by Zeev Nitsan
The right hemisphere resembles a weariless cartographer who is constantly busy “sketching” new brain maps, while the left hemisphere serves as the archive of maps that have already been validated and found suitable for navigating the paths of life.
The right hemisphere and the left hemisphere can be referred to as “the Magellan hemisphere” and the “there-is-no-place-like-home hemisphere” accordingly. The right hemisphere is the one that processes the new and the unfamiliar. It pursues the different and the exotic, and its horizons wish to reach beyond the present horizon of thought. The Portuguese seaman Ferdinand Magellan, who circled the world, summarizes central components of its nature. On the other hand, the left hemisphere groups a cluster of insights for coping with situations in which we have gained experience, and it usually channels our consciousness toward the familiar and routine. A possible motto for it is “there is no place like home.”
There is a dynamic balance between the innovative insights, which the right hemisphere tends to create, and the conservative insights, which the left hemisphere tends to hoard.
The conservatism of the left intends to protect our knowledge of the world, but it sometimes compromises the update of this knowledge.
Language and the Hemispheres
The surface of reality is covered in a fog of uncertainty. Words resemble a retreat toward certainty—conceptualization of terms we became familiar with through our experiences in the world.
Words are also capable of creating reality; this is one of the common interpretations of the magical decree “abra kadabra” - in ancient Aramaic “abra kedabra” which is: “let it create as I say”. Word as working magic that create reality by mere words.
The main, though not exclusive, impresario of the words’ show is the left hemisphere, which is the residence of the familiar. However, the saying of the seventeenth-century French neurologist Paul Broca, who said that man speaks through the left hemisphere, is only partially true.
The assumption regarding total hegemony of the left hemisphere over language has been cracked recently.
New findings refute the supposition regarding verbal blindness of the right hemisphere. It turns out that innovative creatures of language, such as metaphors, multiple-meaning words, puns, and layers of meaning, are first processed in the right hemisphere. Moreover, the right hemisphere has an important role in understanding poetry, which is full of innovative idioms that can be linguistically challenging.
It also seems that language acquisition during childhood follows a rule, according to which new verbal information tends to be processed by the right hemisphere. Since the sounds and words of language are new to a child’s brain, the main entrance of language into the halls of the brain is through the right side. On the other hand, once language is acquired, its repertoire of familiar terms is, in fact, a collection of generic patterns that tends to be hoarded, like any other type of familiar information, within the left hemisphere.
The traditional view regarding hemispheric function, which ascribed all language functions to the left hemisphere, is inaccurate, to say the least, and some might even play a requiem for it.
Shoals at the Left Bank of the River of Language
The incidence of dyslexia (a disorder related to reading development among children) among left-handed people is significantly higher than among right-handed people. It might reflect damage to the left hemisphere during early stages of development, which led to selecting the left hand as the dominant hand. The hemisphere that controls the movement of the hand is located opposite side to it, since movement control pathways are crossed.
“Aphasia” (language-function impairment) is also mostly caused as a result of damage to the function of the left hemisphere. The rare condition called “hyperphasia,” however, characterized by a tendency to be overtalkative and mechanically pronounce long successions of words, is mostly detected among people who suffer from a rare brain syndrome that is named after Williams and is related to a left hemisphere that is bigger than normal.
It was found that women have greater brain flexibility with respect to preserving language functions, which is also reflected in higher compensation ability at times of injury to the main language areas in the brain. Among women who suffer from damage to the left hemisphere, language functions are usually impaired less severely than those of men who suffer similar damage.
“Morphing” is a term that describes a merger of two distinguished, separate patterns into a single pattern that preserves the characteristics of the two patterns. An experiment that included the use of morphing showed findings that might confirm the hemispheric expertise hypothesis. During the experiment, a gradual merging of the face of the participant with the face of Marilyn Monroe was conducted on a sequence of chimeric portraits on a computer screen. The profiles’ contribution to the common portrait varied. Afterward, a supervised, selective anesthesia of the right hemisphere in the patient’s brain was performed by injecting short-term anesthetic (sodium amytal) to the right carotid artery, and, as a result, the left hemisphere was entrusted with the processing of visual information. When the new portrait was presented to her, the patient failed to identify her own face within the merged portrait but succeeded in identifying the familiar features of Marilyn Monroe. On the other hand, when the left hemisphere was put under anesthesia, and the wand of visual information processing was transferred to the right hemisphere, the patient identified her own features as well as the features of Marilyn Monroe. Possible interpretation that is compatible with the “familiar and unfamiliar” hypothesis is that it seems that Marilyn Monroe’s features constitute familiar knowledge, and our own face, when merged with the features of another human being, constitutes a novelty that requires the involvement of the right hemisphere.
Gender Differences in the Brain-Activation Profile
Although this hypothesis constitutes a generalization, which naturally involves faults, and there is no dispute over the fact that any person, man or woman, in our world is unique, particularly as a result of the uniqueness of their brain, some claim, as an educated guess, that in an average male brain certain behavioral patterns will be more prominent. These patterns are usually ascribed to the right hemisphere—for example, the pursuit of novelties, daring, and the urge to wander. According to this supposition, behavioral patterns deriving from the right amygdala, which mediates urges and impulsive reactions in a more prominent manner, will be found in a male’s brain. This hypothesis is controversial, and its evidence base does not suffice in order to see it as an “irrefutable truth.”
The Similar and the Different
The reciprocal relations between the two hemispheres—the right, as the one that distinguishes, stresses the different and the new; and the left, as the one that finds similarities to the familiar, includes and tilts toward the drainage basins of familiar insights—are, according to common hypotheses, at the basis of our cognitive products.
Generalization and uniqueness refer to humans, as well. Although all human beings are made according to a similar physiological format, which also leads to a similar psychological format and to numerous similarities in terms of cognitive processes, on the other hand, each person creates a unique emotional and cognitive climate in the planet of his skull, which constitutes a unique ecological niche.
Some might claim that the mix of the right style, which is about finding the difference, and the left style, which is more about detecting the similar, is evident not only with respect to “passive perception of stimulation”—a reflection of the world of phenomena by the sensory organs—but also with respect to producing original thoughts, which are born in our inner world.
Sayings that resemble Koheleth’s saying “There is nothing new under the sun” can be seen as reflecting the insight of the left hemisphere; the words were probably said by Koheleth at an old age, at a time when, through the lenses of the left hemisphere, many things seem as variations on the same theme.
The spiritual heritage of
Charles Darwin, who was responsible for one of the most shaking revolutions of thought in human history, might serve as an example of the advantages that are part of seeing the similar—i.e., by looking through the left hemisphere’s lens.
For years, naturalists have been busy with finding more and more species of animals and plants while emphasizing the difference between them. Semiology became very popular when more and more species and subspecies were added and marked according to the slight differences between them. Right-hemisphere-oriented thinking ruled. On the other hand, Darwin noticed the similar, the similarities between the various forms, which was the source of his insight regarding the organizing principle of the development of life. We might say that Darwin’s right hemisphere, the explorer of the unknown, was responsible for his decision to set sail on the Beagle for the other part of the world and spend five years on board. In the process of consolidating his insights throughout the years, however, it is the left hemisphere that seems to have had the upper hand. His insight ranged from one end, of the uniqueness of details, to the end of “common ground.”
Darwin published his book On the Origin of Species at a relatively old age, perhaps as a reflection of the left hemisphere approach that matured in him.
A broom—is it a device for moving dust or for moving witches? An interesting assumption is that creativity is enabled due to the availability of structural infrastructure that is prone to plasticity and the creation of new neural networking, which encodes new information, probably mostly in the right hemisphere. The left hemisphere tends to connect new concepts in a concrete “earthy” manner and usually does not sail to the remote lands of imagination. It seems that it is prone to less flexibility with regard to structural infrastructure that encodes information. The left hemisphere is likely to relate to a broom as a “device for moving dust” from one place to another, whereas the right hemisphere is likely to relate to it as a “device for moving witches from one place to another.”
Age-Dependent Changes at the Hemispheric Activation Process
As we become older, our brain goes through reorganization that is characterized by both advantages and disadvantages.
A young brain is more prone to an asymmetrical activity pattern, in which case the right hemisphere is more active. The brain of a middle-aged person is prone to a profile of activity that involves more brain areas compared to a brain of a young person. It contradicts the hypothesis, which was common in the past, according to which a middle-aged brain is less active. The middle-aged brain tends toward a more symmetrical pattern of activity, which involves the left hemisphere more but does not neglect the right hemisphere altogether. It seems that such a pattern of activity makes it easier for emotions and common sense to live under one roof and integrate with one another.
The Hemispheric Pendulum Movement
The view that links the movement of the cognition’s center of gravity with the emotions’ center of gravity from the right hemisphere to the left hemisphere in the course of our life might serve as an explanation for the changes in the operation pattern of the brain, which seems to match the insight that is common in the field of geometry regarding a necessary and sufficient condition. This view also reflects the spirit of the principle of simplification called “Ockham’s Razor,” according to which the simple explanation that explains the nature of things appropriately is better than a more sophisticated explanation that explains them.
As aforesaid, as people grow older a more cooperative operation pattern is noticed in the brain, such that involves the two hemispheres. Nevertheless, this pattern reflects more usage of the left hemisphere compared to its use during adolescence. According to this hypothesis, each new acquired pattern is born at the delivery room located in the right hemisphere. When it becomes more mature, as a result of constant encounters with the facts of life and critical dialogue with other insights that exist in the living space of the brain, it moves, with due respect, to the residence of the well-established, stable insights located in the left hemisphere. The left hemisphere is the residence of generic insights—the descriptive and guiding ones.
Defining the hemispheric expertise profile does not involve setting strict limits regarding the contents of the pattern. An information pattern that is considered a novelty today will become a familiar pattern tomorrow. The difference relates to the level of familiarity between the brain and the contents of the information pattern at the time of their encounter.
The movement of the mental pendulum from right to left is probably a phenomenon that is at the core of all learning processes. Nevertheless, it does not mean that as we grow older we abandon the right hemisphere. The operation pattern becomes more cooperative, however, and more room is given to the left hemisphere.
Once the quota of patterns stored in the left hemisphere crosses a certain threshold, and “world knowledge,” both descriptive and guiding, has been accumulated sufficiently, the owner of the brain that contains these patterns is able to find his way around, even if the function of the right hemisphere is impaired. He does so based on the reservoir of patterns in the left hemisphere and increasing usage of an approach of patterns identification for problem solving.
Social intelligence prefers the right; various cognitive skills differ from one another in terms of the pace at which the patterns that are related to them wander to the left hemisphere, and there are also some that remain mostly the estate of the right hemisphere. This is the case with social skills, which are sometimes referred to as “social intelligence.” It seems that the spectrum of nuances and variations in the shades of our social world is so broad that they cannot be minimized into a definite number of core patterns. Thus, the main hemisphere that carries the burden of managing our social behavior is the right one. It seems that detecting the “emotional weather” among our fellow humans tends to challenge the familiar patterns, and, similar to real weather, it involves novelties time and time again.
It is generally assumed that damage to the right hemisphere leads to more destructive consequences among children compared to adults, and at the other end of the spectrum of ages the situation is inverted. Among adults, damage to the left hemisphere involves more severe impairments compared to those among children.
Findings that support this hypothesis were found, inter alia, in studies that were conducted among children who underwent hemispherectomy—a broad, radical surgery during which a whole hemisphere, or the lion’s share of a hemisphere, is removed and the patient is left with only one functional hemisphere. Usually such an operation is carried out in an attempt to improve the condition of patients who suffer severe epileptic seizures that cannot be controlled by medications, and the focus that generates them is located within one of the hemispheres.
Regression in brain plasticity, which takes place as we become older, might reflect a withdrawal from the right hemisphere, which seems to be the chief generator of brain plasticity to the fortifications of the left hemisphere. As we climb up the mountain of the years and grow older, the center of gravity of our mental life shifts to the left. As years go by, we all tend to become “left-brained.”
Constant learning hinders the withdrawal of the right hemisphere from the stage of our cognitive world. Constantly dealing with the new hinders the natural move of the cognitive pendulum, which tends, with the years, to spend less time in the right hemisphere and to prefer brain activity in the left hemisphere.
The Hemispheric Activation Profile as Reflecting a Culture
The findings from a series of experiments suggest that students who were raised in western societies tend to see entities as isolated, which can be seen as preferred observation “through the eyes” of the left hemisphere. On the other hand, students who were raised under the auspices of Japanese culture tend to perceive an object as relating to other entities, a tendency that is characterized as observation “through the eyes” of the right hemisphere.
The tendency toward uniqueness and individualism is probably a cultural sugge
stion. This tendency is common in the western world. In eastern Asian countries, however, conformism is common, which is probably a cultural suggestion as well. In this spirit, we can interpret the Japanese proverb “The nail that sticks out shall be hammered down” as a recommendation to adapt oneself to the society.
In this context, the traditional hypothesis, which ascribes analytical skills and serial, reductive processing to the left hemisphere and parallel, holistic processing to the right hemisphere, is raised. Comparing the interpretation of world manifestations to common cultural interpretation raises an interesting possibility of cultural preference for a certain hemisphere’s skills over the other hemisphere’s skills as being culture dependent.
These differences in perception are acquired rather than innate. This assumption is supported, inter alia, by the fact that immigrants from a certain culture to a different culture learn “to perceive things differently” according to the perception pattern that is common in the culture to which they immigrated. It does not mean, however, that a certain perception is better than the other. There are circumstances in life in which a certain perception is more suitable, and other situations in which the other perception is preferable.
Expressions of Impairments in Hemispheric Function
Dr. Roger Sperry, who won the Nobel Prize in Medicine in 1981, based on the research he conducted among people with “split brain” (those who underwent an operation in which their corpus callosum, which connects the two hemispheres, was cut, mostly due to epileptic seizures that could not be controlled by medications), believed, based on his studies, that each hemisphere has a mental sphere of its own. As he once put it, “The joys and senses of the right half of my brain are too great for the left half of my brain to put into words.”
