hemispheric lateralisation

• What is hemispheric lateralisation?

  Lateralisation is the idea that the two halves of the brain are functionally different and that each hemisphere has functional specialisations.
• What is the visual field?

  The visual field refers to the total area in which objects can be seen in the side (peripheral) vision as you focus your eyes on a central point.
• What is the visual cortex?

  The visual cortex is a part of the brain that allows vision.
• What is the corpus callosum?

  The two hemispheres are connected through nerve fibres called the corpus callosum, which facilitate interhemispheric communication: allowing the left and right hemispheres to 'talk to' one another.
• What is the left hemisphere responsible for?

  Language and right side bodily control
• What is the right hemisphere responsible for?

  Face recognition and left side bodily control
• What did Sperry investigate?

  The neurological, behavioural and psychological effects of disconnecting the hemispheres by severing the nerve fibres (corpus callosum) which join them (split-brain procedure).
• Why did some patients have their corpus callosum severed?

  This procedure was used on people with severe epilepsy to stop seizures spreading across the two hemispheres. Cutting the corpus callosum stops any cross-talk between the hemispheres
• What research method did Sperry use?

  Quasi-lab experiment
• Who were Sperry's participants?

  11 patients with epilepsy who had their corpus callosum compared to 11 without epilepsy
• What was the main procedure of Sperry?

  Sperry devised a procedure whereby patients had to focus on a dot and an image or word would be projected to either their right visual field or left visual field.
• What other methods did Sperry use?

  There were also tactile tasks (tasks with objects) were carried out with the patients hands underneath a screen so the patients themselves couldn't see what they were doing. They had to use 'feel' only.
• What happened when one object was presented to their LVF and one to their RVF?


  They could say the one presented to their RVF but not their LVF
• What happened when they were shown an object in their LVF, which hand were they be able to find it with?

  Left
• What happened when they were shown an object in their LVF, were they able to say what the object was?


  No
• When happened when a patient was shown two different words to the left & right visual fields, which did they say?

  The object presented to the RVF
• When happened when a patient was shown two different words to the left & right visual fields, which did they pick up with their right hand?

  The object presented to the RVF
• When a female face in on the left, and a male face on the right - did they say they had seen a man or a woman?


  Man
• When a female face in on the left, and a male face on the right, which did they say they had seen from a line up?

  Woman
• What issues with generalisability were there in Sperry's study?

  These patients had epilepsy which may have caused changes to their brain, making them different from the general population.
• How is the reliability considered in Sperry's study?

  Standardised procedures. Made replication possible to check reliability. Scientific research
• What are real life applications of Sperry's study?

  'Split-brain' research has enabled discoveries of lateralisation of function and which functions are lateralised. Research has added to the unity of consciousness debate.
• How is the internal validity considered in Sperry's study?

  Controlled conditions: Can control what information goes to which hemisphere which allows for better understanding of lateralisation of function.
• What issues did Sperry's study have in terms of internal validity?

  Issues with control: extent of disconnection between hemispheres varied, lack of valid control groups, may be additional effects of surgery other than just procedure, some patients had experienced drug therapy for much longer than others
• How is the ecological validity considered in Sperry's study?

  Low in ecological validity: In real life, patients can move their head so information goes into both hemispheres.