sperry

Question 1

describe the aim of sperrys study

Answer 1

to see if each hemisphere can function independently and if each hemisphere has its own memories and consciousnesses that is inaccessible to the other

Question 2

describe the method sperry uses

Answer 2

quasi experiment/ collection of case studies

IV: split brain or not

DV: the participants ability to perform in a series of visual and tactile tests

Question 3

describe the sample in sperrys study

Answer 3

11 split brain patients who had their hemispheres detached a a treatment for severe epilepsy

1 man had his surgery 5 years prior to the study

1 woman had hers 4 years prior

the other 9 patients had theirs at varying times, not long before the study

Question 4

describe the surgery that the participants underwent

Answer 4

patients had a commissurotomy- the surgical section of the corpus collosum, detaching both hemispheres

Question 5

describe the procedure for the visual tests

Answer 5

participants fixed their gaze on a fixed point on a translucent screen with one eye covered.

an image was then projected and then back projected at 1/10 of a second -too fast for the eyes to move- so the content only entered one visual field, so one hemisphere

Question 6

describe the procedure for the tactile tests

Answer 6

participants could reach objects but not see their hands

objects were placed in either hand or both hands

participants were then asked to either describe what was in their hands or to relocate the objects with their hands

this piece of apparatus is called a tachtistoscope

Question 7

describe the findings for the visual tests

Answer 7

information shown and responded to by one visual field could only be recognised again by the same visual field

information presented to the RVF (LH) could be described in speech or writing by the right hand. if the same information is presented to the LVF (RH) participants could not describe what they were seeing but could point with their left hand (RH) to a matching picture/object in a collection of pictures/objects.

if different figures were presented to each VF e.g a $ to the LVF and a ? to the RVF, the participant could draw the $ with their left hand but reported that theyd seen a ?

Question 8

describe the findings for the tactile tests

Answer 8

objects placed in the right hand (LH) could be described in speech or writing. if the same object was placed in the left hand (RH) participants could only guess and were usually unaware they were holding something.

objects placed in one hand could only be recognised again by that same hand

when two objects were placed simultaneously in each hand and then hidden in a pile of objetcs. each hand selected their own objects and ignored the other hands object (split brain patients were found to be quicker at this than normal)

Question 9

what did sperry conclude

Answer 9

each hemisphere as its own train of visual images

the hemispheres have a lack of cross integration where the second hemisphere doesnt know what the first hemisphere knows

each hemisphere has its own stream of consciousness and memories

Question 10

what is good and bad about the method (quasi/natural)

Answer 10

good:
-IV was not directly manipulated which makes the study more reliable and ecologically valid
-the use of a case study means lots of detailed information can be obtained so we can get a better understanding about how the brain works

bad:
-cannot be generalised to the target population due to te restricted sample size- sperry cant be sure that behaviour being displayed by participants is typical of a healthy brain
-there is a lack of control over the IV a=which may affect validity of results e.g sb patients had the operation for different lengths of time- extraneous variable

Question 11

what is good and bad about the way data was collected

Answer 11

good:
-procedure was scientific and standardised-all participants were tested in the same way which makes it reliable
-the use of control and specialised equipment limited the number of extraneous variables. sperry could be more sure he was isolating the information to one hemisphere at a time which enhances internal/experimental validity

bad:
-the task participants were asked to do and the environment in which they did it in does not represent everyday life. it can be argued that this reduces ecological validity

Question 12

comment on the ethics of the study

Answer 12

good:
-IV is naturally occurring- more ethical as participants were not manipulated for the purpose of research so PoP is adhered to
-sperry got informed consent from his participants and confidentiality was adhered to

bad:
-we may question PoP because whilst doing the tasks, participants often became embarrassed and confused

Question 13

comment in the validity of the study

Answer 13

good:
-high in experimental validity
-high in ecological validity
-not gender biased as both males and females were used- enhances population validity

bad:
-ecological validity for procedure
-population validity is low- can we generalise from epileptics (brain may have already been damaged)
-is 11 a large enough sample to generalise from

Question 14

comment on the reliability of the study

Answer 14

good:
-standardised procedure and specialised equipment were used which enhances reliability

bad:
-the sample lacked reliability as they had the operations for different lengths of time

Question 15

comment on the sampling and sample

Answer 15

good:
-opportunity sampling is the most convenient way to access the sample

bad:
-opportunity sampling can lead the sample to be unrepresentative
-11 is a small sample so it may be difficult to generalise results to the target population