Split brain

• what are limitations of split brain research?

  - differences in function of hemispheres exaggerated - extent of lateralisation is exaggerated e.g. left hemisphere is specialised for language but right hemisphere is needed to understand the meaning or emotional tone

  - issues of generalisation - can the results be generalised to 'normal' brains?

  - control group used by Sperry had no history of epilepsy - cant tell if results are due to epilepsy or split-brain
• what are strengths of split brain research?

  - experiments involved highly standardised, specialised procedures

  - well controlled to ensure information presented to one hemisphere only

  - led to theoretical and philosophical debates about degree of communication between hemispheres (integrated system vs duality)
• what were the conclusions from research on split brain patients?

  - Sperry showed that the brain has lateralised brain functions

  - left hemisphere more geared towards analytic and verbal tasks, right hemisphere spatial tasks

  - other split brain research - right hemisphere can produce basic words and phrases and contributes to emotional and holistic content in language
• what was the results of Sperry's study for matching faces?

  - the right hemisphere also appeared dominant in terms of recognising fans

  - when asked to match a face from a series of other faces, the picture presented to by right hemisphere (left visual field) was consistently selected, while the picture presented to the left hemisphere was consistently ignored

  - when a composite picture made up of two different halves of a face was presented - one half to each hemisphere - the left hemisphere dominated in terms of verbal description whereas the right hemisphere dominated in terms of selecting a matching picture
• what was the results of Sperry's study for composite words in split brain patients?

  - if two words were presented simultaneously, one on either side of the visual field (for example, a 'key' on the left and 'ring' on the right)

  - the individual would select a key with their left hand and day the word ring
• what was the results of Sperry's study for recognition by touch in split brain patients?

  - could not attach verbal labels to objects projected in the left visual field,

  - they were able to select a matching object using their left hand (right hemisphere)
• what was the results of sperry's study when describing what you see in split brain patients?

  - picture shown to right visual field - patient easily describes

  - picture show to left visual field - patient cant describe or say nothing here

  - the objects in the left visual field are processed in the right hemisphere because of the lack of language centres in the right hemisphere

  - in the normal brain, messages from the right hemisphere would be related to the language centres in the left hemispheres
• what was the procedure of Sperry's study in split brain patients?

  - 11 split brain patients

  - patients given a 'fixation point' to look at on a screen

  - image or word is presented to either the left visual field (left eye) or right visual field (right eye)

  - the information cant be transferred from one hemisphere to another and therefore you can see the function of each hemisphere in isolation
• what was Sperry's study on split brain patients?

  - studies split-brain patients who had an operation where the corpus callocum is cut in order to separate the two hemispheres

  - allows to see how the hemispheres are specialised for different functions as they cant communicate with each other
• what is split brain research?

  studies looking at epileptic patients who have experienced surgical separation of the hemispheres of the brain
• what is hemispheric lateralisation?

  the idea that the two halves of the brain are functionally different and some mental processes are mainly controlled by one hemisphere
• what is the function of the right hemisphere?

  - spatial hemisphere

  - face recognition

  - music
• what is the function of the left hemisphere?

  - language

  - computation

  - logical reasoning