You've probably heard of "left-brained" people and "right-brained people" and wondered what the descriptions mean. These terms refer to a person's tendency to predominantly use one hemisphere (side) of the brain rather than the other. Because the left hemisphere and right hemisphere specialize in certain abilities, having those abilities demonstrates which of your hemispheres is dominant. While the idea of hemisphere specialization is not as black and white as some promoters make it out to be, it can provide an interesting way to analyze your mental strengths and weaknesses. If you think you might be "left-brained," see how you match up with these left side brain functions.
Numerous cognitive psychologists, such as M.J. Farah and M. S. Gazzaniga, have demonstrated that language abilities are localized in the left hemisphere. These scientists conducted studies on split brain patients who had had the connection between their two hemispheres cut so that the two brain sides could not communicate with each other. In one study, the researchers flashed the word "pencil" to the right side of the patients' vision. They found out that the patients could pick out a pencil from choices with their left hand, which the right side of the brain controls, but could not say the word "pencil." This indicated that the left side of the brain controls language, although the skill is more equally divided between sides in left-handed people. The right side of the brain understands meanings, but cannot put together words or sentences following the rules of grammar the way that the left side can.
The left side of the brain also plays a crucial role in movement. In 1999, Gazzinger discovered that people suffering from apraxia often have damage to their left brain hemispheres. Because apraxia is an inability to perform familiar purposeful movements, he was able to conclude that the left hemisphere and movement are related. This might be why those people with left brain dominance tend to excel at activities like dance and athletics.
In her book, "Mapping the Mind," science writer Rita Carter discusses yet another study highlighting left side brain functions. In this case, a person with damage to the left side of the brain was asked to copy a diagram. The person drew a general outline but could not fill in the details. Those with damage to the right side of the brain had opposite results--they drew details but did not get the outline correct. Functional brain imaging like EEG and PET scans also suggest that processing details is a left side brain function. Hence, if you are "left-brained," you probably do well with detailed-oriented tasks such as balancing a checkbook.
If the left side of your brain is dominant, you might also be good at analytical processing. Cognitive psychologist J. Levy conducted a study in 1974 and found some evidence that the left hemisphere goes through information piece-by-piece while the right hemisphere processes information in a "big picture" fashion. However, other psychologists like Gazzaniga have questioned whether Levy's results can be interpreted this way, and analytical ability is one of the more questioned specializations of the left hemisphere.
Gazzaniga calls the left hemisphere "the interpreter." This is because you are more likely to use the left side of your brain when explaining an event or telling a story. The left side of the brain gives coherence and logic to the pictures, feelings and intuitions of the right side of the brain.