the methodology used by Sperry in his research?

  • Participants stared at a fixation point (cross).
  • An image was flashed, received only by the visual field on the same side.
  • This ensured that only one hemisphere could be tested at a time.
• What is a limitation of Sperry's sample size in his research?

  It consisted of only 11 patients, which is a small sample size.
• Why might the epilepsy of Sperry's participants affect the results?

  Epilepsy or the medication for it may have caused unique changes in each hemisphere.
• What did Rogers et al (2004) find regarding brain lateralisation in domestic chickens?

  • Brain lateralisation is associated with enhanced ability to perform two tasks simultaneously.
  • One hemisphere is used to find food while the other looks out for predators.
  • This demonstrates advantages of brain lateralisation for survival.
• How does brain lateralisation enhance cognitive tasks according to Rogers et al (2004)?

  It can enhance brain efficiency by allowing simultaneous task performance.