BIOLOGICAL: Sperry (1968)

Question 1

What was the aim of the study?

Answer 1

To investigate the effects of hemispheric deconnection on perception and memory.

Question 2

Why did sperry carry out this study?

Answer 2

Previous study shows FUNCTIONAL LOCALISATION AND LATERALISATION
Sperry believes studies involving people with split brains (underwent commissurotomy) show the true nature of the two hemispheres because they work independently.

Question 3

What is Functional LOCALISATION?

Answer 3

The limitation of particular jobs performed by particular parts of the brain.

Question 4

What is Functional LATERALISATION?

Answer 4

The idea that the two hemispheres have different functions/roles.

Question 5

What side of the brain controls language?

Answer 5

LEFT

Question 6

What side of the brain controls movement?

And what is the term to describe this?

Answer 6

Left brain controls RIGHT movement
Right brain controls LEFT movement
CONTRALATERAL CONTROL. (controlled by opposite hemisphere)

Question 7

What is COMMISSUROTOMY?

Answer 7

The cutting of structures that join the left and right side of the brain together.
structures like corpus callous and hippocampal

Question 8

What is the design of the study and why?

Answer 8

QUASI/NATURAL experiment
as IV of having a split brain is not manipulated by the researchers.

and REPEATED MEASURES as each participant was tested on left/right hemispheres.

However because of the extensive study on a small sample it can also be seen as a COLLECTION OF CASE STUDIES.

Question 9

What was the dependent variable?

Answer 9

the participants ability to perform a variety of VISUAL and TACTILE tests.

Question 10

Was there a CONTROL group?

Why?

Answer 10

NO.

Because the functions and abilities of people with no split brain is already known.

Question 11

Who was used in the study?

Answer 11

11 patients with EPILEPSY.

All had undergone operation to divide brain along CORPUS CALLOSUM to reduce spread of epileptic seizures.

Question 12

What varied amongst the participants?

Answer 12

The time they received the operation prior to the study.
eg.
one man had the operation 5.5yrs before study (the longest)
one woman had it about 4 years before study.

Question 13

Give the 6 VISUAL tasks of the procedure.

Answer 13

1) Visual stimuli presented to hemispheres SEPARATELY and then re-shown either to SAME/OPPOSITE field asked if they RECOGNISED
2) Visual stimuli presented to hemispheres SIMULTANEOUSLY and asked to draw and say what they drew without looking
3) Visual stimuli of RELATED WORDS presented to each hemisphere and asked to search for object and say what they held.
4) Visual stimuli presented SEPARATELY and asked to DESCRIBE it verbally.
5) ^same but WRITE the name.
6) ^ same but to POINT.

Question 14

What was the TACTILE task?

Answer 14

An object was placed in either left or right hand (without participants looking) and hen asked to write/say/retrieve the same object.

Question 15

What were the results of the VISUAL task?

Answer 15

1) Only recognised when the object was re-shown to the SAME visual field. (memory cannot cross the hemispheres)
2) When shown same time, could DREW what they saw in LVF and SAID what they saw in RVF.
3) Related words search: they held the object in LVF in LH but said what they saw in RVF.
4)When asked to describe: only RVF
5) When asked to write: only RVF
6) When asked to point: if shown to RVF, point with RH.
if shown to LVF point with LH (because memory cannot travel)

Question 16

What was the result of the TACTILE task?

Answer 16

When the object was placed in LEFT hand: the could only retrieve with LH

When object placed in RIGHT hand: they could retrieve with the RH but also SAY the object.

When objects placed at same time: each hand looked for their own object.

Question 17

What type of data was gathered ?

Answer 17

BOTH qualitative and quantitative.

Question 18

In what form was QUALITATIVE data gathered?

give example

Answer 18

Qualitative = descriptions of participants sensations/ transcripts of verbal response.

eg. When shown “keycase” and they said “case”, they were then asked what kind of case they had in mind.
They gave a completely different answer to keycase to show that keyless was not in thought.

Question 19

How was QUANTITATIVE data gathered?

Answer 19

YES/NO

whether participants could perform the task or not.

Question 20

What 2 conclusions on MEMORY AND PERCEPTION was made of split-brain people?

Answer 20

1) Memory is INDEPENDENT in each hemisphere; information from one visual field/hand only remembered by that hemisphere. Cannot be accessed by the other.
2) Perception is INDEPENDENT in each hemisphere; If information passes to Right hemisphere, they cannot respond in speech of writing.

AND LACK OF CROSS INTEGRATION.

Question 21

What could be improved about the control group?

Answer 21

Use a control group on non-commissurotomised EPILEPTICS.

Question 22

Was there ethical issues?

Answer 22

not about the study but about the operation itself.

Question 23

Was the study valid?

Answer 23

As it was in a LABORATORY environment, in some way yes, as extraneous variables are controlled: eg. the stimuli was only flashed for one tenth or less of a second so that the other VF could not access it.

But lacks in realism so low ECOLOGICAL VALIDITY.

Also the varying of timings of the operation could have an affect.

Question 24

Was the study reliable?

Answer 24

The procedure is a laboratory environment so yes.

Question 25

What problem is there with the sample?

Answer 25

All epileptics so cannot be generalised to those without the brain damage.
Difference in operation timing.
All english speakers so study is not ETHNOCENTRIC .
Some cultures may be less lateralised with speech function.