split brain research and hemispheric lateralisation ao1 Flashcards
left hemisphere
language processing
broca and wernikes area
rational logica problem solving
right hemisphere
spatial facial and emotional recognition
recognising emotions in others
left visual field processing by your right hemisphere
who and did case study to supoort right hemisphere fuction
heller and levy 1981
heller and levy 1981
studied reognition of emotions of othes
if a photo of a face has been split so that one half is smiling and other is neutral - the emotion displayed on the left side of the picture is the emotion recognised by the ppt
the left visual field has stated the left side is neutral - controlled by right hemisphere due to contralateralisation
Who studied lateralisation of the brain
Sperry
What connects right and left hemisphere
Corpus Callosum
All of sperrys patients have
Epilepsy
had their corpus callosums severed (commissurotomy) - to control their severe epileptic seizures
Purpose of corpus callous 1940
Was to hold hempipsheres of brain together and share info bet hemispheres
Left visual field is …
And is controlled by …
Left side of both eyes
Right hemisphere
Right visual field is …
And is controlled by …
Right side of both eyes
Left hemisphere
Left hand is controlled by
Right hemisphere
Right hand is controlled by
Left hemisphere
Who studied laterisation
Sperry and gazzaniga 1976
S and G aim
To test the capabilities of the Seperated hemispheres by sending visual field imagery to just one hemisphere
S and g procedure
Person would fixate on dot at centre if screen
Info was presented to their left or right visual field
They would then make responses with either thier right or left hand
Or verbally (controlled by left hemisphere()
They were unable to see what their hands are doing
S and G sample
Type of experiment
DV and IV
All had comminssorotomy surgery to cut corpus callosum
11pateints
Quazi experiment - naturally occurring
IV - did they have a split brain or not
DV- performance in visual or tactile tasks
s and g - describe what you see
When a picture was shown to the right visual field the patient could easily describe what was seen because rvf controlled by lh which contains language centres
If the same image was shown to the left visual field controlled by rh they reported that there was nothing there or couldnt say what they saw bc rh doesnt have language centres
normally 2 hemispheres can communicate this cannot occur in split brain patients so rh unable to verbalise what was seen
Findings of s and g
Describe what you see
Recognition by touch
if Although patients could not attach verbal labels to objects projected in the left visual field (but could with their right) - they were able to select a matching obj from a grab bag of different object using their left hand (connected to rh)
if they coudnt find exact item they could pick our something the most similar eg one patient had a cig flashed up - they picked up an ash tray -couldnt say cig
Findings of s and g - composite words
If 2 words were presented simultaneously on either side of the visual field for example key on the left and ring on the right the patient could draw a key w left hand and then say the word key bc left hand connected to rh that has creative drawing capabilities
and say the word ring bc it was presented to rvf controlled by lh which contains lang centres
Findings of s and g - matching faces
The right hemisphere also appperaed dominant in terms of recognising faces
When asked to match a face from a series of other faces
The picture processed by the right hemisphere (shown to lvf) was consistently selected
This is bc R hem is responsible for facial and emotional recognition
Split brain patients show unusual behaviour when tested in expiriments
Briefly explain how unusual behaviour in split brain patients could be tested in an experiment (2)
Ask patients to look at dot on a screen and flash an image to their right visual field then ask them ti say what they saw
Then flash an image to their left visual field and ask them to say it
Outline findings of sperry and Gaza split bran research
When a picture of an object was shown to ppts RVF linked to LH they were able to describe what was seen
When ppts had image shown to LVF linked to RH they reported that there was nothing there
This is bc in a connected brain messaged from right hemisphere are relayed to language centres in left this isn’t possible in split brain
Although ppts couldn’t give verbal labels to objects linked to LVF they could select a matching object out of sight using their left hand which is linked to right hemisphere
The left hand was also able to select object most closely related with object presented to left visual field
If a pic was shown to LVF their was an emotional reaction eg giggle but reported seeing flash of light
Conclusions of sperrys split brain research
These obeservations show that certain functions are lateralised in the brain and support the veins tht LH IS verbal RH is silent yet emotional
Ao1 Karen Bryne case study
Karen had surgery to cut her corpus callosum
The side effect of which demonstrated how the 2 hemispheres work independently in a real world example
She suffers from alien hand syndrome
She describes behaviour where she would light a cigarette and the left hand would stubb it out, or her right hand would do up the buttons of her shirt only for her left hand to unbutton them
This suggests that both hemispheres work independently and may have their own consciousness
