Biological 2: Sperry

Question 0

What was the aim?

Answer 0

To study the functions of separated and independent hemispheres in the brain.

Question 1

What was the background?

Answer 1

• epilepsy= millions of brain cells firing excessively

* severe epilepsy can be cured by split of corpus callosum as confines excessive brain cells to 1 hemisphere

Question 2

What was the IV and DV?

Answer 2

IV= whether corpus callosum was cut or not

DV= the answers given/pointed to/drawn

Question 3

Who were the PPs?

Answer 3

• 11 PPs already undergone surgery to cut CC

* group of ‘normal’ people

Question 4

What were the 3 visual investigations?

Answer 4

1= image/word shown to LVF and asked to say/draw
2= image/word shown to RVF 
3= 2 different images/words shown to both hemispheres

Question 5

What were the 2 tactile investigations?

Answer 5

1= PP hands placed behind a screen and image/word projected on LVF/RVF, asked to find it 
2= left hand asked to sort array of objects by touch into shape or size or texture

Question 6

What was the shape investigation?

What was the result?

Answer 6

Array of geometric shapes, nude photo of a woman on LVF.

PP would blush, giggle, react but not know why.

Question 7

What were the results of the visual investigations?

Answer 7

1=LVF processed by RH, could be drawn but not seen
2=RVF processed by LH, could be spoken but not drawn
3= say RVF, draw LVF

Question 8

What were the results of the tactile investigations?

Answer 8

1= LVF processed by RH, could not name the object but could find by touch using LH if object had been previously placed in the same hand 
2= LH could sort objects by touch

Question 9

What were the conclusions?

Answer 9

LH=
•RH
•spoken+written language
•maths
•reasoning 
•science 

RH=
•LH
•3D
•art+music
•insight
•imagination 

Each hemisphere has it’s own memory= PP could only recognise if was presented to same hemisphere

Question 10

What were the controls used?

Answer 10

• PP asked to look at centre of screen
• covered eye not being tested
• stimulus only shown 1/10th second

^all ensured isolation of visual field

Question 11

What are some evaluations?

Answer 11

✔️ethical= informed consent, no physical or mental damage, no stress
✔️revealed important info which triggered further research
✔️controls= high internal validity

✖️all PPs epilepsy= could have affected results (small sample size)
✖️low in Eco validity as lab
✖️did not test whether dominant hand affected anything

Question 12

What are some possible improvements?

Answer 12

• test an epileptic group= PPs with corpus callosum cut not effected by it
• use a bigger+more diverse sample
• PET scan (radioactive glucose injection) after being told to do a test