Michael Gazzaniga Helena Yeung and Brian Zhao
Background <ul><li>Born on December 12, 1939 </li></ul><ul><li>Graduated from Dartmouth College in 1961, received his Ph.D...
Findings  (split hemispheres) <ul><li>1967 </li></ul><ul><ul><li>Experiment on split-brain patients </li></ul></ul><ul><li...
Findings  (nonverbal right hemisphere) <ul><li>1967 </li></ul><ul><ul><li>Experiment in split-brain patients </li></ul></u...
Findings  (isolated hemispheres) <ul><li>Case study: WJ (epileptic patient with split-brain) </li></ul><ul><ul><li>Held ap...
Findings  (the interpreter) <ul><li>Gazzaniga labeled the left hemisphere as “the brain’s interpreter” (1998) </li></ul><u...
Findings (the “gist” capacity) <ul><li>Experiment: participants were asked to bet on which of two events would occur, one ...
Findings (right hemisphere) <ul><li>Perceptual grouping: </li></ul><ul><ul><li>You know that a specific object is at the b...
Methodology <ul><li>Experiments: Performed on patients who had undergone split-brain procedures </li></ul><ul><ul><li>Stud...
Evaluation (findings) <ul><li>Strengths: </li></ul><ul><ul><li>Supports concept of lateralization in the brain </li></ul><...
Methodology <ul><li>Strengths: </li></ul><ul><ul><li>Experimented on a large population of split-brain patients </li></ul>...
Works Cited <ul><li>Myers, D. G. (2007).  Psychology . New York, NY: Worth Publishers.  </li></ul><ul><li>http://www.abc.n...
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Michael Gazzaniga

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Michael Gazzaniga

  1. 1. Michael Gazzaniga Helena Yeung and Brian Zhao
  2. 2. Background <ul><li>Born on December 12, 1939 </li></ul><ul><li>Graduated from Dartmouth College in 1961, received his Ph.D at Cal Tech in 1964 </li></ul><ul><li>Worked under Sperry as a his protégé </li></ul><ul><ul><li>Sperry was a pioneer of human split-brain research </li></ul></ul><ul><li>Theories regarding functional lateralism in the brain had already been established </li></ul>
  3. 3. Findings (split hemispheres) <ul><li>1967 </li></ul><ul><ul><li>Experiment on split-brain patients </li></ul></ul><ul><li>Concluded that split-brain patients possessed two hemispheres that acted independently </li></ul>
  4. 4. Findings (nonverbal right hemisphere) <ul><li>1967 </li></ul><ul><ul><li>Experiment in split-brain patients </li></ul></ul><ul><ul><li>Flashed a picture of spoon to participant’s right hemisphere </li></ul></ul><ul><ul><ul><li>Asked participant to identify the object: participants generally replied with “I don’t know.” </li></ul></ul></ul><ul><ul><ul><li>Asked participant to choose the object from a pile of objects: participants would generally choose correctly. </li></ul></ul></ul><ul><li>Concluded that the right hemisphere in split-brain patients was “nonverbal” </li></ul>
  5. 5. Findings (isolated hemispheres) <ul><li>Case study: WJ (epileptic patient with split-brain) </li></ul><ul><ul><li>Held apple to WJ’s right eye, and WJ would say, “I see an apple” </li></ul></ul><ul><ul><li>Held apple to WJ’s left eye, and WJ would say, “I don’t see anything,” but would be able to pick out a pictorial representation w/ left hand </li></ul></ul><ul><li>Concluded that two hemispheres of the split brain do not communicate with each other </li></ul>
  6. 6. Findings (the interpreter) <ul><li>Gazzaniga labeled the left hemisphere as “the brain’s interpreter” (1998) </li></ul><ul><ul><li>Researchers noticed that, when information is sent to the right-hemisphere to control the left hand, the left hemisphere, when it sees this, interprets this event, and consolidates it with its “ongoing mental monologue” </li></ul></ul><ul><ul><li>Gazzaniga proposed that the left hemisphere rationalizes the actions, protecting the holistic nature of the individual’s mind, giving the individual a sense of self </li></ul></ul>
  7. 7. Findings (the “gist” capacity) <ul><li>Experiment: participants were asked to bet on which of two events would occur, one having an 80% chance of occurring, and the other having a 20% chance of occurring. </li></ul><ul><ul><li>Instead of choosing the event that repeatedly occurred, humans often attempted to discern patterns within the frequency of the events </li></ul></ul><ul><ul><li>A rat would lose less money than a human through the same process, as they rely more on the right hemisphere </li></ul></ul><ul><li>Concluded that right brain takes events and images at face value, while the left brain made theories. </li></ul>
  8. 8. Findings (right hemisphere) <ul><li>Perceptual grouping: </li></ul><ul><ul><li>You know that a specific object is at the bottom of a pile, and you go directly for it, without searching </li></ul></ul><ul><ul><li>You see a deer in the woods; you can only see parts of the deer, but your brain mentally puts the missing pieces together </li></ul></ul>
  9. 9. Methodology <ul><li>Experiments: Performed on patients who had undergone split-brain procedures </li></ul><ul><ul><li>Studied with an apparatus that took advantage of separate visual fields </li></ul></ul><ul><ul><ul><li>If a split-brain patient is seated in front of a screen and told to look at an “X” in the middle of the screen, and if the picture is flashed on the screen too quickly for an eye movement to occur, then everything to the left of the X will go to the right hemisphere. Everything to the right of the X will go to the left hemisphere </li></ul></ul></ul><ul><ul><li>Displayed HE*ART on a screen, asked participants to stare at dot </li></ul></ul><ul><ul><ul><li>When asked what word they saw, participants generally replied with “ART” </li></ul></ul></ul><ul><ul><ul><li>When asked to identify the word with their left finger, participants pointed at “HE” </li></ul></ul></ul><ul><li>Case study: WJ (split-brain patient) </li></ul>
  10. 10. Evaluation (findings) <ul><li>Strengths: </li></ul><ul><ul><li>Supports concept of lateralization in the brain </li></ul></ul><ul><ul><ul><li>Provides details regarding the lateralized nature of each hemisphere </li></ul></ul></ul><ul><ul><ul><ul><li>Left hemisphere is the “interpreter,” while right hemisphere deals with perceptual grouping </li></ul></ul></ul></ul><ul><li>Weaknesses: </li></ul><ul><ul><li>Not necessarily applicable to all humans, as experimentation was done on split-brain patients </li></ul></ul><ul><ul><ul><li>Split-brain is not a naturally occurring affliction </li></ul></ul></ul><ul><ul><li>America-centered; cultural biases are not taken into consideration (eg. For language processing in Chinese speakers) </li></ul></ul>
  11. 11. Methodology <ul><li>Strengths: </li></ul><ul><ul><li>Experimented on a large population of split-brain patients </li></ul></ul><ul><ul><li>Tested both sides of the brain; did not assume control between the hemispheres </li></ul></ul><ul><li>Limitations: </li></ul><ul><ul><li>Used case studies (WJ) that aren’t necessarily applicable to everyone </li></ul></ul><ul><ul><li>Extraneous variables not considered (culture, gender, handedness) </li></ul></ul>
  12. 12. Works Cited <ul><li>Myers, D. G. (2007). Psychology . New York, NY: Worth Publishers. </li></ul><ul><li>http://www.abc.net.au/rn/allinthemind/stories/2008/2276587.htm </li></ul><ul><li>http://www.downstreamer.com/mindspast.html </li></ul><ul><li>http://www.psywww.com/intropsych/ch02_human_nervous_system/dual_consciousness_in_split-brain.html </li></ul>

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