Split Brain research Flashcards
How does the ‘normal vision’ system work?
Normal vision - everything you see in left visual field is sent to the right hemisphere, and everything you see in your right visual field is sent to the left hemisphere.
What is information shared via, for the two cerebral hemispheres?
Via the corpus collosum that connects the two
Which two psychologists studied patients who had been treated for epilepsy by cutting their corpus callosum’s ?
Roger Sperry and Michael Gazzaniga
What did Roger Sherry and Michael Gazzaniga do (1967) test?
Studied patients who had been treated for epilepsy by cutting their corpus callosums.
What was the older treatment for epilepsy?
Cutting the corpus callosum when drugs available weren’t as effective as they are now
What is the corpus callosum made of?
A bundle of neurons connecting the two hemispheres, and axons that connect these neurons.
Why did Sperry + Mazzaniga choose their epilepsy patients and what did cutting the corpus callosum prevent?
They chose them in 1960s/70s as each hemisphere of brain no longer communicated with the other.
Cutting the CC meant the epilepsy wouldn’t spread hemispherically.
What was the method to Sperry + Mazzaniga’s original study?
-Asked patients to focus on a fixation point
-Presented words to each of their visual field, therefore to each hemisphere.
What were two results from Sperry + Mazzaniga’s original study? (regarding RVF, LVF)
-Found that if presented words to the RVF, the patients could report all of them as the info went to the left hemisphere where spoken language occurs
-However, if they presented words to the LVF the information went to right hemisphere, that doesn’t have spoken language, meaning they couldn’t say the word they saw.
Despite not being able to say the word when it was presented to their LVF, what could they do instead?
They could draw a picture of the word with their left hand, which is controlled by the right hemisphere.
The patient could then look at the picture with RVF and the left hemisphere could say what word they originally saw.
What does the research from Sperry and Mazzaniga’s original study support?
Concept of lateralisation of functions, as spoken language was only available in the left hemisphere.
What was the second study that Gazzaniga conducted? (method)
-Gazzaniga presented a split-brain patient with pictures of faces, painted made of fruits by Artist, Arcimboldo.
What did previous research suggest regarding Mazzaniga’s second study?
Suggested that facial recognition occurs in the right hemisphere– if this ability was in right hemisphere, then split-brain patients should only recall faces in LVF.
What did Gazzaniga find from his second study and what do the findings support?
Found that in the LVF, images could be recognised as faces, but in RVF they were seen as parts, not faces.
Supports idea of lateralisation + that face procession takes place in right hemisphere.
Explain the variation that Gazzaniga ran, regarding VFs?
He asked ppts to identify something in their LVF and so processed in their right hemisphere, they then chose the correct object with their left hand from a bag containing several objects.
What are the 2 strengths to Split-Brain research?
PPTs could answer for the correct object with a high degree of accuracy
The research has been very useful in helping to show functions that are found in each hemisphere, supporting the concept of lateralisation of function.
What does the variation that Gazzaniga ran suggest about spoken language in the hemispheres?
Supports that the right hemisphere hasn’t got any spoken language, and that there must be unspoken language instead, that could connect a written word to the correct shape.
Explain the issue of Generalisability with Split-brain research.
It’s difficult to generalise to a wider population as only 11 ppts partook in the original study. This is even more truer as all ppts received brain surgery for severe epilepsy, therefore representing a minority to the majority of healthy-brained people.
What was the criticism of Split-Brain research raised by Andrewes (2001) ?
States many split-brain studies are published with as few as 3 ppts, meaning drawing any nomothetic conclusions is very difficult, and perhaps shouldn’t be done.
Explain the issue with Split-brain research regarding recent treatments?
Treatments for epilepsy have improved. i.e drugs, and surgery doesn’t occur anymore, meaning, the patients are quite old, this means they aren’t representative of the general population.
What did Gazzaniga (1998) criticise against his own study? Provide an example of what the researchers Turk et al. (2002) found.
He suggested some of his earlier discoveries are wrong, e.g some ppts have been shown to develop conscious language abilities in both hemispheres.
Turk et al. (2002) reported on J.W, a ppt who can now speak consciously from the right hemisphere too.
What is the issue with Split-Brain research that regards validity?
It lacks ecological validity due to the research being conducted in the lab under artificial experimental conditions.
What are the three functions that were found lateralised and in which hemisphere were they lateralised from Split-Brain studies?
Language is in both hemispheres, but only spoken language is in the Left Hemisphere
Face procession is in Right Hemisphere
Logical decision making is in Left Hemisphere
What is Alien Hand Syndrome?
It is is a rare syndrome linked to the severing of the corpus callosum.
It involves involuntary left-handed movements, controlled by the right hemisphere.
