Lateralization of function in the cerebral hemispheres One of the main goals of neuroscience is to be able to understand the relationships between the structures of the nervous system and a person's external behavior. It is often difficult or unethical to directly study the nervous system during a behavior and it is necessary to use indirect methods instead. An example of such an indirect method is using the subject's preferred hand to predict which of the two cerebral hemispheres is dominant. There are some difficulties with his method of studying lateralization of function, but if it could be better understood it could have many practical and theoretical implications for the study of neuroscience. The cerebral hemispheres are very similar in appearance, but differ significantly in their structure. One of the best-known differences between the two structures is motor control; the right hemisphere controls the left half of the body and the left hemisphere controls the right half of the body. These differences in motor control were discovered primarily through examining paralysis caused by stroke or other damage to a specific hemisphere. In 1861 the theory of lateralization of function was expanded with Paul Broca's discovery of the structure in the right hemisphere that controlled language, this structure is now known as Broca's area. Like many other advances in neuroscience, this discovery was made possible by an unfortunate stroke victim, who in this case lost the ability to speak. After his death Broca examined his brain and discovered damage to the right hemisphere at this now famous location. This discovery was followed soon after by the discovery of an area, again in the right hemisphere, responsible for understanding the written word. This area became known as Wernicke's area after the man who discovered it by "studying patients with certain comprehension deficits" (1) and comparing these deficits to brain damage. These two discoveries created a watershed in experimentation as other scientists attempted to uncover more functional differences between the hemispheres. This body of research has created a very stereotypical understanding of the two hemispheres. The left hemisphere is known as the language hemisphere. It is also believed to control general cognitive functions. Some researchers have gone so far as to attribute consciousness to the left hemisphere. The right hemisphere is assigned nonverbal processes such as special relationships and the detection of complicated auditory tones .