Sperry (classic Study) Flashcards
Lateralisation of function
The brain has left and right hemisphere and each hemisphere has a specific function
Left hemisphere specialises in…
Language and articulation of words
Right hemisphere specialises in
Emotions and creativity
What side of the body does the left hemisphere control?
Right side:
Right hand
Right field of view
What side of the body does the right hemisphere control?
The left side:
The left hand
The left field of view
What part of the brain links the 2 hemispheres?
The corpus callosum: bundle of the nerve fibres so signals can be spread across 2 hemispheres
Why would we cut the corpus callosum and separate the 2 hemispheres?
If someone had severe epilepsy: abnormal electrical impulses that cause seizures couldn’t spread across the brain if cut
Background of this study
Sherry had worked on split brain cats, and knew that 1 hemisphere could be completely oblivious to something the other hemisphere was taught: so test on humans
Using epilepsy patients who had corpus callosum cut
Aim of this study
Map lateralisation of brain function (aka determine function of 2 hemispheres) by presenting info to only 1 hemisphere in split brain patients and determining ability in tactile and visual tasks
The 3 experiments
Visual investigations
Tactile investigations
Right hemisphere tests
What type of study is this and why?
A quasi experiment because the independent variable, whether the participant was split brained or not, was naturally occurring
Independent variable
Whether participants were split brained or not
Dependent variable
The responses participants had to the tactile and visual tasks given
Experimental design
Independent measures: 2 categories of split brain compared to not split brain
We cannot manipulate this to be repeated measures
Sample size
11 split brain patients
9 recently undergone surgery
2 had it years before
Sample method
Opportunity
The apparatus name
Tachiotoscope
The set up 💯
Image back projected onto a screen the participant would look at
With a spot in the middle
Tactile objects behind screen out of view
Participants were told to…
Focus on the spot in the middle
When an image is presented to either side of the dot
Then the opposite hemisphere will internalise it and can perform actions based on its function
Field of view meaning
Either the eight side of the vision or left side
This is independent of left/right eyeballs: left field of view foes to right hemisphere and vice versa
Why project the image for 1/10 of a second?
To prevent eyes from moving to the image, we want to project the image to either enter the right or left field of view
We don’t want it to be the focus thus have it enter both hemispheres
How can we ensure that the information doesn’t enter both hemispheres?
Have participants sit in silence, information not sent to hemisphere by outwards speech
Have participant hide hands, only opposite hemisphere can control this hand so information not transferred by visually seeing the hands
In the visual investigations, when the image of key is shown to the right visual field what happens?
Information goes to left hemisphere which controls the language
So participant can say what they see, ‘key’