right hemisphere essay

Left Brain vs. Right Brain: Hemisphere Function

Eagle Gamma

Freelance Writer

Eagle Gamma writes about science & technology for the BBC, the US Department of Energy, and popular magazines.

Learn about our Editorial Process

Saul McLeod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

Hemispheric lateralization is the idea that both brain hemispheres are functionally different and that specific mental processes and behaviors are mainly controlled by one hemisphere rather than the other.

Left hemisphere function

The left hemisphere controls the right-hand side of the body and receives information from the right visual field, controlling speech, language, and recognition of words, letters, and numbers.

Right hemisphere function

The right hemisphere controls the left-hand side of the body and receives information from the left visual field, controlling creativity, context, and recognition of faces, places, and objects.

According to the left-brain, right-brain dominance theory, the left side of the brain is considered to be adept at tasks that are considered logical, rational, and calculating.

By contrast, the right side of the brain is best at artistic, creative, and spontaneous tasks (Corballis, 2014; Joseph, 1988).

Brain Lateralization

Brain lateralization has become a somewhat controversial topic. While evidence supports some mental capacity occurring predominantly on one side of the brain or the other, science has overturned several earlier notions relating to this topic.

Psychologists now consider functions like language, spatial processing, and certain broader tasks to have lateralization. Language uses several brain modules, many of which are situated on the left side of the brain (Taylor, 1990).

In fact, language represents one of the main areas of interest for brain lateralization and the function for which this neurological division was first found. Even the language neurons, however, may also be split among both halves of the brain (Riès et al., 2016), or located on the right side, which is more common in left-handed people (Beaumont, 2008).

The left side of the brain often contains language-processing regions such as Broca’s Area , which produces understandable sentences, as well as Wernicke’s area , which understands speech (Griggs, 2010).

Injuries to these areas result in speech pathologies, such as an inability to speak or usually listen (Broca, 1865; Pinel & Barnes, 2017). Other language functions, like associating emotions with phrases, occur on the right side of the brain (Kandel et al., 2012).

As such, language can be seen as bridging together both halves of the brain, but with some specific functionality located on one side or the other (Riès et al., 2016). Scientists have studied language, memory, and other topics through various methods, such as the “Wada test.”

This involves disabling one side of the brain chemically, then observing how the other side operates. Logical thinking, like language, often resides primarily on the left side of the brain (Dehaene, 1999).

Again, this applies more often to right-handed people, with the reverse holding true for many left-handed people. The right brain, by contrast, has more active involvement than the left in visual or spatial processing.

As such, this works while drawing, navigating around a room, or in other comparable situations. People who have right brain injuries may become clumsy or artistically inept (McGilchrist, 2019). The right brain also becomes active while recognizing faces.

As with other functionalities, there is some degree of symmetry. The left brain can also do facial recognition, but it is more perfunctory than the right brain’s work. The right brain deals with other social perception, too, like body posture (Lane & Nadel, 2002).

Another feature of the right brain is to focus one’s attention. When a person thinks about one topic, this lights up regions on the right side of the brain. Numerous other mental activities operate differently on each side of the brain.

For example, the left brain is more associated with positive emotions, while the right brain is more associated with negative emotions (Lane & Nadel, 2002). People with depression often suffer from a disproportionate ratio of right-to-left brain activity (Atchley et al., 2003; Hecht, 2010).

Comparing the left versus right sides of the brain, the left brain processes new information into an understanding of events (making it the “interpreter”), while the right brain accounts for social behaviors.

For example, the left brain may assess which actions would lead to eating food, while the right brain may nix some of these actions on the basis of social norms (one doesn’t just run through a crowd at a party to grab food).

The left brain can be seen as an analyst, breaking apart concepts into smaller, manageable chunks. By contrast, the right brain can be seen as a synthesist, developing a more cohesive view (McGilchrist, 2019).

Interestingly, the lateralization of the brain has deeper roots in the peripheral nervous systems (Craig 2005). Nerves throughout the body feed into and out of the brain.

The left brain largely receives connections from the parasympathetic system, while the right brain largely receives connections from the sympathetic system (Conesa 1995).

Together, the two halves of the brain work with the rest of the nervous system to maintain a homeostatic balance.

The two sides of the brain are connected together by several components called “commissural nerve tracts”, largely the corpus callosum.

This segment bridges the left and right brains, sharing information. In rare cases, people are born without the corpus callosum or have it surgically removed to reduce epileptic seizures.

These cases have revealed interesting information about the two halves of the brain. In people without a corpus callosum, the brain can reorganize to perform functions normally occurring on one side instead of the other.

This may even result in the person developing the use of brain regions on both sides for the same task, allowing, for example, a person to read two texts simultaneously, one on each side of the brain.

The brain can also reorganize itself under other conditions (Gómez-Robles et al., 2013). Often this involves using either a nearby region or a mirror opposite region to replace lost function. This shows how the brain structure has largely symmetrical functionality on the left versus right halves.

There are, however, some slight differences. The body is connected to the brain, so senses as well as control usually take place on the opposite side. The left brain senses and controls the right hand, the right foot, the right half of the visual field, the right ear, and so forth.

Scientists discovered this by electrically probing the brain and observing the body’s responses, which produced a map of the body’s associations in the brain.

The motor cortex produces motions for the opposite side. In right-handed people, the left motor cortex is usually larger than the right motor cortex. Left-handed people, by contrast, often have right-brain dominance.

In addition, some people are ambidextrous (able to use both sides effectively) or have mixed dominance (using the left side for some activities but the right side for others).

The brain evolved to have some asymmetry (Vallortigara & Rogers, 2005), which occurs at multiple levels, from the basic cell arrangements differing on each side to the right hemisphere sitting slightly forward of the left hemisphere (called Yakovlevian torque).

Numerous specific brain regions, like the parietal operculum or the central sulcus, have left-right asymmetry. People who have less brain asymmetry may suffer from less effective thought processes, even schizophrenia or mood disorders (Sun et al., 2015; Ribolsi et al., 2014).

Numerous other disorders also have bases in left-right brain problems (Royer et al., 2015). In one contentious theory, called bicameralism, the left-right human brain evolved only over the last three thousand years or so from having two different identities within it.

One of these minds would speak, issuing commands, while the other mind would listen, obeying. Split-brain patients often act as though they have two minds, which some neuroscientists argue may be the case (called “dual consciousness”).

For example, one side of the body may work to prevent the other side of the body from acting. This would put a more literal spin on the phrase “being of two minds.”

Roger W. Sperry, a twentieth-century neuroscientist, made numerous contributions to the understanding of the twin halves of the brain.

Sperry (1967) conducted investigations on split-brain patients, people whose left and right brains lack the normal connections between them. These people sometimes exhibit brain-side dominance, but they also display a range of distinctive behaviors from only one side or the other.

Sperry also studied animal subjects, rewiring their nervous systems to send signals to the opposite side of the body. This showed how some mental features have hard wiring on one side of the brain while other mental features can adapt to function correctly on either side of the brain.

Sperry’s work revealed that the left side of the brain contains critical modules for producing sentences but that the right side of the brain retains some language capacities, such as understanding the social context of speech. The psychology of left brain versus right brain dominance indicates that humans have brains with overlapping yet distinct halves.

Critical Evaluation

How lateralized are brain functions? Not nearly as much as people often think. While one’s brain lateralization can affect personality, this only has a small part in the overall development of an individual.

People generally use both sides of the brain equally. There are, however, numerous specific brain regions on either the left or right side, which can have powerful effects.

For example, a person who had part of the right prefrontal lobe removed became incapable of valuing long-term rewards over short-term considerations, while people with regions of the left brain removed exhibit different symptoms (Lane & Nadel, 2002).

The two sides of the brain have somewhat different contributions in many ways: how one thinks, how one perceives other people and the environment, how one feels (both consciously and unconsciously), how mentally healthy one is, and countless other facets of personality and behavior.

Left-handed people have right brain dominance for body control, which may also result in the more artistic personality for which such people are known. However, as can be seen by the fact that there are numerous right-handed artists as well as left-handed rational thinkers, brain lateralization only goes so far.

The notion of left-brain versus right-brain dominance has some basis, but it represents a false dichotomy. The complexity of the brain involves features on both sides working together, often communicating with each other through the center (Beaumont, 2008).

Many mental functions require both sides of the brain to work in unison, undermining the claim that either side outdoes the other. As a whole, the brain remains poorly understood, with scientists continuing to investigate (Halpern, 2005).

What we do know about left-brain versus right-brain dominance is that it seems to have specific patterns, such as language or logic often occurring in the left brain or emotion and social cognition often occurring in the right brain.

However, these sides can be reversed in individuals or more balanced between both sides. Also, all of these functionalities have at least some equivalent on the opposite side of the brain.

The brain has plasticity, and in cases such as injury, it will recruit other regions which can easily be located on the opposite side (Pulsifer, 2004).

However, each brain is unique. Some have different lateralization than others, and the location of functions can even develop during the course of one’s life.

What does the right side of the brain control?

The right side of the brain primarily controls spatial abilities, face recognition, visual imagery, music awareness, and artistic skills. It’s also linked to creativity, imagination, and intuition.

However, the concept of each brain hemisphere controlling distinct functions is an oversimplification; both hemispheres work together for most tasks.

What does the left side of the brain control?

The left side of the brain mainly controls logic-related tasks, such as science and mathematics, language processing, like grammar and vocabulary, and fact-based thinking. It’s also involved in analytical abilities and sequential processing.

Nevertheless, the notion of each brain hemisphere controlling distinct tasks is a simplification; in reality, both hemispheres collaborate for most activities.

Atchley, R. A., Ilardi, S. S., & Enloe, A. (2003). Hemispheric asymmetry in the processing of emotional content in word meanings: The effect of current and past depression. Brain and Language, 84 (1), 105–119.

Beaumont, G. J. (2008). Introduction to Neuropsychology (2nd ed.). The Guilford Press.

Broca, P. (1865). Sur le siège de la faculté du langage articulé. Bulletins de La Société d’anthropologie de Paris, 6 (1), 377–393.

Conesa, J. (1995). Electrodermal Palmar Asymmetry and Nostril Dominance. Perceptual and Motor Skills, 80 (1), 211–216.

Corballis, M. C. (2014). Left brain, right brain: facts and fantasies . PLoS Biol, 12 (1), e1001767.

Craig, A. D. B. (2005). Forebrain emotional asymmetry: a neuroanatomical basis? Trends in Cognitive Sciences, 9 (12), 566–571.

Dehaene, S. (1999). Sources of Mathematical Thinking: Behavioral and Brain-Imaging Evidence. Science, 284 (5416), 970–974.

Drew, W. (2020). Psychology . John Wiley & Sons.

Gómez-Robles, A., Hopkins, W. D., & Sherwood, C. C. (2013). Increased morphological asymmetry, evolvability and plasticity in human brain evolution. Proceedings of the Royal Society B: Biological Sciences, 280 (1761), 20130575.

Griggs, R. A. (2010). Psychology: A Concise Introduction (Third ed.). Worth Publishers.

Halpern, M. E. (2005). Lateralization of the Vertebrate Brain: Taking the Side of Model Systems. Journal of Neuroscience, 25 (45), 10351–10357.

Harenski, C. L., & Hamann, S. (2006). Neural correlates of regulating negative emotions related to moral violations. NeuroImage, 30 (1), 313–324.

Hecht, D. (2010). Depression and the hyperactive right-hemisphere. Neuroscience Research, 68 (2), 77–87.

Hines, T. (1987). Left Brain/Right Brain Mythology and Implications for Management and Training. The Academy of Management Review, 12 (4), 600.

Joseph, R. (1988). The right cerebral hemisphere: Emotion, music, visual‐spatial skills, body‐image, dreams, and awareness . Journal of Clinical Psychology, 44 (5), 630-673.

Kandel, E. R., Schwartz, J. H., Jessell, T. M., Siegelbaum, S. A., & Hudspeth, A. J. (2012). Principles of Neural Science, Fifth Edition (Principles of Neural Science (Kandel)) (5th ed.). McGraw-Hill Education / Medical.

Lane, R. D., & Nadel, L. (2002). Cognitive Neuroscience of Emotion (Series in Affective Science). Oxford University Press.

McGilchrist, I. (2019). The Master and His Emissary: The Divided Brain and the Making of the Western World (Second Edition, New Expanded ed.). Yale University Press.

Pinel, J. P. J., & Barnes, S. (2017). Biopsychology (10th Edition) (10th ed.). Pearson.

Pulsifer, M. B., Brandt, J., Salorio, C. F., Vining, E. P. G., Carson, B. S., & Freeman, J. M. (2004). The Cognitive Outcome of Hemispherectomy in 71 Children. Epilepsia, 45 (3), 243–254.

Ribolsi, M., Daskalakis, Z. J., Siracusano, A., & Koch, G. (2014). Abnormal Asymmetry of Brain Connectivity in Schizophrenia. Frontiers in Human Neuroscience, 8 , 1010.

Riès, S. K., Dronkers, N. F., & Knight, R. T. (2016). Choosing words: left hemisphere, right hemisphere, or both? Perspective on the lateralization of word retrieval. Annals of the New York Academy of Sciences, 13 69(1), 111–131.

Royer, C., Delcroix, N., Leroux, E., Alary, M., Razafimandimby, A., Brazo, P., Delamillieure, P., & Dollfus, S. (2015). Functional and structural brain asymmetries in patients with schizophrenia and bipolar disorders. Schizophrenia Research, 161 (2–3), 210–214.

Sun, Y., Chen, Y., Collinson, S. L., Bezerianos, A., & Sim, K. (2015). Reduced Hemispheric Asymmetry of Brain Anatomical Networks Is Linked to Schizophrenia: A Connectome Study. Cerebral Cortex , bhv255.

Taylor, I. (1990). Psycholinguistics: Learning and Using Language (1st ed.). Pearson.

Toga, A. W., & Thompson, P. M. (2003). Mapping brain asymmetry. Nature Reviews Neuroscience, 4 (1), 37–48.

Vallortigara, G., & Rogers, L. (2005). Survival with an asymmetrical brain: advantages and disadvantages of cerebral lateralization. Behavioral and Brain Sciences, 28 (4), 575–589.

Further Reading

• Gainotti, G. (2014). Why are the right and left hemisphere conceptual representations different?. Behavioral neurology, 2014.
• Macdonald, K., Germine, L., Anderson, A., Christodoulou, J., & McGrath, L. M. (2017). Dispelling the myth: Training in education or neuroscience decreases but does not eliminate beliefs in neuromyths. Frontiers in Psychology, 8, 1314.
• Corballis, M. C. (2014). Left brain, right brain: facts and fantasies. PLoS Biol, 12(1), e1001767.
• Nielsen, J. A., Zielinski, B. A., Ferguson, M. A., Lainhart, J. E., & Anderson, J. S. (2013). An evaluation of the left-brain vs. right-brain hypothesis with resting state functional connectivity magnetic resonance imaging. PloS one, 8(8), e71275.

Understanding the Right Brain: Characteristics, Functions, and Dominance

The human brain is a complex and fascinating organ that controls a vast array of physiological and cognitive functions . It is divided into two hemispheres , each with its unique set of functions and characteristics . The left hemisphere is primarily responsible for logical , analytical, and linear thinking , while the right hemisphere is associated with creativity , intuition , and holistic thinking. In recent years, there has been a growing interest in the right brain , with many people wondering what it entails to be a “right-brained” person. In this article, we will explore the characteristics, functions, dominance , and activities associated with the right brain.

What is the Right Brain?

The right brain is the hemisphere of the brain responsible for intuitive, creative, and subjective thinking. Unlike the left hemisphere, which uses language and logical thinking to interpret the world, the right hemisphere processes information holistically, considering all factors and context. The right brain is often associated with emotions , visual and spatial perception, and nonverbal communication.

What Are 3 Characteristics of the Right Brain?

The Right brain is rich in characteristics that distinguish it from the left brain. Here are three of the most notable ones:

Creativity – The right brain is often linked to creativity, and rightly so. This hemisphere of the brain can think outside the box and generate unique solutions to problems. Creative fields such as art, music, and dance are often dominated by right-brained individuals who have a natural talent for coming up with novel ideas.

Intuition – The right brain can process information holistically, taking into account all the factors that influence a situation. As such, it is often linked to intuition, which is the ability to understand something instinctively without the need for conscious reasoning.

Emotional Intelligence – The right brain is more receptive to emotional information than the left brain. It can process nonverbal communication, including body language and facial expressions, and understand the emotions behind them.

What is a Right Brain Person Like?

A right-brained person is often described as creative, intuitive, and emotionally expressive. They tend to be more spontaneous, flexible, and imaginative than their left-brained counterparts. Right-brained individuals are also good at seeing the bigger picture and making connections between seemingly unrelated concepts. They may have a wild imagination and a strong sense of empathy towards others.

Right Brain Dominance

While most people use both hemispheres of their brains equally, some individuals exhibit a greater dominance of one hemisphere over the other. Right-brain dominance means that the right hemisphere is more active and influential than the left hemisphere. According to some studies, 50% of the population may be right-brain dominant. Although most of us possess a dominant hemisphere, it is essential to note that both hemispheres are still involved in all cognitive functions.

What is a Left Brained Person Like?

Left-brained individuals are often logical, analytical, and detail-oriented. They are better at tasks that require language, math, reasoning, and organization. They thrive on facts and figures and can work methodically towards a goal. Left-brained people tend to be linear thinkers and may struggle with creativity, visualization, and holistic thinking.

Right Brain Functions

The right hemisphere of the brain plays a critical role in several cognitive functions:

Creativity – The right brain processes information in a way that allows for the generation of new ideas and concepts.

Emotion – The right brain is more active when it comes to processing emotions, including empathy and social cues.

Visual Perception – The right brain is dominant in visual and spatial perception, which enables us to interpret and navigate the world around us.

Intuition – The right brain processes information holistically, allowing for quick and instinctive decision-making.

Right Brain vs. Left Brain Test

Several tests and quizzes on the internet claim to assess whether you are right or left-brained. However, a study conducted at the University of Utah revealed that the brain patterns of right and left-brained individuals were similar, making these tests unreliable. While there may be differences in the way left and right-brained individuals process information, it is essential to note that both hemispheres work together in various cognitive tasks.

Right Brain Activities

There are several activities that can help stimulate the right hemisphere of the brain and promote creative and intuitive thinking. Here are some of our top picks:

Music – Listening to music can activate several areas of the right brain, promoting creativity and emotional expression.

Art – Engaging in artistic activities, including drawing, painting, and sculpting, can stimulate the right hemisphere of the brain and improve visual-spatial skills.

Mind Mapping – Mind mapping is a visual thinking and note-taking technique that can help improve creativity and critical thinking skills.

Meditation – Meditation is an excellent way to quiet the mind and promote intuitive thinking. It can enhance self-awareness and boost creativity.

What Does Having a Right-Sided Brain Mean?

Having a right-sided brain means that the right hemisphere of your brain is more active and influential in your cognitive functions. This dominance may lead to specific cognitive abilities, including creativity, visual-spatial skills, and emotional intelligence.

In conclusion, the right hemisphere of the brain is responsible for creativity, intuition, and emotional intelligence. While most individuals use both hemispheres of the brain equally, some exhibit a greater dominance of one hemisphere over the other. Right-brained individuals tend to be creative, intuitive, and emotionally expressive. There are several activities that can help stimulate the right hemisphere of the brain, including music, art, and meditation. However, it is essential to note that both hemispheres of the brain are involved in all cognitive functions and work together to process information.

• Search the site GO Please fill out this field.
• Newsletters
• Mental Health

What's the Difference Between Your Left Brain and Right Brain?

• Characteristics

Is One Side More Dominant?

• Brain Health Tips

SDI Productions / Getty Images

Have you ever heard people refer to themselves as “left-brained” or “right-brained?” It's a common belief that people with a left brain are more analytical and logical, while people who favor their right brain tend to be more creative and intuitive. While everyone has certain personality traits influenced by the brain, the theory that people favor one side of their brain is a myth. Regardless of your unique or dominant traits, both sides of your brain are necessary for your overall well-being.  

Characteristics and Functions of Each Side

People traditionally think of the left brain's function as being focused on logic and reason. People who consider themselves left-brained often believe their ability to be logical and objective is related to their left brain being more active than their right. The left hemisphere is responsible for processing language and numbers and is active during critical thinking and reasoning.  

The right side of the brain, however, is responsible for the senses, like vision and hearing, memory , and cognition (thinking).   The right brain may also be more active during creative tasks, which is why people who are naturally more artistic consider themselves right-brained.

In reality, the left and right sides of the brain work together. Consider these examples of language and mathematical analysis.

While the left brain specializes in language, the right brain is involved too. The left side of the brain picks up on the sounds of words, and the right side tunes into the emotional features of words and language. This means that both sides of your brain are active and communicating when you process language or talk with another person.

Most people also think the left brain is responsible for solving math equations. While this is true, the right brain helps with spatial awareness and understanding the value of numbers, making analysis easier to process.  

The brain acts as the command center for the body, and billions of neurons connect both sides. Both sides of the brain actually work together during most tasks and are connected by brain fibers. There is no scientific evidence that one side of the brain is more dominant. Rather, each hemisphere has unique abilities.

Despite this finding, many people still believe one side of their brain is more dominant. One study estimated that up to 68% of adults in the United States believe that people favor one side of their brain or that one side is more dominant. So, where does this myth come from?

The theory originated from the work of psychologist Roger W. Sperry, who studied people who had their corpus callosum surgically cut. The corpus callosum is the brain structure that connects the two hemispheres of the brain. The people being studied had this structure surgically cut as part of their treatment for uncontrolled epilepsy , which causes seizures.  

Sperry determined that each side of the brain had specific functions based on the changes experienced by the study participants. However, the idea that one side of the brain is dominant and entirely responsible for one’s personality and strengths has never been proven.

In general, the left hemisphere controls much of the brain’s language and logic skills, while the right hemisphere controls spatial awareness and visual understanding. Even though one side of the brain may be more active during certain tasks or functions, they are both necessary.

Tips for Boosting Brain Health

Because both sides of your brain are so important to your well-being, it's essential to promote overall brain health and stay sharp, especially as you age. Both sides of your brain may benefit from the following lifestyle approaches:

• Exercise daily: Physical activity has a protective effect on the brain and may boost alertness  
• Eat nutritious foods : Focus on fresh fruits and vegetables, lean proteins, healthy fats, and whole grains to sustain brain power and mental health  
• Rest well: Aim to get seven to eight hours of sleep each night to maintain optimal brain function
• Stay connected: Social support and relationships are essential for brain health, so it's important to maintain healthy relationships and lean on your network  
• Give your brain a workout: Challenging your brain through reading, word games, math problems, or puzzles keeps your brain stimulated and functioning
• Avoid smoking: Quit or avoid smoking tobacco, as excess use can increase your risk of neurological conditions, among other chronic illnesses  

A Quick Review

Several pathways connect the left and right sides (hemispheres) of the brain and work together. In the past, people believed that one side of the brain was more dominant than the other. Left-brained people were considered more objective and logical, while right-brained people were seen as creative, artistic, and intuitive. However, no scientific evidence supports the belief that one side is more important or dominant, as both sides are necessary for most tasks and overall well-being.

von Bartheld CS. Myths and truths about the cellular composition of the human brain: A review of influential concepts . J Chem Neuroanat . 2018;93:2-15. doi:10.1016/j.jchemneu.2017.08.004

Maldonado KA, Alsayouri K. Physiology, brain . In: StatPearls . StatPearls Publishing; 2023.

Salillas E, Benavides-Varela S, Semenza C. The brain lateralization and development of math functions: progress since Sperry, 1974 . Front Hum Neurosci . 2023;17:1288154. doi:10.3389/fnhum.2023.1288154

Corballis MC. Left brain, right brain: facts and fantasies. PLoS Biol. 2014;12(1):e1001767. doi:10.1371/journal.pbio.1001767

Joseph R. The right cerebral hemisphere: emotion, music, visual-spatial skills, body-image, dreams, and awareness. J Clin Psychol. 1988;44(5):630-73.

Wang J, Ma S, Yu P, He X. Evolution of human brain left-right asymmetry: Old genes with new functions . Mol Biol Evol . 2023;40(9):msad181. doi:10.1093/molbev/msad181

Jernigan TL, Stiles J. Construction of the human forebrain . Wiley Interdiscip Rev Cogn Sci . 2017;8(1-2):10.1002/wcs.1409. doi:10.1002/wcs.1409

Nielsen JA, Zielinski BA, Ferguson MA, Lainhart JE, Anderson JS. An evaluation of the left-brain vs. right-brain hypothesis with resting state functional connectivity magnetic resonance imaging . PLoS One . 2013;8(8):e71275. doi:10.1371/journal.pone.0071275

Macdonald K, Germine L, Anderson A, Christodoulou J, McGrath LM. Dispelling the myth: Training in education or neuroscience decreases but does not eliminate beliefs in neuromyths . Front Psychol . 2017;8:1314. doi:10.3389/fpsyg.2017.01314

Hotz I, Deschwanden PF, Mérillat S, Liem F, Kollias S, Jäncke L. Associations of subclinical cerebral small vessel disease and processing speed in non-demented subjects: A 7-year study . NeuroImage: Clinical . 2021;32:102884. doi:10.1016/j.nicl.2021.102884

Tyndall AV, Clark CM, Anderson TJ, Hogan DB, Hill MD, Longman RS, Poulin MJ. Protective effects of exercise on cognition and brain health in older edults . Exerc Sport Sci Rev . 2018;46(4):215-223. doi:10.1249/JES.0000000000000161

Ekstrand B, Scheers N, Rasmussen MK, Young JF, Ross AB, Landberg R. Brain foods - the role of diet in brain performance and health . Nutr Rev . 2021;79(6):693-708. doi:10.1093/nutrit/nuaa091

Sommerlad A, Sabia S, Singh-manoux A, Lewis G, Livingston G. Association of social contact with dementia and cognition: 28-year follow-up of the Whitehall II cohort study . PLoS Med . 2019;16(8):e1002862. doi:10.1371/journal.pmed.1002862

Centers for Disease Control and Prevention. Maintaining your brain health .

Related Articles

July 1, 2009

16 min read

Evolutionary Origins of Your Right and Left Brain

The division of labor by the two cerebral hemispheres—once thought to be uniquely human—predates us by half a billion years. Speech, right-handedness, facial recognition and the processing of spatial relations can be traced to brain asymmetries in early vertebrates

By Peter F. MacNeilage , Lesley J. Rogers & Giorgio Vallortigara

The left hemisphere of the human brain controls language, arguably our greatest mental attribute. It also controls the remarkable dexterity of the human right hand. The right hemisphere is dominant in the control of, among other things, our sense of how objects interrelate in space. Forty years ago the broad scientific consensus held that, in addition to language, right-handedness and the specialization of just one side of the brain for processing spatial relations occur in humans alone. Other animals, it was thought, have no hemispheric specializations of any kind.

Those beliefs fit well with the view that people have a special evolutionary status. Biologists and behavioral scientists generally agreed that right-handedness evolved in our hominid ancestors as they learned to build and use tools, about 2.5 million years ago. Right-handedness was also thought to underlie speech. Perhaps, as the story went, the left hemisphere simply added sign language to its repertoire of skilled manual actions and then converted it to speech. Or perhaps the left brain’s capacity for controlling manual action extended to controlling the vocal apparatus for speech. In either case, speech and language evolved from a relatively recent manual talent for toolmaking. The right hemisphere, meanwhile, was thought to have evolved by default into a center for processing spatial relations, after the left hemisphere became specialized for handedness.

In the past few decades, however, studies of many other animals have shown that their two brain hemispheres also have distinctive roles. Despite those findings, prevailing wisdom continues to hold that people are different. Many investigators still think the recently discovered specializations of the two brain hemispheres in nonhumans are unrelated to the human ones; the hemispheric specializations of humans began with humans.

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing . By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

Here we present evidence for a radically different hypothesis that is gaining support, particularly among biologists. The specialization of each hemisphere in the human brain, we argue, was already present in its basic form when vertebrates emerged about 500 million years ago. We suggest that the more recent specializations of the brain hemispheres, including those of humans, evolved from the original ones by the Darwinian process of descent with modification. (In that process, capabilities relevant to ancient traits are changed or co-opted in the service of other developing traits.) Our hypothesis holds that the left hemisphere of the vertebrate brain was originally specialized for the control of well-established patterns of behavior under ordinary and familiar circumstances. In contrast, the right hemisphere, the primary seat of emotional arousal, was at first specialized for detecting and responding to unexpected stimuli in the environment.

In early vertebrates such a division of labor probably got its start when one or the other hemisphere developed a tendency to take control in particular circumstances. From that simple beginning, we propose, the right hemisphere took primary control in potentially dangerous circumstances that called for a rapid reaction from the animal—detecting a predator nearby, for instance. Otherwise, control passed to the left hemisphere. In other words, the left hemisphere became the seat of self-motivated behavior, sometimes called top-down control. (We stress that self-motivated behavior need not be innate; in fact, it is often learned.) The right hemisphere became the seat of environmentally motivated behavior, or bottom-up control. The processing that directs more specialized behaviors—language, toolmaking, spatial interrelations, facial recognition, and the like—evolved from those two basic controls.

The Left Hemisphere Most of the evidence that supports our hypothesis does not come from direct observation of the brain but rather from observations of behavior that favors one or the other side of the body. In the vertebrate nervous system the connections cross between body and brain—to a large degree, nerves to and from one side of the body are linked to the opposite-side hemisphere of the brain.

Evidence for the first part of our hypothesis—that the vertebrate left hemisphere specializes in controlling routine, internally directed behaviors—has been building for some time. One routine behavior with a rightward bias across many vertebrates is feeding. Fishes, reptiles and toads, for instance, tend to strike at prey on their right side under the guidance of their right eye and left hemisphere. In a variety of bird species—chickens, pigeons, quails and stilts—the right eye is the primary guide for various kinds of food pecking and prey capture. In one instance, such a lateralized feeding preference has apparently led to a lateralized bias in the animal’s external anatomy. The beak of the New Zealand wry-billed plover slopes to the right; that way, the plover’s right eye can guide the beak as the bird seeks food under small river stones.

As for mammals, the feeding behavior of humpback whales is a spectacular example of a lateral feeding preference. Phillip J. Clapham, now at the Alaska Fisheries Science Center in Seattle, and his colleagues discovered that 60 out of 75 whales had abrasions only on the right jaw; the other 15 whales had abrasions only on the left jaw. The findings were clear evidence that whales favor one side of the jaw for food gathering and that “right-jawedness” is by far the norm.

In short, in all vertebrate classes—fishes, reptiles, amphibians, birds and mammals—animals tend to retain what was probably an ancestral bias toward the use of the right side in the routine activity of feeding.

Origins of Right-Handedness What do these findings say about the alleged uniqueness of human right-handedness? Evidence for a right-side bias in birds and whales is intriguing, but it hardly makes a convincing argument against the old belief that right-handedness in humans had no evolutionary precursors. Yet more than a dozen recent studies have now demonstrated a right-handed bias among other primates, our closest evolutionary relatives—clearly suggesting that human right-handedness descended from that of earlier primates. The right-hand preference shows itself in monkeys (baboons, Cebus monkeys and rhesus macaques) as well as in apes, particularly in chimpanzees.

Many of the studies of apes have been done by William D. Hopkins of the Yerkes National Primate Research Center in Atlanta and his colleagues. Hopkins’s group observed right-hand preferences particularly in tasks that involved either coordinating both hands or reaching for food too high to grab without standing upright. For example, experimenters placed honey (a favorite food) inside a short length of plastic pipe and gave the pipe to one of the apes. To get the honey, the ape had to pick up the pipe in one hand and scrape out the honey with one finger of the opposite hand. By a ratio of 2 to 1, the apes preferred to scrape honey out with a finger of the right hand. Similarly, in the reaching experiments, the apes usually grabbed the food they wanted with the right hand.

The Yerkes findings also suggest to us that as early primates evolved to undertake harder and more elaborate tasks for finding food, their handedness preferences became stronger, too. The reason, we suspect, is that performing ever more complex tasks made it increasingly necessary for the control signals from the brain to pass as directly as possible to the more skilled hand. Since the most direct route from the left hemisphere—the hemisphere specialized for routine tasks—to the body follows the body-crossing pathways of the peripheral nerves, the right hand increasingly became the preferred hand among nonhuman primates for performing elaborate, albeit routine, tasks.

Communication and the Left Brain The evolutionary descent of human right-handed dexterity via the modification of ancient feeding behavior in ancestral higher primates now seems very likely. But could feeding behavior also have given rise to the left-brain specialization for language? Actually we do not mean to suggest that this development was direct. Rather we argue that the “language brain” emerged from an intermediate and somewhat less primitive specialization of the left hemisphere—namely, its specialization for routine communication, both vocal and nonvocal. But contrary to long-held beliefs among students of human prehistory, neither of those communicative capabilities first arose with humans; they, too, are descended from hemispheric specializations that first appeared in animals that lived long before our species emerged.

In birds, for instance, studies have shown that the left hemisphere controls singing. In sea lions, dogs and monkeys, the left hemisphere controls the perception of calls by other members of the same species. One of us (Rogers), in collaboration with Michelle A. Hook-Costigan, now at Texas A&M University, observed that common marmosets open the right side of their mouths  wider than the left side when making friendly calls to other marmosets. People also generally open the right side of their mouths to a greater extent than the left when they speak—the result of greater activation of the right side of the face by the left hemisphere.

Little is universal in nature, though, and in some animals a vocal response to highly emotional circumstances has also been linked to the left brain, not—as one might expect—to the right. When a male frog is clasped from behind and held by a rival male, for instance, the left hemisphere seems to control the vocal responses of the first frog. The left hemisphere in mice controls the reception of distress calls from infant mice, and in gerbils it controls the production of calls during copulation. But those animals may be exceptions. In humans and monkeys—and perhaps in most other animals—the right brain takes control in highly emotional vocalizing; the left brain sticks to the routine.

Nonvocal communication in humans has evolutionary antecedents as well. Not only do chimpanzees tend to be right-handed when they manipulate objects, but they also favor the right hand for communicative gestures. Gorillas, too, tend to incorporate the right hand into complex communications that also involve the head and the mouth. Adrien Meguerditchian and Jacques Vauclair, both at the University of Provence in France, have even observed a right-handed bias for one manual communication (patting the ground) in baboons.

The evolutionary significance of all this becomes clear as soon as one notes that humans also tend to make communicative gestures with the right hand. The lateralized behavior we share with baboons suggests that right-handed communications arose with the first appearance of the monkeylike ancestor we share with baboons. That creature emerged perhaps 40 million years ago—well before hominids began to evolve.

Evolution of Speech A fundamental question remains: Just how could any of the behaviors already controlled by the left brain—feeding, vocalizing, communicating with the right hand—have been modified to become speech—one of the most momentous steps in the history of life on earth?

One of us (MacNeilage) has hypothesized that it required the evolution of the syllable, the basic organizational unit underlying a stream of speech in time. The typical syllable is a rhythmic alternation between consonants and vowels. (Consonants are the sounds created when the vocal tract is momentarily closed or almost closed; vowels are the sounds created by resonance with the shape of the vocal tract as air flows relatively freely out through the open mouth.) The syllable may have evolved as a by-product of the alternate raising (consonant) and lowering (vowel) of the mandible, a behavior already well established for chewing, sucking and licking. A series of these mouth cycles, produced as lip smacks, may have begun to serve among early humans as communication signals, just as they do to this day among many other primates.

Somewhat later the vocalizing capabilities of the larynx could have paired with the communicative lip smacks to form spoken syllables. Syllables were perhaps first used to symbolize individual concepts, thus forming words. Subsequently, the ability to form sentences (language) presumably evolved when early humans combined the two kinds of words that carry the main meaning of sentences: those for objects (nouns) and those for actions (verbs).

The Right Hemisphere What about the second half of our hypothesis? How strong is the evidence that, early in vertebrate evolution, the right hemisphere specialized in detecting and responding to unexpected stimuli? In what ways has that underlying specialization evolved and been transformed?

One set of findings that lend strong support to our hypothesis comes from studies of the reactions to predators by various animals. After all, few events in ancient vertebrate environments could have been more unexpected and emotion-laden than the surprise appearance of a deadly predator. Sure enough, fishes, amphibians, birds and mammals all react with greater avoidance to predators seen in the left side of their visual field (right side of the brain) than in their right visual field.

Evidence that the same hemispheric specialization for reactions holds for humans comes from brain-imaging studies. In a summary of those studies, Michael D. Fox and his colleagues at Washington University in St. Louis conclude that humans possess an “attentional system” in the right hemisphere that is particularly sensitive to unexpected and “behaviorally relevant stim­uli”—or in other words, the kind of stimuli that say, in effect, Danger ahead! The existence of such an attentional system helps to make sense of an otherwise inexplicable human propensity: in the laboratory, even right-handed people respond more quickly to unexpected stimuli with their left hand (right hemisphere) than with their right hand.

Even in nonthreatening circumstances, many vertebrates keep a watchful left eye on any visible predators. This early right-hemisphere specialization for wariness in the presence of predators also extends in many animals to aggressive behavior. Toads, chameleons, chicks and baboons are more likely to attack members of their own species to their left than to their right.

In humans the relatively primitive avoidance and wariness behaviors that manifest right-hemisphere attentiveness in nonhuman animals have morphed into a variety of negative emotions. Nineteenth-century physicians noticed that patients complained more often of hysterical limb paralyses on the left side than on the right. There is some evidence for right-hemisphere control of emotional cries and shouts in humans—in striking contrast with the emotionally neutral vocalizations controlled by the left hemisphere. People are more likely to become depressed after damage to the left hemisphere than to the right. And in states of chronic depression the right hemisphere is more active than the left.

Recognizing Others Along with the sudden appearance of a predator, the most salient environmental changes to which early vertebrates had to react quickly were en­counters with others of their own species. In fishes and birds the right hemisphere recognizes social companions and monitors social behavior that might require an immediate reaction. Hence, the role of the right hemisphere in face perception must have descended from abilities of relatively early vertebrates to recognize the visual appearance of other individuals of their species.

For example, only some species of fishes—among the earliest evolving vertebrates—may be able to recognize individual fish, but birds in general do show a right-hemisphere capacity to recognize individual birds. Keith M. Kendrick of the Babraham Institute in Cambridge, England, has shown that sheep can recognize the faces of other sheep (and of people) from memory and that the right hemisphere is preferentially involved. Charles R. Hamilton and Betty A. Vermeire, both at Texas A&M, have observed similar behavior in monkeys.

In humans neuroscientists have recently recognized that the right hemisphere specializes in face recognition. Prosopagnosia, a neurological disorder that impairs that ability, is more often a result of damage to the right hemisphere than to the left. Extending face recognition to what seems another level, both monkeys and humans interpret emotional facial expressions more accurately with the right hemisphere than with the left. We think that this ability is part of an ancient evolutionary capacity of the right hemisphere for determining identity or familiarity—for judging whether a present stimulus, for instance, has been seen or encountered before.

Global and Local We have argued for a basic distinction between the role of the left hemisphere in normal action and the role of the right hemisphere in unusual circumstances. But investigators have highlighted additional dichotomies of hemispheric function as well. In humans the right hemisphere “takes in the whole scene,” attending to the global aspects of its environment rather than focusing on a limited number of features. That capacity gives it substantial advantages in analyzing spatial relations. Memories stored by the right hemisphere tend to be organized and recalled as overall patterns rather than as a series of single items. In contrast, the left hemisphere tends to focus on local aspects of its environment.

Striking evidence for the global-local dichotomy in humans has been brought to light by a task invented by David Navon of the University of Haifa in Israel. Brain-damaged patients are asked to copy a picture in which 20 or so small copies of the uppercase letter A have all been arranged to form the shape of a large capital H. Patients with damage to the left hemisphere often make a simple line drawing of the H with no small A letters included; patients with damage to the right hemisphere scatter small A letters unsystematically all over the page.

A similar dichotomy has been detected in chickens, suggesting its relatively early evolution. Richard J. Andrew of the University of Sussex in England and one of us (Vallortigara) have discovered that, as in humans, the domestic chick pays special attention to broad spatial relations with its right hemisphere. Moreover, chicks with the right eye covered, hence receiving input only to the right hemisphere, show interest in a wide range of stimuli, suggesting they are attending to their global environment. Chicks that can attend only with the left hemisphere (left eye covered) focus only on specific, local landmark features.

Why Do Hemispheres Specialize? Why have vertebrates favored the segregation of certain functions in one or the other half of the brain? To assess an incoming stimulus, an organism must carry out two kinds of analyses simultaneously. It must estimate the overall novelty of the stimulus and take decisive emergency action if needed (right hemisphere). And it must determine whether the stimulus fits some familiar category, so as to make whatever well-established response, if any, is called for (left hemisphere).

To detect novelty, the organism must attend to features that mark an experience as unique. Spatial perception calls for virtually that same kind of “nose for novelty,” because almost any standpoint an animal adopts results in a new configuration of stimuli. That is the function of the right hemisphere. In contrast, to categorize an experience, the organism must recognize which of its features are recurring, while ignoring or discarding its unique or idiosyncratic ones. The result is selective attention, one of the brain’s most important capabilities. That is the function of the left hemisphere.

Perhaps, then, those hemispheric specializations initially evolved because collectively they do a more efficient job of processing both kinds of information at the same time than a brain without such specialized systems. To test this idea, we had to compare the abilities of animals having lateralized brains with animals of the same species having nonlateralized brains. If our idea was correct, those with lateralized brains would be able to perform parallel functions of the left and right hemisphere more efficiently than those with nonlateralized brains.

Fortunately, one of us (Rogers) had already shown that by exposing the embryo of a domestic chick to light or to dark before hatching, she could manipulate the development of hemispheric specialization for certain functions. Just before hatching, the chick embryo’s head is naturally turned so that the left eye is covered by the body and only the right eye can be stimulated by light passing through the egg shell. The light triggers some of the hemispheric specializations for visual processing to develop. By incubating eggs in the dark, Rogers could prevent the specializations from developing. In particular, she found, the dark treatment prevents the left hemisphere from developing its normal superior ability to sort food grains from small pebbles, and it also prevents the right hemisphere from being more responsive than the left to predators.

Rogers and Vallortigara, in collaboration with Paolo Zucca of the University of Teramo in Italy, tested both kinds of chicks on a dual task: the chicks had to find food grains scattered among pebbles while they monitored for the appearance of a model predator overhead. The chicks incubated in light could perform both tasks simultaneously; those incubated in the dark could not—thereby confirming that a lateralized brain is a more efficient processor.

Social “Symmetry Breaking” Enabling separate and parallel processing to take place in the two hemispheres may increase brain efficiency, but it does not explain why, within a species, one or the other specialization tends to predominate. Why, in most animals, is the left eye (and the right hemisphere) better suited than the right eye (and the left hemisphere) for vigilance against predation? What makes the predominance of one kind of handedness more likely than a symmetric, 50–50 mixture of both?

From an evolutionary standpoint a “broken” symmetry, in which populations are made up mainly of left types or mainly of right types, could be disadvantageous because the behavior of individuals would be more predictable to predators. Predators could learn to approach on the prey’s less vigilant side, thereby reducing the chance of being detected. The uneven proportion of left- and right-type individuals in many populations thus indicates that the imbalance must be so valuable that it persists despite the increased vulnerability to predators. Rogers and Vallortigara have suggested that, among social animals, the advantage of conformity may lie in knowing what to expect from others of one’s own species.

Together with Stefano Ghirlanda of the Universities of Stockholm in Sweden and of Bologna in Italy, Vallortigara recently showed mathe­matically that populations dominated by left-type or by right-type individuals can indeed arise spontaneously if such a population has frequency-dependent costs and benefits. The mathematical theory of games often shows that the best course of action for an individual may depend on what most other members of its own group decide to do. Applying game theory, Ghirlanda and Vallortigara demonstrated that left- or right-type behavior can evolve in a population under social selection pressures—that is, when asymmetrical individuals must coordinate with others of their species. For example, one would expect schooling fish to have evolved mostly uniform turning preferences, the better to remain together as a school. Solitary fish, in contrast, would probably vary randomly in their turning preferences, because they have little need to swim together. This is in fact the case.

With the realization that the asymmetrical brain is not specific to humans, new questions about a number of higher human functions arise: What are the relative roles of the left and right hemispheres in having self-awareness, consciousness, empathy or the capacity to have flashes of insight? Little is known about those issues. But the findings we have detailed suggest that these functions—like the other human phenomena discussed here—will be best understood in terms of the descent with modification of prehuman capabilities.

Did the Syllable Evolve from Chewing? According to one of the authors (MacNeilage), the origin of human speech may be traceable to the evolution of the syllable—typically an alternation between consonant and vowel. In the word “mama,” for instance, each syllable begins with the consonant sound [m] and ends with the vowel sound [a]. As the cutaway diagrams show, the [m] sound is made by temporarily raising the jaw, or lower mandible, and stopping the flow of air from the lungs by closing the lips (below left). To make the following vowel sound [a], the jaw drops and air flows freely through the vocal tract (below right). MacNeilage has thus proposed that the making of syllabic utterances is an evolutionary modification of routine chewing behavior, which first evolved in mammals 200 million years ago.

A Lateralized Brain Is More Efficient One of the authors (Rogers) discovered that if she exposed chick embryos to light or to dark before they hatched, she could control whether the two halves of the chick brains developed their specializations for visual processing—that is, whether the chicks hatched with weakly or strongly lateralized brains. Rogers and another one of the authors (Vallortigara), with Paolo Zucca of the University of Teramo in Italy, then compared normal, strongly lateralized chicks with weakly lateralized chicks on two tasks. One task was to sort food grains from small pebbles (usually a job for the left hemisphere); the other task was to respond to a model of a predator (a cutout in the shape of a hawk) that was passed over the chicks (usually a task for the right hemisphere). The weakly lateralized chicks had no trouble learning to tell grains from pebbles when no model hawk was present. But when the hawk “flew” overhead, they frequently failed to detect it, and they were much slower than normal chicks in learning to peck at grains instead of pebbles. In short, without the lateral specializations of their brain, the chicks could not attend to two tasks simultaneously.

Note: This article was originally printed with the title, "Origins of the Left and Right Brain."

• Essay #5 Yin/Yang & the Hemispheres of the Brain

“A spiral, folding within itself….”

Light and dark submerging within and emerging from out of each other…., unconscious and conscious thoughts, feelings, urges interweaving…..

The Yin/Yang symbol of the Tao, one of the most enduring in the perennial philosophy, is a great diving off point for contemplating a shift in emphasis to the right hemisphere of our brains in order to regain our emotional/psychological/spiritual balance here in the 21 st century.

Soon after choosing philosophy as my college major, I encountered this symbol for the first time while browsing in a college book store. Over 50 years later, I’m still mesmerized by both its simplicity and complexity all at once.

On the “explicate” level, it’s relatively simple:  black and white sections of a circle divided evenly by a spiral, a white dot within the black, a black dot within the white.

But the deeper “implicit” levels are what stopped me in my tracks (although I had no reason why)  and are the powerful magnetic pull that has made it one of the most enduring symbols in human evolution.

As brought up in previous essays, the left hemisphere of our brains is skilled at breaking things down into smaller parts and analyzing how they are put together (explicit).  The right hemisphere is wired to get a bigger picture or deeper “implicit” meaning which often can’t be best explained in words, but understood at an intuitively felt level.

A common phrase used to define what the yin/yang symbol represents is “Unity of opposites.”  On the explicate level, the black and white sections can be perceived as two opposing forces.  On the implicate level, according to many Taoist accounts, the opposing forces are generated from an underlying, unseen unity/harmony.

So, at the explicate level, yin/yang can reflect a constant pattern of conflict, opposition and competition. From the perspective of the right hemisphere, as taught through the millennia by more intuitive philosophers and spiritual sages, the spiral within the circle reflects a continuous flow between the black and the white which co-exist in an underlying harmony.

Diving into the Spiraling Wave

As with many explorations of ancient Asian wisdom, I turn to one of the most gifted teachers at evoking this wisdom and applying it to our modern age:  Alan Watts .

He once stated:

“The yin/yang symbol is a spiral folding within itself.”

With this perspective, let’s dive in.

Often a good place to start when exercising right hemisphere modes of perception is a teaching tale.  Here is one of the most famous Taoist stories, as written in Alan Watts’ book Tao:  The Watercourse Way :

“There was a farmer whose horse ran away. That evening the neighbors gathered to commiserate with him since this was such bad luck. He said, “May be.” The next day the horse returned, but brought with it six wild horses, and the neighbors came exclaiming at his good fortune. He said, “May be.” And then, the following day, his son tried to saddle and ride one of the wild horses, was thrown, and broke his leg. Again, the neighbors came to offer their sympathy for the misfortune. He said, “May be.” The day after that, conscription officers came to the village to seize young men for the army, but because of the broken leg the farmer’s son was rejected. When the neighbors came in to say how fortunately everything had turned out, he said, “May be.”   

You can hear Alan Watts talking about yin/yang here.

He comments on the fact that the symbol contains a white dot in the black pattern and a black dot in the white pattern:

“Obviously black and white are as different as different can be…but strangely black is white in a strange sense. And white is black…because black implies white and white implies black. All positive implies negative and negative implies positive. Because you can’t have the one without the other. To put this into clear words we can say explicatively, black and white are different. But implicitly…they are one. So outwardly, the positive and negative of life are very different.  Life is different from death and good is different from evil. But esoterically, secretively, they are one.” “Thus, rather than seeing nature as a conquest between opposing forces, the cold vs the heat, the light vs the dark, the day vs the night, man vs woman, the principle of the Yin-Yang is that of mutually-arising. That is to say, to adopt an organic view of nature and appreciate the underlying unity behind the apparent duality. To demonstrate cooperation and harmony in all the various phenomena of nature.”

Nature’s Expression of Yin/Yang

Contemplating down to an individual atom, the building block of nature, we find the unity underlying the apparent opposition: Each atom contains a proton with a positive charge and electrons with negative charge.

At its core, nature generates symmetry through opposites attracting and like repelling.

In the plant world, we easily get entranced by the beauty of the flowers and the trunk, branches and leaves of a tree reaching up towards the sunlight. But that is only half the story.

As beautiful as these photos are, they leave out ½ of the whole picture…As if being captivated by the white section of the yin/yang symbol, being blind to the dark section.

The missing part?  The roots pushing deep into the dark muck of the earth for sustenance, without which the trees we see in the above photographs couldn’t exist, a vivid example of the “explicit” (left hemisphere) being overemphasized to such a degree that the “implicit” roots of life are forgotten.

And science is now telling us that at the “root” level, trees communicate with each in life-enhancing ways. As described in the article published by Smithsonian Magazine, “Do Trees Talk to Each Other?” based on observations by German forester Peter Wohlleben,

“A revolution has been taking place in the scientific understanding of trees, and Wohlleben is the first writer to convey its amazements to a general audience. The latest scientific studies, conducted at well-respected universities in Germany and around the world, confirm what he has long suspected from close observation in this forest: Trees are far more alert, social, sophisticated—and even intelligent—than we thought…”

The article goes on to confirm a significant understanding of evolution:

“Since Darwin, we have generally thought of trees as striving, disconnected loners, competing for water, nutrients and sunlight, with the winners shading out the losers and sucking them dry. The timber industry in particular sees forests as wood-producing systems and battlegrounds for survival of the fittest. There is now a substantial body of scientific evidence that refutes that idea. It shows instead that trees of the same species are communal…These soaring columns of living wood draw the eye upward to their outspreading crowns, but the real action is taking place underground, just a few inches below our feet. “Some are calling it the ‘wood-wide web,’ says Wohlleben.”

The “wood-wide web” clearly includes both underground at the root level as well above ground.

At the same time evidence such as the “wood-wide web,” as detailed in the Smithsonian Magazine article, reveals nature is much more collaborative than competitive, culturally we are still stuck in the constrained paradigm that evolution is based on a ‘survival of the fittest’ based on material gains and competition. The yin/yang symbol reflects the need for collaborative harmony, not getting stuck in the explicate at the cost of missing the implicate.

Wave Theory

At the deep, implicit level of what many ancient Asian sages were tuned into, Yin and Yang, dark and light, can’t be well understood taken separately.  As Alan Watts pointed out, the spiral which visually separates them in the symbol is “folding in on itself.”  So, if we imagine the symbol in motion, the black and white sections would be submerging into and emerging out of each other, understandable only as a ‘mutual whole.’

There is another powerful example we’ve all shared that can tune into a deeper understanding of this underlying ‘mutual whole’………. Watching waves rise and fall as they approach the shoreline.

On the visual, explicit level, we can distinguish one wave from another as they rise out of the surface.  Each wave is clearly separate from the others.  But are they?

It’s virtually impossible to accurately measure where an individual wave begins and ends. For at the moment of the measurement, the wave has shifted its position from the ocean out of which it emerges.  And while at the explicit level, we can see general dimensions as the wave rises and falls, did the visual wave ever fully separate itself from the ocean as a whole?

It can’t.  For beneath the surface of the water each wave is being shaped and formed by the underlying tidal forces not just locally, but throughout the entire undersea tidal dynamics of the ocean at large.

So, at the same time a surfer can choose to ride one particular wave over another and we can distinguish each wave from others, in reality each wave is intricately woven into the expansive push/pull currents of the entire ocean.

The importance of understanding the deeper dynamic of wave/ocean is noted by Alan Watts:

“This (the yin/yang symbol) implies that the art of life is more like navigation than warfare, for what is important is to understand the winds, the tides, the currents, the seasons, and the principles of growth and decay, so that one’s actions may use them and not fight them. At the very roots of ancient Chinese thinking and feeling there lies the principle of polarity, which is not to be confused with the ideas of opposition or conflict. In the metaphors of other cultures, light is at war with darkness, life with death, good with evil, and the positive with the negative, and thus an idealism to cultivate the former and be rid of the latter flourishes throughout much of the world.”

Riding the Quantum Wave

As previously mentioned, the ancient yin/yang symbol is one of the keystones of the perennial philosophy, those transcendent insights that continue to spark the continuing search for deep, edifying patterns of existence.  While primarily an insight in philosophy and spiritual teachings, the yin/yang symbol has influenced science as well.

Niels Bohr, the Nobel Prize-winning scientist whose institute in Copenhagen was the main center for development of quantum physics, was offered a Danish knighthood in 1947. One of the perks was the opportunity to construct a personal coat of arms.  Bohr chose as its central image:  The yin/yang symbol.

This is quite interesting to our topic since it was Bohr who created the most enduring philosophical interpretation of the mysterious contradictions inherent in quantum physics.  Despite the fact that quantum physics is the most successful scientific theory ever (responsible for the current computer driven digital age), at its core, confirmed by multiple experiments, is the bizarre mystery that at the subatomic level an entity such as a photon (which makes up light) or an electron (which makes up electricity)  can be either a particle or a wave, depending on how the experiment is set up.

This makes no logical sense.  A particle has finite, discernible boundaries–a wave is diffused and has no clear boundaries.  How could anything be neither definitively one or the other, but potentially either one?

As physicist David Harrison describes the mystery of Wave/particle duality and Bohr’s philosophical vision called “complementarity:” 

“We can think of an electron as a wave or we can think of an electron as a particle, but we cannot think of it as both at once. But in some sense the electron is both at once. Being able to think of these two viewpoints at once is in some sense being able to understand Quantum Mechanics.”

To think of “two viewpoints at once” connects beautifully to Buddhist teacher Robert Thurman’s statement, cited previously on this website:

“Wisdom is tolerance of cognitive dissonance.”  

In other words, by holding the opposing viewpoints of Wave/particle duality, or for that matter, the dark and light characteristics of yin/yang in the mind, rather than choosing or defaulting to one or the another, we get a fuller sense of how life operates.

No wonder one of the greatest scientists of the 20 th century, Niels Bohr, chose the yin/yang symbol for his coat of arms honor. He was adopting the symbols inherent call:  To understand that what appear to be opposing forces (Wave/particle duality) are, at the deeper level of reality, reflections of an unseen, unified flow.

Note:  During the development of quantum physics, its most brilliant creators, Bohr, Einstein, Heisenberg, Schrodinger, Dirac, Planck, et al, devoted energetic conversation to the mysterious, esoteric philosophical revelations of the quantum world as well as the practical, observable, provable results.  But as is all too common in the Western mind by the 1950’s, the next generation of quantum physicists consciously discarded philosophizing about the deeper meaning of quantum reality (right-hemisphere) to focus entirely on achieving practical advances in quantum technology (left-hemisphere).  This left-hemisphere mind-set to forget about deep meaning and focus on practical results was captured in a quote attributed to physicist David Mermin, which became the operating mantra:

“Shut Up and Calculate!”

(The right-hemisphere might counter with ‘Open Up and Contemplate.’)

While admiring and enjoying the benefits of this left-hemisphere focus (personal computers, laser medical devices, smartphones), we can at the same time point to the crucial human need for deeper meaning and existential insight. (Fortunately, this has always re-surfaced on occasion, examples being Fritz Capra’s brilliant integration of quantum physics and ancient Asian mysticism, “The Tao of Physics” , Quantum physicist David Bohm, Einstein’s protégé, whose contemplation of underlying  unity inspired his 1980  book “Wholeness and the Implicate Order”  and, in the 21 st century, the Nobel-Prize winning theoretical physicist Frank Wilczek who wrote:

“ My 10th key to reality, which emerges from but in some ways transcends science, turned out to be ‘Complementarity is Mind-Expanding.’ Complementarity is an attitude toward life that I’ve found eye-opening and extremely helpful. It has, literally, changed my mind. Through it, I’ve become larger: more open to imagination, and more tolerant.”

Brain Patterns & Flow

We’ve all been in that wonderful, great-feeling, highly productive brain state of “flow,” where linear time seems to disappear and we move effortlessly towards a successful goal.  It’s been commented on by artists, athletes, writers, scientists, musicians and business leaders.

The ancient “spiraling within itself” image of yin and yang clearly reflect a flow inherent in the world and now modern science can explain some of flow’s origins in our brains.

An article on Peak Performance published in TIME Magazine stated,

“Over the past decade, scientists have made enormous progress on flow. Advancements in brain imaging technologies have allowed us to apply serious metrics where once was only subjective experience…

The state emerges from a radical alteration in normal brain function. In flow, as attention heightens, the slower and energy-expensive extrinsic system (conscious processing) is swapped out for the far faster and more efficient processing of the subconscious, intrinsic system.”

The quoted material above is packed with interesting allusions to right-hemisphere wiring:

• On the one hand, it points to “being in flow” as requiring a shift from “extrinsic system” qualities more associated with left-hemisphere thinking towards the “processing of the subconscious, intrinsic system,” more associated with right-hemisphere thinking.
• When we are ‘in the flow state’ our brain doesn’t slow down to break down and analyze different strategies (left-hemisphere characteristic). As the article states, when we are “in flow, the result is liberation [from second guessing]. We act without hesitation. Creativity becomes more free-flowing, risk taking becomes less frightening, and the combination lets us flow at a far faster clip” (right-hemisphere characteristics).

The article then describes the shift in brain wave states which induce this experience:

“In flow, we shift from the fast-moving beta wave of waking consciousness down to the far slower borderline between alpha and theta. Alpha is day-dreaming mode—when we slip from idea to idea without much internal resistance. Theta, meanwhile, only shows up during REM or just before we fall asleep, in that hypnogogic gap where ideas combine in truly radical ways.”

The “day dreaming” alpha wave mode and even deeper theta wave mode are much more effectively processed by the right hemisphere’s openness to totally novel, boundary-shaking messages from the subconscious than the left hemisphere’s predilection for more objective, familiar language.

(Note: As for the even deeper theta brain wave state, I address this in the next Essay:  The Creative Power of Dreams)

As Dr. Iain McGilchrist writes in “The Master and his Emissary:  The Divided Brain and the Making of the Western World,”

the book which is a major influence on this Right Brain Network website:

“ So, the left hemisphere needs certainty and needs to be right. The right hemisphere makes it possible to hold several ambiguous possibilities in suspension together without premature closure on one outcome.” 

This insight is connected on a deep level to Robert Thurman’s, previously mentioned:

“Wisdom is the tolerance of cognitive dissonance.”

Note: Robert Thurman and Iain McGilchrist were the first two guests on our webinar series “What Are We Thinking?  A Trip into the Right Hemisphere of the Human Brain.”

As we encounter the challenge of the sped up, digitalized, globalized, network-connected 21 st century, slowing down our brain waves from the hyperactive beta state to the more reflective, intuitive, open-minded right-hemisphere feels like a much-needed shift.

And if we see the yin/yang symbol as a metaphor for our brain, it can be imagined as pointing to the need for whole-brain thinking, with the two hemispheres working more in concert.  Given the well-researched, well thought-out premise of Iain McGilchrist’s “The Master and his Emissary:  “The Divided Brain and the Making of the Western World:” Western culture has been dominated for centuries by the overly self-assured, technologically oriented left hemisphere, then to achieve whole brain thinking requires a re-balancing shift to a more right hemisphere perception of the deep, powerful patterns of change occurring under the surface of the anxiety-producing 24-hour news cycle.

The yin/yang symbol, apparent oppositions folding in and out of one another, reflecting an implicit Flow & Unity underneath, is much more capable of being felt and understood in the right-hemisphere of our brains’ ability to tune into the alpha and theta brain wave frequencies, to intuit the Whole and not just the parts, to understand collaboration has a greater presence in nature than does competition, to see beyond materialism to the deeper, more pervasive non-material pattern of existence.

Enjoy exploring this week’s quotes and links:

“At heart, science is the quest for awesome – the literal awe that you feel when you understand something profound for the first time. It’s a feeling we are all born with, although it often gets lost as we grow up and more mundane concerns take over our lives.”

― Sean Carroll,  Theoretical Physicist

“The materialistic consciousness of our culture … is the root cause of the global crisis; it is not our business ethics, our politics or even our personal lifestyles. These are symptoms of a deeper underlying problem. Our whole civilization is unsustainable. And the reason that it is unsustainable is that our value system, the consciousness with which we approach the world, is an unsustainable mode of consciousness.”

―  Peter Russell, author, “The Global Brain”

“Dialogue is a space where we may see the assumptions which lay beneath the surface of our thoughts, assumptions which drive us, assumptions around which we build organizations, create economies, form nations and religions. These assumptions become habitual, mental habits that drive us, confuse us and prevent our responding intelligently to the challenges we face every day. “

— David Bohm, Quantum Physicist/Philosopher

• Essay #8: The Creative Power of Dreams
• Essay #7: Global Brain Emerging?
• Essay #6: Gaia Vision
• Essay #4: Where is Evolution Pointing its Finger?
• Essay #3: What’s the Story?
• Essay #2: Synaptic Jumps / Quantum Leaps?
• Essay #1: Signs of the Next Renaissance?
• Right Brain Links of Interest
• Mission Statement