Due to the exclusivity of the hemispheres in split-brain patients, they are able to clearly demonstrate the different roles of each hemisphere. When split-brain patients are shown a word in the left field of their vision ("key"), it is projected to the right hemisphere of their brain. The right hemisphere of the brain controls the left hand, and thus, the left hand is able to pick up the key using this information. However, a split-brain patient cannot verbalize what he or she has picked up because the language center of the brain lies in the left hemisphere. Because of this, only that which appears in the right field of vision ("ring") and thus is projected into the left hemisphere of the brain can be verbalized.
The hemispheres of the brain are unequal in their ability to handle certain tasks; this is referred to as hemispheric specialization. For example, the left hemisphere of the brain is more dominant at performing verbal tasks, versus the right hemisphere which is good at spatial tasks. The corpus callosum allows these two halves to communicate with each other and exchange vital information.
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