The figure is somewhat lower for left handers, approximately 70%" (Hemisphere specialization, 2010, Macalester University).
The fact that some people's right hemispheres do possess the ability to 'speak' enabled further illuminating results to be generated by studying split brain patients: in the case of one split brain operation patient 'Paul,' for example, Paul's right hemisphere was able to express itself alone: "Paul's right hemisphere stated that he wanted to be an automobile racer while his left hemisphere wanted to be a draftsman" (Behavior, 2010, Macalester University). It was as if Paul's different hemispheres had different personalities, even different political opinions. The left side of the brain controls the right side of the individual's body and the right side controls the left hand. Paul wrote with his right-dominated left hand that he wanted to be a presumably exciting occupation -- and that he hated Richard Nixon. The left side, using the right hand said he would prefer a more practical occupation, and expressed a more balanced view of Nixon.
Not all patients' right sides were as verbal as Paul's, and some patients merely experienced difficulty in emotional expressiveness. Other accounts of post-surgery behavior were extremely disturbing in terms of patient's development of split identities. One patient "would sometimes find himself pulling his pants down with one hand and pulling them up with the other. Once, he grabbed his wife with his left hand and shook her violently, with the right hand trying to come to his wife's aid in bringing the left belligerent hand under control. Once, while I [the patient's doctor] was playing horseshoes with the patient in his backyard, he happened to pick up an ax with his left hand. Because it was entirely likely that the more aggressive right hemisphere might be in control, I discretely left the scene-not wanting to be the victim for the test case of which half-brain does society punish or execute," said the doctor who performed the procedure (Dewey 2010).
Sperry received the Nobel Prize for developing the split-brain operation, although for his epileptic patients the operations proved to be a mixed blessing (Dewey 2010). Since the 1950s, when split brain experiments were...
A new form of surgery, devised by P.J. Vogel only "severs a pipe-cleaner-sized cross connection known as the anterior commissure. But the back of the corpus callosum -- the splenium -- he [Vogel] leaves intact" (New developments, 2010, Macalester University). This is good news for individuals suffering from severe epilepsy, given the severity of the unintended consequences of the more radical operation. Still, what was learned from the early patients was valuable, and has been helpful in assisting scientists in understanding human consciousness and helping rehabilitate individuals after traumatic brain injuries.
References
Behavior of split brain patients. (2010). Macalester University. Retrieved April 5,
2010 at http://www.macalester.edu/psychology/whathap/ubnrp/Split_Brain/Behavior.html
A brief history of split brain experiments. (2010). Macalester University. Retrieved April 5,
2010 at http://www.macalester.edu/psychology/whathap/ubnrp/Split_Brain/Pioneers.html
Dewey, Russ. (2010). The split brain operation Chapter 2: The human nervous system.
Psychology: An introduction. Excerpted April 5, 2010 at http://www.psywww.com/intropsych/ch02_human_nervous_system/split-brain_operation.html
Hemisphere specialization. (2010). Macalester University. Retrieved April 5,
2010 at http://www.macalester.edu/psychology/whathap/ubnrp/Split_Brain/Hemispheric_Specialization.html
New developments in split brain surgery. (2010). Macalester University. Retrieved April 5, 2010
at http://www.macalester.edu/psychology/whathap/ubnrp/Split_Brain/Current.html
Palmer, Jerry. (2003, February 2). Split-brain surgery and its effects on behavior. Eastern Kentucky University. Retrieved April 5, 2010 at http://people.eku.edu/palmerj/200/split.htm
Split brain consciousness. (2010). Macalester University. Retrieved April 5, 2010 at http://www.macalester.edu/psychology/whathap/ubnrp/Split_Brain/Split_Brain_Consciousness.html
