Currently, there is a tremendous amount of interest, among scientists and educators, in how each brain hemisphere processes information, how information is shared between the brain hemispheres, and how the two hemispheres work together to process information.
This pioneering work was conducted by neuropsychologist Roger Sperry and his associates at Caltech in the 1960s.
However, it was in 1940 that two articles appeared dealing with the corpus coliseum, a huge band of nerve fibers, that relay information between the two brain hemispheres:
1. An article by T. C. Erickson describes how an epileptic discharge of activity spread from one hemisphere to the other via the corpus coliseum in the brains of monkeys (Erickson).
2. An article by Van Wagenen and Herren describes how damage to the corpus coliseum often reduced the number of seizures experienced by human epileptics (Wagenen, et al.).
These two studies led to a radical treatment for humans with epilepsy who did not respond to traditional treatments. This new treatment, involving severing the corpus coliseum, was termed “split-brain surgery” (corpus callosotomy).
Let’s look at the research.
Sperry’s split-brain experiments
Sperry and his associates had done a great deal of experimental work with cats that had the optic chiasm severed. In a normal cat or human, information from each eye goes to both brain hemispheres. By severing the optic chiasm, the information from each eye goes only to the ipsilateral or same side hemisphere. That is, information from the left eye goes only to the left hemisphere, and information from the right eye goes only to the right hemisphere.
Sperry showed that, when information goes to only one hemisphere in a cat with the corpus coliseum split, the information is not available to the other hemisphere. Sperry was the first to investigate the effects of split-brain surgery on human epileptics.
“Each left and right hemisphere has its own private chain of memories and learning experiences that are inaccessible to recall by the other hemisphere. In many respects, each disconnected hemisphere appears to have a separate mind of its own.” R. W. Sperry
One experiment that is representative of Sperry’s work is described as follows:
1. A split-brain patient is seated in front of a screen and is asked to look directly at a black dot in the center of the screen. A picture of a cup is flashed briefly to the right of the dot. This information is lateralized, or delivered only, to her left hemisphere. The subject is asked what she saw. Since the information went to the left hemisphere or speaking hemisphere, the subject answers “cup”.
2. A picture of a fork is then flashed to the left of the dot. This information is lateralized to the right or non-speaking hemisphere. When the subject is asked what she saw, she says “nothing”, since the right hemisphere cannot produce language. However, if she is asked to reach under the screen with her left hand (controlled by the right hemisphere) and pick out the object she saw from several hidden objects, she is able to do this. If she is then asked to name the object that she has picked out, she cannot verbalize the response (Sperry).
Experiments such as these led Sperry to suggest that “each disconnected hemisphere appears to have a mind of its own”.
It appears that, at least in a split-brain subject, each hemisphere has no knowledge of information processed solely by the opposite hemisphere.
Here’s a YouTube video of the experiment.
Hampden-Turner’s maps of the mind
In the wake of Sperry’s findings, many experiments were conducted on both split-brain and normal humans.
In 1981, Hampden-Turner summarized much of the research as suggesting that the left hemisphere is better at verbal, analytic, sequential, reductive-into-parts, and time-oriented tasks, while the right hemisphere is better at non-verbal, holistic, synthetic, visuospatial, intuitive, and timeless tasks.
Consequently, this led many people to try to become more “left-brain” or “right-brain”.
It is important to note that virtually all of the left/right hemisphere distinctions have resulted from experiments where stimuli are delivered to only one hemisphere.
Hellige’s interhemispheric interaction
Joseph Hellige, in 1987, pointed out that, when humans interacted with their environment, both brain hemispheres received the same information and, often, both hemispheres were capable of processing the information. The important question facing experimental psychologists now is, to what extent do the brain hemispheres interact to process the information received.
Hellige then conducted a study exploring this very question. By using an instrument called a tachistoscope, stimuli were either delivered to each hemisphere individually or to both hemispheres simultaneously. The research question was whether the bilateral condition (where the stimuli were delivered to both hemispheres) would produce results like the left hemisphere in isolation, the right hemisphere in isolation, or a combination of the two.
The results showed that, when the information was delivered to both brain hemispheres simultaneously, the resulting performance appeared to be a combination of input from both hemispheres, with the extent to which each hemisphere contributed to overall performance varying greatly between subjects. That is, each subject appeared to have his or her own style of processing rather than simply relying solely on the left or right hemispheric style of processing.
Use both brain hemispheres
The above study is one of the first to investigate how the brain hemispheres work together. It is representative of the current interest in whole-brain processing.
As indicated, there is no general rule concerning processing style. Rather, people will vary in how much they use each hemisphere. However, the results are clear in that, as stressed by a great many brain researchers, the hemispheres do not act independently and there appears to be a great deal of sharing between the hemispheres during analytical thinking or problem-solving.
You may apply this information in your business in a variety of ways:
1. You may want people with very different problem-solving styles working together on tasks. Since input from each person may be radically different from the other person, a new kind of synthesis may develop.
2. You may want young people with less business experience but more recent school knowledge working with older mentors who have been in the field for a number of years. Each can contribute a different view on the current tasks and can stimulate creative ways of dealing with the problems at hand.
Another key point is the power of daydreaming.
This issue of the importance of daydreaming and night-dreaming on human behavior has been a controversial one for many years. Recently animal experiments have provided evidence that suggests that, indeed, dreaming, whether daydreaming or during the night sleep cycle, may have a tremendous impact on human performance.
Michael Gazzaniga, in his book Mind Matters, cites evidence relating the importance of rapid eye movement or REM (a state the human is in while dreaming) to learning in animals.
In one study, rats were trained to perform a particular task. While they were learning the task during the waking hours, the time they spent in REM during their sleep cycles increased. Once the task had been mastered, their REM time returned to normal levels.
More importantly, if they were deprived of REM or dreaming, by being awakened, their performance on the task was impaired. In other words, they performed poorly on the task if they were not allowed to dream during their sleep cycles. These results provided evidence for the importance of dreaming on learning a new task.
Take breaks at work
You may benefit from this finding to help you learn and perform better, both in your personal and professional life. These results suggest that, after a training, study, or brainstorming period, it may be extremely rewarding to not only take a break but take a break in which you rest and let your mind go blank.
It is imperative that you do not become occupied with another task, for this may clutter the mind and interfere with learning. In addition, it is advisable to review new information before going to bed.
If one may generalize from the animal studies to humans, a process which is done quite often in research, the amount of time you spend dreaming following learning new information or a new task can increase your comprehension and performance.
- Erickson, T. C. “Spread of epileptic discharge.” Archives of Neurology and Psychiatry. 1940, vol 43, pp 429-452.
- Gazzaniga, M. Mind Matters. Houghton Mifflin Company, Boston, 1988.
- Hellige, J. “Interhemispheric Interaction: Models, Paradigms and Recent Findings.” In Duality and Unity of the Brain: Unified Functioning and Specialization of the Hemispheres. Macmillan Press Ltd, London, 1987.
- Sperry R. W. “Hemispheric Disconnection and Unity in Conscious Awareness.” Scientific American, 1968 vol 23, pp 723-733.
- Turner, C. Maps of the Mind. Collier Books, New York, 1981.
- Van Wagenen, W. & Herren, R. “Surgical Division of Commissural Pathways in the Corpus Callosum.” Archives of Neurology and Psychiatry, 1940, vol 44, pp 740-759.