MadSci Network: NeuroScience
Query:

Re: How can you tell which side of the brain you use the most?

Area: NeuroScience
Posted By: Salvatore Cullari, Professor and Chair,Lebanon Valley College
Date: Mon Mar 17 15:06:52 1997
Message:

The human brain is a truly amazing product of nature. Its average weight is about three pounds and it contains about 100 billion neurons. The brain is made up of a left and right hemisphere, which are connected by the corpus callosum. Although these two sections appear to be mirror images of each other, in reality they are not. Further, there seem to be hemispheric differences between men an women.

The relationship between these two hemispheres and our bodies is that the left side of our brain (generally) controls the right side of our body and the right side of our brain controls the left side of our body. This is called contra-lateral control. In most right handed individuals, the left hemisphere is responsible for speech production and language recognition. Although the right side of our brain does have some linguistic abilities, people who have a stroke in the left side of their brain near what is called Broca's area, usually develop aphasia, which is an inability to express oneself verbally or in writing. The left side of our brain also appears to control other "linear thinking" tasks such as reading and arithmetic. In summary, the left side of our brain seems to use a temporal and sequential processing style.

On the other hand, the right side of our brain appears to be more efficient in processing and recognizing patterns. It tends to use a simultaneous processing style. For example, this is the style we use to interpret a portrait of someone. Humans appear to have right hemisphere specialization for visual, tactile and musical patterns. There is also some speculation that the right side of our brain controls emotions and creativity, but this is a very simplistic assumption.

Something very interesting happens if we totally disconnect the left and right hemispheres by cutting through the corpus collasum. This sometimes done to treat drug resistant epilepsy. Roger Sperry (who won a Nobel prize in 1981) and Michael Gazzaniga did pioneering research with these so-called split-brain individuals. What they found was that if you hold a common object in their left visual field (which is projected on the right side of the brain), they could not verbally identify it. However, if the object was projected in their right visual field (projecting it on the left side of the brain), they had no difficulty saying what it was. Apparently, our two hemispheres communicate with each other through the corpus collasum, and when it is severed, the two parts of our brains appear to operate independently.

In terms of answering the question of which side of the brain you use most, it really depends on the task. As far as I know, we do not have any practical tests that directly show which part of our brain we tend to use the most. However, there is some interesting research conducted by a man named Paivio which might shed some light on this matter. According to Paivio's dual coding theory, individuals differ in imaginal and verbal associative preferences and abilities. In other words, some people like to process information verbally (suggesting left brain utilization) and others do so through imagery (suggesting right brain use). He actually developed a scale called the Individual Differences Questionnaire to assess these differences. Paivio describes this test in his book, Mental representations: A dual coding approach. You might also be interested in reading, Teaching for the two-sided mind, by Linda Verlee Williams.


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