Maybe it is just coincidence that the political affiliations of "left" and "right" correlate with handedness. Maybe not. Michael Gazzaniga, Roger Sperry, and Joseph Bogen were researching the impact of brain-splitting operations, and encountered a patient named Paul. Paul had a commissurotomy, and his right and left brains no longer communicated with each other.
Since Paul had an enhanced language capability in his right brain, he was able to express his opinions, whereas most recently split-brain patients would not be able to vocalize the opinions of their right hemispheres. Paul's right brain wanted to be a racecar driver while his left brain wanted to be a draftsman. This study was done during the Watergate scandal, so the research team naturally threw in a question about Richard Nixon. Paul's right brain expressed dislike for Richard Nixon, while his left brain liked him.
Left and Right Hemisphere Average Scores by Political Cohort It gets worse. In another split-brain case, while the patient was fighting with his wife, his left hand was trying to strangle her while his right hand was trying to stop his left hand. Had this man's brain not been split, no doubt the struggle would have been waged within his brain itself, and not between his hands. This illustrates how differently the left and right brains behave when they are not influenced by each other. The very structured nature of the left brain maintains an uneasy alliance with the right brain, which is in its own world, albeit more closely connected to that world than the left brain.
The left brain is a dopamine-oriented world unto itself. Dopamine is a molecule that works in conjunction with the several types of dopamine receptor cells that respond to nearby emissions of what else---dopamine. The number of dopamine receptors in the left brain is higher than the right brain, and this imbalance is enhanced during puberty, particularly in males. Dopamine is a key neurotransmitter, and facilitates the functionality of fine motor skills, language, arithmetic, and monosemantic processing.
By monosemantic, we mean the "single-mindedness", or single meaning of a particular memory or stimulus. For example, let's take the word "God". In the left hemisphere, the concept of "God" is monosemantic, and is whatever the left brain has been conditioned to mean. To the left brain, "God" maybe Jesus Christ, Allah, Yahweh, or some other unambiguous concept. In contrast, the right hemisphere tends to be polysemantic or ambiguous, and tends to process many different meanings of "God" and searches for links between its meanings of "God" and hitherto unrelated stimuli. To the right hemisphere, "God" is much more ambiguous.
The monosemantic nature of the left brain is consistent with its syntactical and arithmetical functionality. Broca's area, or the language processing center of the brain, is a complex of nerve cells that structure a thought into a syntactically correct sentence. Broca's area is predominantly in the left hemisphere, even for left-handed people. The scattered and polysemantic thinking of the right brain is not very good at producing language or arithmetic. To the left brain, 2+2=4. To the right brain, maybe it is 4, maybe not. The right brain will eagerly search for scenarios in which 2+2 does not equal 4, and might be disappointed when it doesn't find any.
The right brain is a norepinephrine-oriented world, and as such, has certain advantages over its rigid next door neighbor. Norepinephrine is another neurotransmitter, not too unlike dopamine. Both act as stimulants to the nervous system. Norepinephrine receptors are very responsive to the external environment. The norepinephine receptors facilitate selective attention, and are very sensitive to unusual stimuli. In new environments, the right brain's norepinephrine system is running wild, making connections and analyzing multiple potential meanings in the flood of new stimuli. The left brain is in a bit of trouble here, as its structured dopamine-fueled approach can't perform as comprehensive analysis or relate information as well as the right brain can.
The left-brain seeks to avoid internal contradictions in its analysis of the environment. It tends to limit the analytical result to a set of predetermined outcomes that are consistent with its conditioning. This thinking approach works well in stable and non-threatening environments. The left-brain tends to bend reality to fit the way it wants to process it. There is a certain expectation that the left-brain has of reality, and pre-determinism in responding to the environmental clues is its natural operating mode. Time-orientation is a natural outcome of the left-brain's propensity for pre-determinism.
In contrast, the right brain has a lower propensity for pre-determinism, and is not as inclined to drive the information analysis to a particular outcome. It also provides a varied neural network framework for connecting information together, and exhibits less linear information retrieval processing than the left brain. Its thinking approach promotes information connectivity and polysemantics. However, it can lead to more ambiguous and complex outcomes.
Let's not think that these are two opposite but complementary hemispheres that are highly specialized to perform their respective duties like machine parts. The differences between the brains are sometimes subtle, both anatomically and functionally. The left brain can perform rapidly when integrating and analyzing environmental information if that information is discreet and more easily categorized. The right brain can understand a lot of language, if it is not too complex.
The right brain does very well with new and unusual stimuli. It provides the comprehensive polysemantic analysis, and the left brain benefits from that analysis. The right brain has positioned the left brain to adapt this information more effectively into its structured analytic processes, and even make changes to the left brain's monosemantics. This process is the basis for man's eternal progression in the structured understanding of the mysterious world.
The left brain is more electrically active than the right brain. The reasons behind this are still under investigation, but the ascending reticular arousal system, or ARAS, is the apparent culprit here. The reticular formation, which lives in the brainstem, has ascending fibers into the cortex and provides the energy to light it up. It is sort of like an electric cord for your toaster. Sever this connection, and the brain becomes comatose, eventually leading to death. The connectivity between the left brain and the ARAS exceeds that of the right brain.
The left brain draws more current from the ARAS, and speculation is that its monosemantic nature requires more activation to support the more structured connectivity. Conversely, the right brain seems to run on its own, as its neural network is all over the place, passing electrical current all around, not varying much even when in focused analysis. Additional activation from the ARAS will not improve right hemisphere functions. However, it will suffer the same fate as the left hemisphere when severed from its power source.
But don't let the left brain's propensity for logic and syntax fool you into believing that it is the "sane" hemisphere. On the contrary, it is just that structure that can lead to extreme disconnection from the real world. If the left hemisphere becomes hyperactive, it can construct delusions, paranoia, hallucinations, and a closed world unto itself. This hyperactivation of the left hemisphere is found repeatedly in schizophrenics. The nature of the left hemisphere is to build monosemantic models of the world, and when hyperactive, its monosemantic modeling connects memories and stimuli nonsensically. The left brain's external-sensory processing and analysis functions are also impaired, thus producing the closed-world effect. The left brain is disengaging from the real world.
The left brain is at a disadvantage in maintaining connectivity with the real world due to its linguistic orientation. The right hemisphere builds an image-based spatial map of the world, the left builds a verbally-based logical map. The right hemisphere focuses on shapes and spatial relationships, the left on verbally expressed details and categorizations. The right hemisphere encodes sensory information in images, and the left encodes verbal cues. The right hemisphere's compulsion for scanning the environment makes it hard for it to disengage from the reality. The right hemisphere's polysemantic and spatial orientation make it a natural for creative behavior.
The split brain experiments would reveal some very curious distinctions between the two hemispheres. Michael Gazzaniga devised numerous experiments to test the two brains, and the sooner after surgery the better, since the two brains will try to acquire the skills that were so rudely lost when the brains were split. When the right hand (left-brain) was instructed to draw an object, it got lost. It tried to draw. But it lost track of the object it was supposed to draw. This curious behavior indicated that the left brain could not translate the visual object into motor commands to its right hand, even though the left brain is very adept at motor control. The left brain could not generate or communicate spatial relationships.
Jerre Levy developed several ingenious experiments that would leave no doubt as to the dramatic differences between left and right brains. One experiment would take two half-face photos of two different people and flash them simultaneously to opposite sides of the brain, with each hemisphere seeing only one of the half-faces. The subject was then asked to point out the full-face photo that the half-face photo came from. The subject would invariably pick out the half-face seen by the right brain. Oddly enough, both the right and left hands picked out the one the right brain saw. Somehow, even though the corpus callosum was severed, certain information was still being relayed between the brains, presumably via the brain stem.
The only way Levy could get the left hemisphere to respond to the faces was to provide a verbal clue with the physical features, such as "Dick has glasses". With verbal clues, the left brain was able to pick out the full facial picture, but with much less accuracy, primarily because of the non-comprehensive nature of the verbal clue. The left brain could see the face and a pair of glasses on it, but it could not definitively integrate the facial image along with the glasses. The left brain could translate the visual image into verbal clues, but it couldn't store and retrieve the aggregate image as a visual memory. However, the right brain did it naturally.
Still more interesting was when the subject was asked to pick out a picture that rhymed with two other simultaneously flashed pictures, the subject would give precedence to the left brain, as a verbal analysis must be done for this test. But when a non-sense word was flashed, such as "noes", the subject gave precedence to the right brain's nonsensical word picture. It seems we read regular words with our left brain, and nonsensical words get processed as holistic images in our right. Levy's brilliant work would include the split image of a scissors and a cake. When asked to point to a similar item, the left hemisphere would match the scissors with a thread, and the right hemisphere would match a cake with a hat. The left hemisphere selected based on logical relationship, and the right based on shape. This was consistent throughout the testing.
Further research would confirm the left brain's inability to make and store spatial coordinates of objects, while the right hemisphere handled them like a well-oiled machine. Split-brain research would get a boost from Stuart Dimond, who tested the attention spans of the two hemispheres, and found something rather startling. After informing his subjects that they should watch for signal flashes to the right and left brain, he found that the left brain seemed to pass out for about 15 seconds before becoming aware again. The left hemisphere was mixing attention to the external environment with attention to itself. The left brain was checking up on the environment in between focusing in on its own little world. And worse, the left brain seemed to lose track of what it was doing before it blanked out. In contrast, the right brain maintained a much more consistent attention span without the blackouts.
A key musical experiment was performed by Thomas Bever and Robert Chiarello, this time, on normal subjects. They played a musical piece, and during the initial exposures to the music, the subjects demonstrated a right hemisphere-left ear preference for listening. After repeated exposures, the subjects then developed a left hemisphere-right ear listening preference. This right to left shift of hemispheric preference for repeated musical stimuli indicates both an inhibition of responsiveness to repeated stimuli by the right brain, and increased analysis of detail by the left. The brain exhibited a flow, as the left brain functioned to adapt some sort of analysis of a recurrent stimuli, while the ever watchful right brain would lose interest in it.
While the musical experiments indicated two stimuli processing hierarchies in the right and left brains, Dimond and Linda Farrington were making headway into how the two brains processed emotion. They picked out a Tom and Jerry cartoon, a travel film, and a film of a surgical operation, and showed it directly to the right hemisphere-left eye, or left hemisphere-right eye, by using contact lenses to block the alternate eye's view. While this is not as good as testing a split brain, it was still very revealing. The right brain judged the comically violent Tom and Jerry cartoon and surgical film as more unpleasant and even horrific. Dimond attributed a "special role" for the right brain in processing emotion. The same level of response did not occur with the left.
In further research, it was found that the left brain became more talkative when the right brain was unconscious, but it lost its vocal intonations, and the speech became monotone and lifeless. Apparently the right brain is telling the left brain to shut up. The left brain cannot resolve the emotional qualities of speech, nor even tell if a man or woman is speaking. But even given the left brain's inability to inject or ascertain emotion in speech, it is the happy hemisphere. It has a much better outlook on life, and tends to be cheerful, even though detached from reality. The right hemisphere is not. On the contrary, the right hemisphere has quite a negative and sullen outlook of the world, when not influenced by the left side.
As noted in the beginning, Paul, the split brain patient that had contrasting hemispheric emotions about Richard Nixon, followed this pattern exactly. His right brain disliked Nixon and his left brain liked him. This is certainly no indication that Paul's left brain was conservative and his right a liberal. Paul's right brain could have disliked everyone, not just Nixon. But more research would uncover further evidence that both hemispheres do indeed exhibit tendencies to promote either conservative or liberal political affiliations, and in unexpected ways.
A team of UCLA researchers led by Marco Iacoboni have been mapping the electrical activity of the neural structures in the brain as they respond to miscellaneous events, and had the subversive idea to show controversial political commercials to of all things---Democrats and Republicans. One such commercial was footage of the smoldering Twin Towers site after 9/11. During the viewing of the scenes, the electrical activity of the various brain regions were measured, and some startling behaviors were revealed. It seems that the Democrats had higher average amygdalar activations than the Republicans.
The amygdalae are small almond-shaped structures in the temporal lobes on both hemispheres of the brain that make us afraid of things, along with several other structures. It keeps us from jumping off a cliff unexpectedly or informing our boss that he is an incompetent moron. A rat with amygdalar damage will snuggle right up to a cat and try to get a hug. The amygdalae are multi-purpose structures that support both aggressive and aversive behaviors, and when removed, dampen both responses. The amygdalae mature quickly in the infant, and provide an early warning response system for newborns. However, they are low on the evolutionary chain of limbic system structures, and are relegated to crude but quick analysis and response. The ventromedial cortex is at the high end of this chain, and provides the "thinking" for our emotional limbic system.
The amygdala has been the focal point of some other fascinating research, namely the famous Hart and Cunningham et al research that focused on the amygdalar reactions to images of other races. It seems that the amygdala in Caucasians is more active while viewing African-American faces, and vice-versa. However, this was based on a small sample set with contrasting results for different trial stages. Further studies would note differences in purely subconscious amygdalar responses as opposed to longer term cortical activation, which was much less responsive to racial images.
The amygdala in the right hemisphere functions differently than its leftward twin, and this difference coincides with the general differences in hemispheric processing. The left amygdala is entrenched in the language-based world of the left brain, and can be taught to fear something based solely on verbal clues, without having any direct contact. If someone tells you there is a shark in the ocean, your left amygdala will activate when you think about going swimming. However, if you see a shark swimming in the ocean, your right amygdala will activate as you watch it.
It seems the right amygdala is more responsive to existing environmental threats, and the left amygdala to verbal fear conditioning and anticipated threats. The right amygdala is more reactive than its left twin to other's facial expressions and non-verbal vocalizations such as crying and laughing. More importantly is the right amygdala’s specialization for aversive emotions. The left amygdala, like the left brain, is the more positive amygdala. The right amygdala is also the anxious amygdala, and has been implicated in anxiety disorders with some help from the left amygdala.
The Empathetic Liberal
Experiments with rhesus monkeys would prove that the evolution of empathy is a very long one. These little monkeys were given the option of doubling their food source while simultaneously shocking their fellow monkeys, or eating half as much and letting their friends live an electricity-free existence. Using a system of chains, batteries, and automatic food dispensers, the experimenters found that two-thirds of the monkeys preferred the empathetic less-food option. In a few cases, these monkeys were even starving themselves to avoid hurting their little buddies. They were also less likely to shock another monkey if they had experienced a shock themselves, and were less likely to shock any monkey they knew, although they might not be so kind if one of the scientists were thrown into the cage.
Empathy is fundamental to any species that raise their young. As it turns out, the right brain is critical in early childhood development, and is dominant during the first three years of life, until the left brain has its growth spurt and becomes dominant as the child develops its language capabilities. The first few years are a right-brained wonderland between mother and child, as non-verbal communication is vital. The right brain's gift for emotional recognition and communication is well suited for mothering. The irritating nonsense words uttered by parents to their infant children during this stage are a product of the right brain. The right brain makes a mess out of the English language.
But empathy has expanded far beyond the confines of mother and child, to incorporate people we have never had direct contact with, and even other species we have not even seen. Empathy can be genetically motivated or contact-based, such as that we experience with our family and friends. It can also be abstract, which maybe something we experience for people subjected to a tsunami, poverty, a disease, or an unborn baby. But we need to look no further than our right brain, which is the dominant hemispheric source of our empathetic nature.
The right brain has a significantly expanded orbital prefrontal region, which is primarily responsible for socially based emotional processing. Socially based emotional processing involves the detection of facial expressions, auditory emotional communications, touch, and smell. This enlarged area in the right brain senses pain in others and stimulates our sense of empathy. The breadth and strength of empathy reactions highly engage this expanded orbital prefrontal region.
Impaired empathy would be observed in patients with right prefrontal cortical damage and right posterior damage. Impaired empathy functions would also be observed with left prefrontal cortical damage, but left posterior damage had no effect. Maximal empathy impairment would be observed in patients with right prefrontal lesions. Does the liberal have a heightened sense of abstract empathy for others? A theory of right-brained empathetic liberalism might include specific areas in the right brain, such as the orbital prefrontal cortex, that are more programmed for social empathy in large groups.
However, what we found in our initial survey implies hemispheric biases that extend beyond social empathy processing. We found asymmetries in arithmetic, language, emotional processing, and belief-bias. The first research paper presented on this website outlines some of our findings and interpretations of the results.
Charles Brack
March, 2005