Daily Journal Language Arts Prompts Left Brain Right Brain
The Truth About The Left Brain / Right Brain Human relationship : xiii.7: Creation And Civilisation Is the idea that the left hemisphere of the encephalon is more logical and the correct more than intuitive a scientific fact or a cultural fiction? Commentator Tania Lombrozo turns to an expert for answers.
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The Truth Almost The Left Brain / Right Brain Human relationship
It'due south fourth dimension to rethink whatsoever you lot thought you lot knew nigh how the right and left hemispheres of the encephalon work together. iStockphoto hide explanation
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Information technology's time to rethink any yous thought you knew about how the right and left hemispheres of the encephalon work together.
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Sometimes ideas that originate in scientific discipline seep out into the broader civilization and take on a life of their own. It's all the same common to hear people referred to as "anal," a Freudian idea that no longer has much currency in contemporary psychology. Ideas like black holes and quantum leaps play a metaphorical office that'southward only loosely tethered to their original scientific meanings.
What about the idea that some people are more right-brained and others more left-brained? Or that there's a distinctive analytic and verbal manner of thinking associated with the left hemisphere of the brain, and a more holistic, creative manner associated with the correct? Are these scientific facts or cultural fictions?
An infographic reproduced just last calendar month at Lifehack.org, for instance, promises to explain "why you act the way you lot practise" by revealing "which side of your encephalon you tend to utilize more." An article at Oprah.com explains "how to tap into right-encephalon thinking." And decades of enquiry using behavioral and neuro-scientific techniques practice reveal fascinating and systematic differences across brain regions.
On the other hand, some recent headlines challenge the left brain / correct encephalon dichotomy. Ane highly publicized paper, summarized at The Guardian, failed to find evidence that individuals tend to accept stronger left- or correct-sided brain networks. A new book past Stephen M. Kosslyn and Chiliad. Wayne Miller argues that the left / right encephalon divide is largely bogus, and should instead be replaced by a height brain / bottom brain stardom.
So while in that location's something deeply compelling about the clear-cut, right-brain versus left-brain nomenclature (or is that just my left hemisphere speaking?), we accept expert reasons for skepticism. The real story, every bit you might expect, is a bit more complicated — but arguably more interesting — than the infographics and popular headlines seem to suggest.
To become a clearer picture of what we do and don't know most hemispheric brain differences in humans, I was fortunate to have an opportunity to interview a leading cerebral neuroscientist, Kara D. Federmeier, whose research focuses on language, retentivity and hemispheric asymmetries throughout the lifespan. Dr. Federmeier is a professor of psychology at the University of Illinois at Urbana-Champaign, where she'due south also affiliated with the Neurosciences Program and The Beckman Plant for Advanced Scientific discipline and Technology. (And, full disclosure, she was also one of my kickoff scientific mentors and co-authors.)
One idea that's often heard in popular discussions of psychology is that the left encephalon is the seat of linguistic communication and more "logical," while the right brain is more artistic. Is there any truth to this thought?
Ane problem with answering this question is that we would first have to agree on what "logical" and "artistic" even mean. So let's consider a (relatively) more well-defined case: math skills, which are frequently taken to be office of what the "logical" left hemisphere would be practiced at.
There are different kinds of math skills, ranging from beingness able to estimate which of 2 sets of things has a greater number of items, to counting, to diverse types of calculations. Inquiry shows that, overall, the abilities that brand up math skills arise from processing that takes place in BOTH hemispheres (especially the brain expanse in each hemisphere that is known equally the intraparietal sulcus) and that impairment to either hemisphere can crusade difficulties with math. A left hemisphere reward for math is mostly seen for tasks like counting and reciting multiplication tables, which rely heavily on memorized verbal information (thus, not exactly what we remember of every bit "logical"!). And there are right hemisphere advantages on some math-related tasks as well, especially estimating the quantity of a set of objects. This kind of blueprint, in which both hemispheres of the brain make critical contributions, holds for most types of cognitive skills. It takes two hemispheres to be logical – or to exist creative.
The claim that the left hemisphere is the seat of language, still, is a little different. That thought comes from observations that damage to the left hemisphere (for instance, due to a stroke) is often associated with difficulties producing language, a problem known as aphasia. Similar damage to the right hemisphere is much less likely to cause aphasia. In fact, for near people, the left hemisphere does play a much more of import office in the ability to speak than the right hemisphere does.
Nevertheless, this does not mean that the correct hemisphere is "nonverbal." My laboratory studies the hemispheres' ability to encompass (rather than produce) linguistic communication, and we, like others, have shown that both hemispheres can effigy out the pregnant of words and sentences – and that they have differing strengths and weaknesses when it comes to comprehending. So, like other circuitous skills, the power to empathise what nosotros read or what someone is saying to us requires both hemispheres, working together and separately.
Early studies of hemispheric asymmetries oftentimes relied on "divide-brain" patients who had the corpus callosum — the bundle of neural fibers that connects the 2 hemispheres — severed as a handling for severe epilepsy. In such studies, information could be provided to a single hemisphere at a fourth dimension by presenting people with input to one side of the visual field, since the right visual field is processed by the left hemisphere, and vice versa.
Your lab uses contemporary neuro-scientific techniques, such as measures of brain wave activity (EEG and ERP) to investigate hemispheric asymmetries, and typically does so in individuals with intact brains. How practise you do then, and do your findings corroborate or claiming earlier inferences fabricated from the behavior of split-brain patients?
Nosotros actually utilize the same basic technique, known as "visual one-half field presentation."
As an aside, I should point out that many times people misunderstand and think that each Center is connected to a different hemisphere. That's not truthful. (Information technology would make our studies so much easier if it were, since we could simply enquire people to close i eye!) Instead, one-half of the information coming into each eye goes to each of the hemispheres, with the result, equally y'all point out, that if you are looking forrad, things you run across to the right of where you are looking are beingness picked up initially past your left hemisphere and things to the left by your correct hemisphere.
To look at hemispheric differences, nosotros ask our participants, who are usually either college students or retired adults, to look at the center of the screen. Nosotros then display words (or pictures, or other types of stimuli) fairly rapidly – so people can't move their eyes fast plenty to fixate them directly – to the left or the correct side of a computer screen. By comparison how people answer (for instance, whether they can accurately remember a word) when it was processed first past the left hemisphere versus by the right hemisphere, we can test ideas about what each hemisphere is capable of and whether one hemisphere has better, or unlike, abilities compared to the other.
Ofttimes, we besides measure brain electrical activity in these experiments because that provides rich data almost how processing is unfolding over time: we can runway what happens as the eyes send data to visual processing areas in the brain, as people pay attention to a discussion, access its meaning from memory, and add this new information into their unfolding agreement of a sentence, and as people, in some cases, make up one's mind how to reply so set up to press a button to register their response. With electrophysiological measures we can thus observe out non only THAT the ii hemispheres practise something different but WHEN and HOW.
In general, the kinds of hemispheric differences that were uncovered in split-encephalon patients have been replicated (and and then extended) using these techniques in people with intact brains. This sometimes surprises people, including my beau cognitive neuroscientists. The idea that the two hemispheres perceive things differently, adhere different significance to things, obtain different meanings from stimuli, and, sometimes, make different decisions about what to do seems like it should be an exotic side consequence of the carve up-brain condition. When the hemispheres are connected, don't they just share all the information and operate in a unified fashion?
The respond is, no, they don't.
They don't, in office, considering they can't. Processing within each hemisphere relies on a rich, dense network of connections. The corpus callosum that connects the hemispheres is big for a fiber tract, just it is tiny compared to the network of connections inside each hemisphere. Physically, then, it doesn't seem feasible for the hemispheres to fully share information or to operate in a fully unified manner. Moreover, in a lot of cases, keeping things split is (literally!) the smarter way for the hemispheres to role. Dividing up tasks and allowing the hemispheres to piece of work semi-independently and take different approaches to the same problem seems to be a good strategy for the brain ... just as it ofttimes is in a partnerships between people.
It makes sense to have specialized brain regions, just as it makes sense to have divisions of labor in other areas of life. But why have specialized hemispheres? In other words, do you think in that location's something full general that can be said nigh the sorts of processing that occur in the left hemisphere versus the right hemisphere, or is each only a constellation of somewhat distinct, specialized regions?
Specifically how and why the hemispheres differ remains a mystery. They are actually remarkably similar physically, and this is i reason I think that studying hemispheric differences is disquisitional for the field.
Over the by decade or and then, a lot of endeavor has been put into "mapping" the human brain – that is, linking areas that differ anatomically (have dissimilar inputs, outputs, types or arrangements of neurons, and/or neuropharmacology) to different functions. From this, we hope we tin learn something well-nigh how and why these anatomical differences matter. Notwithstanding, in doing this, the field has also uncovered a lot of hemispheric asymmetries – cases in which, for example, a left hemisphere brain expanse becomes active and its right hemisphere homologue (with the Aforementioned basic inputs, outputs, etc.) is much less agile (or vice versa). This should really surprise us: here are two brain areas that are essentially the same on all the dimensions the field is used to thinking nigh, yet they behave strikingly differently. There must be physical differences between them, of grade – merely so, this means that those "subtle" differences are much more critical for function than the field has appreciated.
My own view is that studies of hemispheric differences volition help to movement the field abroad from thinking in terms of mapping functions onto localized brain areas. I believe that cerebral functions arise from dynamically configured neural networks. On this view, the function played by whatsoever given brain area is different depending on the state of the network of which information technology is currently a part, and how activity unfolds over fourth dimension often matters more than where it is in the encephalon.
Why do the hemispheres differ? I call back it is because even small differences in something like the strength with which areas are continued can lead to very different dynamic patterns of activation over time – and thus dissimilar functions. For language comprehension in item, my work has shown that left hemisphere processing is more influenced by what are sometimes called "acme-downwardly" connections, which ways that the left hemisphere is more likely to predict what word might be coming upward next and to have its processing affected past that prediction. The correct hemisphere, instead, shows more than "feedforward" processing: it is less influenced by predictions (which tin make its processing less efficient) simply then more than able to afterward remember details about the words it encountered. Because of what is probable a difference (possibly minor) in the efficacy of particular connections within each hemisphere, the same brain areas in the 2 collaborate differently, and this leads to measurable and important asymmetries in how words are perceived, linked to meaning, remembered, and responded to.
This is unlikely to be the just difference between the hemispheres, of form. But I think the respond to your question is that what we run into beyond the pattern of asymmetries is neither a random drove of unrelated differences nor divisions based on 1 or even a small prepare of functional principles (due east.g., the left hemisphere is "local" and the right hemisphere is "global" ... some other pop 1). Rather, some of the underlying biological science is skewed, and this has far reaching consequences for the kinds of patterns that tin be set up over time in the two hemispheres, leading to sets of functional differences that we tin hopefully eventually link systematically to these underlying biological causes, and thereby deepen our understanding of how the brain works.
What's surprised you nigh about the hemispheric asymmetries you've found (or failed to find!) in your ain research?
One of my favorite findings came from an experiment in which we used adjectives to change the meaning of the aforementioned substantive. For case, the word "book" in "green book" refers to something concrete – that is, something for which it is like shooting fish in a barrel to create a mental image. Yet, given "interesting book" people at present unremarkably call up about the content of the volume rather than its concrete form, so the aforementioned word has go more "abstract" in meaning.
A lot of research shows that physical and abstruse words are processed differently in the brain. We wanted to see if those differences could be institute for exactly the same word depending on what it was referring to, and whether the two hemispheres were similarly affected past concreteness. We found in this experiment, equally nosotros had previously in many others, that the left hemisphere is very sensitive to the predictability of word combinations. Fewer nouns tin get with "greenish" than with "interesting," and brain activeness elicited in response to "book" reflected this when the words were presented initially to the left hemisphere.
Withal, to our surprise, information technology was the right hemisphere that elicited imagery-related encephalon activity to "green book" compared to "interesting book." Thus, although the left hemisphere is clearly important for linguistic communication processing, the right hemisphere may play a special role in creating the rich sensory experience that often accompanies linguistic communication comprehension ... and that makes reading such a pleasure.
Another popular thought is that some people are more "left brained" and others more than "right brained." Is there any evidence for individual differences in the extent to which people rely on one hemisphere versus another? More generally, what kinds of private differences do you lot see in hemispheric specialization?
There are certainly individual differences in hemispheric specialization beyond people, but they are very difficult to reliably determine. Where this matters most is in medical contexts: when people are going to have encephalon surgery (e.1000., for epilepsy or tumor resection), physicians would like to brand sure that in removing certain brain tissue they are non going to disrupt disquisitional functions like language.
Equally I mentioned already, virtually of the time the left hemisphere is more important for speaking, for instance, just that isn't true in absolutely everyone. In order to determine if a person's left or right hemisphere is more important for their linguistic communication production, physicians utilize things like the WADA test, in which a barbiturate is injected into ane hemisphere to temporarily shut information technology down, allowing the physician to encounter what each hemisphere can exercise on its own. This is apparently a very invasive examination (and not perfect at that). If information technology were possible to instead effigy out whether someone relied more on their left or right hemisphere by having them look at a spinning figure or answer a few questions, that would obviously be preferable ... but it doesn't work.
There are, of course, differences in how people larn and remember, what they similar, and what they are like (although, since everyone'south encephalon is unlike, I think the similarities are actually more surprising than the differences). Some of these differences may arise because of individual differences in how the hemispheres are organized or which hemisphere tends to exist used in detail circumstances. Given that the hemispheres practise operate somewhat independently, the question of how their contained processing is eventually combined and/or which hemisphere gets to "take control" of processing for a particular task is i that nosotros are just kickoff to sympathize. (In some cases, split-brain patients' hands – one controlled by each hemisphere – literally fought for control of a item task; it is intriguing to imagine that kind of struggle routinely taking place internally for anybody else!)
However, information technology seems safe to say that for the near part we all use both sides of our brains almost all the time. We practice know a few factors that influence how functions are lateralized and how much they are lateralized. For example, having a "reversed" laterality (with, for example, control of spoken language in the right rather than the left hemisphere) is more likely for left-handed than right-handed people (although information technology is important not to overgeneralize from this: the vast bulk of left-handed people have the typical lateralization pattern). Moreover, differences have been seen amongst correct-handed people depending on whether or not they have left-handed biological relatives; this is something my lab is kickoff to explore. Once more, small-scale biological shifts, caused in part past (complex) genetic differences, tin can lead to different functional patterns, including whether a function tends to be very lateralized or accomplished by both hemispheres.
I will finish with i terminal fact about hemispheric differences that many people may non be aware of, and that is that lateralization of function changes with normal aging. The kinds of lateralized patterns of encephalon activity I mentioned earlier when talking virtually brain mapping studies are more common in young adults. Across many types of tasks and many brain areas, these lateralized patterns tend to switch to bilateral patterns in healthy older adults.
Is this because older adults have ameliorate learned how to be both logical AND artistic? Perhaps :-). It is actually difficult to know when this kind of a shift is helpful – for example, bringing extra processing resources to bear on a task to compensate for age-related declines in office – versus when information technology might be a sign that the brain is only less proficient at maintaining a salubrious sectionalization of labor. Understanding hemispheric specialization is thus also important for discovering ways to aid u.s.a. all maintain ameliorate cerebral functioning with historic period. This is something my laboratory actively investigates, aided by support from the National Institute of Aging as well every bit the James Due south. McDonnell Foundation.
Finally, can you recommend any accessible resources for readers who want to learn more nearly hemispheric asymmetries?
My own interest in hemispheric differences was sparked, in part, by books like Left Encephalon, Correct Encephalon by Sally Springer and Georg Deutsch and Hemispheric Asymmetry: What'south Correct and What's Left by Joseph Hellige. These are accessible books written past scientists and well-grounded in the research – although both books are now more than a decade old, so don't reflect current developments in the field. Unfortunately, I don't know of more recent books that are comparably reliable and accessible.
Some readers may exist interested to read journal articles on the topic. For example, I drew some of my information almost math and the hemispheres from the article, "Arithmetics and the brain" by Stanislas Dehaene, Nicolas Molko, Laurent Cohen and Anna J Wilson in the journal Current Opinion in Neurobiology (2004; Volume 14, pages 218-224). For those interested in language, I (with coauthors Edward Wlotko and Aaron Meyer) have written a fairly attainable review called "What's "right" in language comprehension: ERPs reveal right hemisphere linguistic communication capabilities" published in Language and Linguistics Compass (2008; Volume 2, pages 1-17).
You can keep upwardly with more of what Tania Lombrozo is thinking on Twitter: @TaniaLombrozo
Source: https://www.npr.org/sections/13.7/2013/12/02/248089436/the-truth-about-the-left-brain-right-brain-relationship
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