4.2.2 - Split Brain Research Flashcards
Who carried out the split brain research
Roger Sperry
What is the process of dividing the two halves of the brain
- the corpus callosum joins the two laces of the Brian together
- a commissurotonomy is the process of the division of the two hemispheres by surgery
- a commissurtononmy was carried out on patients with severe epilepsy with the intents on to reduce their symptoms
What were sherry’s findings about the left half of the Brian
- the left hemisphere controls the right side of the body
- views objects in the right visual field
- processes language
What were Sperry’s findings about the right half of the brain
- controlling the left side of the body
- viewing objects in the left visual field
- drawing
- facial recognition
- spatial tasks
- but CANNOT process and understand language
What was the procedure of task one (visual recognition)
- ppt gazes at a fixation point on an upright translucent screen
- slides containing words or images are projected either side of the fixation point for ONE TENTH of a second
What were the findings about visual recognition
- when an object is displayed in the RVF (processed in the left hemisphere), ppts can describe the object in both speech and writing (right handed ppts)
- object displayed in LVF cannot be describes with words, instead ppts say that they have seen nothing
BUT - when asked to use the left hand to point to a matching objet on the table, ppts can do this accurately whilst still insisting that they have not seen an object
What was the procedure of task two (drawing the objects)
- two different object were displayed on the screen at once ( a different image on each VF)
- ppts were asked to draw what they see with their left hand, and say what was drawn.
What were Sperry’s findings about drawing objects
- ppts drew what was on the LEFT half of the screen because it was seen with the right brain
- ppts said hey had drawn what was on the RIGHT half of this is because language uses the left hemisphere
What was the procedure of task three ( naming objects by touch)
- ppts were shown an objects on the screen, in the LVF
- they were asked to select the matching object from a grab a bag with their LEFT hand.
What were the findings of the naming objects by touch task
- pts couldn’t attach a verbal label to the objects projected into the LVF
- they could successfully select a matching object with a grab a bag with their left hand.
What was the procedure of task 4 (composite words)
- ppts were presented 2 words simultaneously on both visual fields
- they were asked to select the object they have read from a grab a bag and also say what they have selected
What were the findings of composite words task
- ppts selected the object corresponding to the word on the LVF, but said they have selected the word on the RVF
What did sperry find out from facial recognition
- the right hemisphere dominates when matching faces
-> when faces are shown to the LVF, it is sent to the right hemisphere and the correct matching picture is selected.
-> when shown to the RVF, it is sent to the eft hemisphere and the matching picture is not selected
When using a composite picture each hemisphere sees half a face
- the RVF goes to left brain so a verbal description can only be given
- the LVF goes to the right bran so a matching picture is able to be selected
What were the conclusions that Sperry drew after his research
- when we separate the hemispheres, we can clearly see that they act differently and perform different functions
- the RIGHT hemisphere can recall and identify stimuli, but cannot verbalise this
- the LEFT hemisphere is specialised for speech and writing
Split brain research A03: small sample size
limitation
- Sperry only used 11 split brain patients, some of which had a more lateralised brain than others
- individual differences could therefore have an effect on the results
