4.2.2 - Split Brain Research

Question 1

Who carried out the split brain research

Answer 1

Roger Sperry

Question 2

What is the process of dividing the two halves of the brain

Answer 2

• 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

Question 3

What were sherry’s findings about the left half of the Brian

Answer 3

• the left hemisphere controls the right side of the body
• views objects in the right visual field
• processes language

Question 4

What were Sperry’s findings about the right half of the brain

Answer 4

• 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

Question 5

What was the procedure of task one (visual recognition)

Answer 5

• 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

Question 6

What were the findings about visual recognition

Answer 6

• 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

Question 7

What was the procedure of task two (drawing the objects)

Answer 7

• 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.

Question 8

What were Sperry’s findings about drawing objects

Answer 8

• 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

Question 9

What was the procedure of task three ( naming objects by touch)

Answer 9

• 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.

Question 10

What were the findings of the naming objects by touch task

Answer 10

• 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.

Question 11

What was the procedure of task 4 (composite words)

Answer 11

• 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

Question 12

What were the findings of composite words task

Answer 12

• ppts selected the object corresponding to the word on the LVF, but said they have selected the word on the RVF

Question 13

What did sperry find out from facial recognition

Answer 13

• 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

Question 14

What were the conclusions that Sperry drew after his research

Answer 14

• 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

Question 15

Split brain research A03: small sample size

Answer 15

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

Question 16

Split brain research A03: reductionism

Answer 16

limitation
- Sperry’s work is reductionist explanation for human behaviour as subsequent work has suggested that both the left and right hemispheres are involved in everyday tasks
- the concept of arterialisation has been taken too literally

Question 17

Split brain research A03: high control

Answer 17

strength
- Sperry created a well controlled and replicable standardised procedure
- the method is easy to replicate so external validity is high
- the study can easily be made more reliable.