You have probably heard of “right-brained” people and “left-brained” people, and that right-brained people are creative and left-brained people are analytical. A great deal of pseudoscience has been created around the right brain-left brain dichotomy. Try to forget this, and ready your mind to start fresh with a new, more subtle conception of right brain and left brain.
We think of handedness–as in right-handed or left-handed–as an arbitrary variation in humans. There has been a wealth of research into handedness throughout the animal kingdom. It turns out that lateralization of functions–specialization of left and right hand sides–is a fundamental archetypal pattern preserved across all vertebrates. This reflects the lateralization of brain function.
Psychologist Jordan Peterson offered his interpretation of the dichotomy, which is a good starting place:
General PrinciplesThe “left brain logical, right brain creative” popular dichotomy is inaccurate. Better dichotomy system:
| Left Brain | Right Brain |
| social | individualistic |
| humanism | group affiliation |
| individual empathy | individual loyalty |
| empathizing | systematizing |
| bottom-up | top-down |
| local | global |
| local association | distant association |
| inductive | deductive |
| feed-and-breed | fight-or-flight |
| quietude | arousal |
| optimism | skepticism |
| curiosity | acclimation |
| lexical | affective |
| supportive | critical |
| situational | universal |
| utilitarian | affective |
| instances | classes |
| detailed | abstract |
| procedural | generative |
| heroes | archetypes |
| tools | animals |
| exploration | caution |
| musical skill | music listening |
| expertise | creative insight |
| fear | anger |
| deception | hate |
| daytime | nocturnal |
| activation | inhibition |
| exploitation | conservation |
Right brain is a plausible candidate for Jung’s Shadow. This is apropos given the right brain’s personality:
Jung also believed that “in spite of its function as a reservoir for human darkness—or perhaps because of this—the shadow is the seat of creativity“;[9] so that for some, it may be, “the dark side of his being, his sinister shadow…represents the true spirit of life as against the arid scholar”.
But, Jung’s overall descriptions of the shadow seem to overlap with ideas that fit better with limbic, basal ganglia, hypothalamic, and midbrain areas. The shadow may be too broad to be a useful concept.
Animal Theory
The wiring of the brain is crossed such that left brain dominance leads to right-handedness, and right brain dominance leads to left-handedness.Solitary animals are right-hemisphere dominant, social animals are left hemisphere-dominantSolitary animals are left-pawed, social animals are right-pawed due to cross-wiring of the brain to the opposite side.The ancient pineal gland is connected to the third parietal eye of ancient life forms (as seen in arthropod eyes today). This parietal eye is connected to the left habenula in primitive vertebrates such as the lamprey. Frogs (decidedly nocturnal) have an overdeveloped single right habenula. The parietal eye to habenula asymmetry supports the left brain’s connection to daylight.
Animal Examples
Planarians come in left-handed and right-handed varieties, that display preferences for rolling one way or the other when a stimulus is presented.
Honeybees show differential behaviors depending upon whether their left or right antenna are presented with a stimulus.Blue whales roll right when feeding.Polar bears (solitary) are left-pawed.Chimps (social) are right-handed, orangutans (solitary) are left-handed.Schooling fish display right side preferences, solitary fish display left-side preferences.Marsupials (mostly solitary and nocturnal) are left-handed. Marsupials are the only mammals that lack a corpus callosum, which is the main tract through which the left brain communicates with the right. Marsupials do not have the rich social experience of other mammals with a corpus callous.Female housecats (sociable) are right-pawed. Male tomcats (solitary) are left-pawed.Dogs are mostly right-pawed. Left-pawed dogs have been noted to have more negative emotions.Wolf pack alpha males tend to be left-pawed (solitary). Lone wolves are left-pawed. The rest of the pack is typically right-pawed.
Developmental Biology
The normal progression in social animals is for the right brain to develop first, then the left. The left brain ultimately wires into the right via the corpus callosum, and establishes dominance over it.When this brain development is disrupted, left-handedness (right brain dominance) results, e.g.- Oxygen deprivation of babies can cause left-handedness- Autism and psychopathy is associated with left-handednessThis may explain the superstitions about left-handedness being associated with the devil.
Handedness in Humans
Males are 3x frequently left-handed than females. Males are more subject to retardation of left brain development due to mother’s immune attacks: autism.Gay men are 40% more frequently left-handed than straight men. Each subsequent male child of a mother is progressively more likely to be gay: maternal immune system more sensitized.Ambidextrous people are more frequently bisexual, especially women. Ambidextrous people also have higher schizophrenia incidence.Autistic spectrum people are up to 50% ambidextrous.
Conclusions
In some chosen people, the normal progression into a boring social left-brain dominant person is disrupted. The creative individualistic right brain is liberated from the mundane social world. These right-brained freaks are more likely to be male and left-handed because of the immunological vulnerability described earlier.Females have more integrated brains, which means the left hemisphere is more developed and reaches back across the corpus callosum to dominate the right. Males are more compartmentalized within right and left brains.This is related to the “females empathize, males systematize” cognitive styles. I.e. left social brain, generalizing right brain.Left dominance explains the female advantage in language, which is left-lateralized.Left compartmentalization explains the male advantage in mathematics and spatial mental rotation, which is a left angular gyrus function.Male right and female left dominance in emotional experience (men are from right amygdala/Mars, women are from left amygdala/Venus) is a central gender difference.Male parietal lobe and female medial prefrontal cortex dominance is another central gender difference. (not a right-left, but an anterior/medial – posterior/lateral difference)
http://neuropolitics.org/conservative-left-brain-liberal-right-brain.htmThis article got the political-brain lateralization reversed, but is solid otherwise. I think the split brain patient was morally provoked by Watergate, and therefore resented Nixon.
The left AI and ACC are more active during feelings of romantic love and maternal attachment. The AI and ACC were activated on both the right and left sides while watching pain being inflicted on a loved one while only the right AI and ACC that is elicited during subjective feelings of pain; this supports the association of right AI in aroused (‘sympathetic’) feelings and left AI in affiliative (‘parasympathetic’) feelings.
Negative pictures activated the left hemisphere in women more than in men, and the right hemisphere in men more than in women when shown unpleasant images.
Watching people behave badly by breaking moral codes most significantly activates the right parahippocampal gyrus, the right medial frontal gyrus, and left amygdala.[11] Watching emotionally negative situations most significantly activates the right amygdala.
People with left inferior frontal lobe damage produced less facial expression and could not analyze emotional situations as well as those with right frontal lobe damage especially with fear and disgust.[n 9] The left inferior frontal gyrus(IFG) plays an important role in anger while the right IFG plays a larger role in disgust.[14]
Patients with dorsolateral frontal cortex lesions have difficulty discerning propositional attitude. Patients with left lesions show further increased impairment.