Neuromyth 6

 

The left brain/ right brain myth

Are you a creative and emotional person? Maybe an artist or a musician? Then you are probably right-brained. No? Perhaps you are a rational, analytical and logical thinker? Maybe a mathematician or an engineer? Then you are most likely left-brained. Who does not know that creativity and emotion are located in the right half of the brain, while rationality and logic are situated in the left half of the brain? Everyone has come across this popular notion of left or right brain dominance, which determines a person’s way of thinking and his/her personality. This notion, however, is a widely held misconception. Here we will discuss the concept of this notion, known as hemisphericity or hemispheric dominance, how it arose, and why it is a misconception.

Two parts of the brain: two ways of thinking? Two different kinds of personality?

The concept of hemispheric dominance ascribes different information processing characteristics of to one or the other of the two brain hemispheres (see Table 1). It is concluded, therefore, that the dominant use of either the left or the right hemisphere determines a person’s way of thinking and personality.

According to the ascribed characteristics, the left brain is the rational, intellectual, logical, analytical and verbal hemisphere. It is the hemisphere that specialises in processing verbal and numerical information in a deductive or logical way. It is the hemisphere that specialises in processing verbal and numerical information based on a deductive or logical way of thinking. This means the left hemisphere dissects information by analysing and distinguishing the single parts of the whole. Thereby it processes the information sequentially in a linear and ordered manner.
 Thus, it is asserted that the left hemisphere has a bias for detailed information, is very capable of analysing and structuring information, and is best suited for tasks that comprise language, reading and writing, algebra, mathematical problems, logic operations, and the processing of serial sequences of information. Based on these thinking and problem solving attributes of the left hemisphere, the concept of hemispheric dominance asserts that people who predominantly use the left part of their brain are rational, intellectual, detail oriented, logical and analytical. That means that these people do well in tasks that require these abilities, such as mathematics, engineering or natural sciences.

In contrast to the left brain’s analytical way of thinking, the right brain has attributed to it an intuitive, emotional, holistic, synthesising, non-verbal, visuo-spatial mode of processing, resulting in a creative or inductive way of thinking. Thus, the right hemisphere lumps together information and processes it as a whole and in parallel, i.e. it sees the forest rather than the trees. It is supposed to deal in three-dimensional forms and images with a focus on similarities rather than differences, and so is seen as being strong in tasks that require the understanding of complex configurations and patterns and the simultaneous processing of diverse information like pattern recognition, face recognition or spatial relationships. Due to these characteristics, people who predominantly use their right brain are considered as being artistic, intuitive, emotional, imaginative and visually oriented. These people are strong in tasks that require synthesising and conceptualising abilities and hence are said to be good at gathering, assembling, comparing and reshuffling ideas in order to come up with new concepts. Furthermore, it is asserted that they have a strongly developed emotional and aesthetic sensitivity and often follow creative and artistic professions.

Table 1. Postulated characteristics of the two halves of the brain

Left hemisphere

Right hemisphere

 

 

Verbal

Non-verbal, Visuo-spatial

 

 

Sequential

Simultaneous

 

 

Logical 

Holistic

Analytical 

Synthesising, Integrating

 

 

Rational, Intellectual

Intuitive, Emotional

 

 

The concept of hemisphericity in learning and education

According to the concept of hemisphericity, information is processed in different ways in the two brain hemispheres. It further states that the dominant brain hemisphere determines the way of processing. On the basis of this notion, the idea developed that the learning and thinking process could be enhanced when both sides of the brain participated in a balanced manner. Consequently, teaching and education programs were developed in order to strengthen the less dominant hemisphere of the brain and to synchronise the two hemispheres. Since it is assumed that schools generally favour left-brained ways of thinking and learning, such as analysis, logic and accuracy, many teaching instruction techniques seek to include more right-brained activities. One example of such a whole-brained instruction method is “show and tell”: instead of only reading a “left-brained” text, the teacher also shows pictures and graphics in order to activate the right hemisphere. Other methods include the use of music, metaphors, role plays, meditation, drawing, etc. in order to achieve the synchronisation of the two hemispheres. A general outline of the teaching and problem solving styles of the two hemispheres is given in Table 2. While such methods could be valuable in the educational setting, they are based on a shaky foundation. The reduction of the two sides of the brain to mere seats of certain skills or qualities and the application of this to education, are based on oversimplifications of tendencies that the brain exhibits. These will be more thoroughly explained under the following point.

Table 2. Problem solving skills and related teaching styles incorrectly attributed to the two brain hemispheres

Left brain

Right brain

  • Rational
  • Looks at differences
  • Solves problems by logically and sequentially looking at the parts of things
  • planned and structured

 

  • Emotional, intuitive
  • Looks at similarities
  • Solves problems with hunches, by looking for patterns and configurations
  • fluid and spontaneous

 

Teaching style

  • verbal instructions
  • talking and writing
  • multiple choice tests

 

Teaching style

  • demonstrated instructions
  • drawing and manipulating objects
  • Prefers open ended questions

 

The origin of hemisphericity

Throughout history, the intellectual skills of humans were often divided up into two classes: critical and analytic skills as opposed to creative and synthesising skills. This idea was attributed to the two brain hemispheres and became a major doctrine in neurophysiology in the 19th century. In 1844, Arthur Ladbroke Wigan published a book entitled “A New View of Insanity: Duality of the Mind”. In this book, he describes the two brain hemispheres as independent parts having an independent will and way of thinking. Usually they work together, but in the case of a disease, for example, they might work against each other. This notion became very popular and even found its way into popular culture as with Robert Louis Stevenson’s famous story “The strange case of Dr. Jekyll and Mr. Hyde” (1886), which explores the idea of a cultured left hemisphere in contrast to an emotional right hemisphere, that is primitive and easily out of control.

Language lateralisation and hemispheric dominance of the left hemisphere

Pierre Paul Broca, a French neurologist, was the first to come up with empirical evidence supporting the localisation of different functions in the two hemispheres. Between 1861 and 1863, Broca examined the brains of more than 20 patients with compromised language function after they had died. In all patients, he found there was damage to the left frontal hemisphere, while the right hemisphere was undamaged. He concluded from his observations that speech production is localised in the frontal part of the left brain hemisphere. A few years later, Wernicke, a German neurologist, extended Broca’s view of language localisation. Like Broca, he examined the brains of individuals who had language development impairments. Based on these post-mortem correlations, Wernicke suggested that the ability to comprehend language is located in the temporal lobe of the left hemisphere. Broca and Wernicke both ascribed the comprehension and the production of language, the major determinants of language, to the left hemisphere.

Until the 1960s, observations about language lateralisation were primarily based on post-mortem studies of patients with brain damage of variable location, severity and aetiology. Critics argued that language function might not be lateralised at all. However, definite evidence for language lateralisation arose from studies in split brain patients. In these patients, the nerve fibres that connect the two hemispheres were severed in order to stop the spread of epileptic seizures from one hemisphere to the other. As a result, investigators could study the function of each half of the brain in isolation from the other. The pioneering studies of these split brain patients were carried out in the 1960s and 1970s by the Nobel Prize laureate Roger Sperry and his colleagues at the Californian Institute of Technology. These provided further experimental evidence on hemispheric specialisation in terms of language lateralisation and the localisation of other skills. In order to assess possible functional differences, Roger Sperry and his colleagues provided information only to one side of the brain in split brain patients, such as asking the patients to use each hand independently for the identification of objects without looking at the object. To understand this procedure, it is important to know that the basic sensory and motor functions are symmetrically divided between the two brain hemispheres: the left hemisphere processes information for the right half of the body and vice versa. Thus, the right hand provides the left hemisphere with information about what it feels. Sperry’s experiments yielded an amazing result: when split brain patients processed an object with their right hand, i.e. with their left hemisphere, they could easily name the object. In contrast, when an object was touched with the left hand, i.e. processed by the right hemisphere, they could not name it! This finding put an end to the century long discussion on language lateralisation. It affirmed that the left hemisphere is unequivocally the seat of the major language functions in most individuals.

This unequal representation of language functions in the two hemispheres gave rise to the idea that the left hemisphere is the verbal one, while the right hemisphere is the non-verbal one (see Table 1). Since language has often been regarded as the highest cognitive human achievement, the finding of the hemispheric lateralisation of language further laid the foundation for the misleading concept that one brain hemisphere is “dominant” over the other; namely the left hemisphere, which is the seat of the major capacity for language. In 1868, John Hughlings Jackson, a British neurologist, described this concept of a dominant hemisphere as follows: “Both brains cannot only be duplicates, if damage to only one hemisphere leaves a person speechless. For the processes of language, which are the highest processes possible, there must be one leading side. And in most people, the left brain hemisphere – the side of the will – is the leading one, while the right hemisphere is the automatic one.”

Visuo-spatial and emotional preponderance of the right hemisphere

Other experiments with split brain patients investigated the role of the right hemisphere. The results of these experiments were that the right hemisphere is specialised in processing complex visual and spatial conditions. A video by Sperry and Gazzaniga about the split-brain patient W.J. shows one of the most impressive demonstrations of the superiority of the right hemisphere for visuo-spatial tasks: the patient was given several dice, each with two red sides, two white sides and two sides diagonally separated into white and red stripes. The task of the patient was to arrange the dice according to patterns presented on cards. The beginning of the video shows that W.J. quickly arranges the dice in the required pattern using his left hand (right hemisphere). However, he has great difficulty completing the same task using his right hand. He is slowly and indecisively moving the dice around, when his left hand starts to help and quickly starts to arrange the dice correctly. The investigator draws W.J’s left hand slowly away and again W.J. is lost using only his right hand, moving the dice around unsystematically. This video, as well as other studies by Roger Sperry, clearly show the preponderance of the right hemisphere in processing visuo-spatial stimuli. This role of the right hemisphere is further corroborated with clinical case studies. Patients with certain damage to the right hemisphere are unable to recognise familiar faces (prosopagnosia). Other patients with right hemispheric damage have difficulties in spatial orientation.
 Furthermore, clinical studies let researchers postulate that the right hemisphere is specialised in emotion processing. Emotional expression, as well as emotional recognition and discrimination, are impaired after lesions to the right brain hemisphere: patients with right hemispheric lesions show deficits in identifying the emotional intonation (prosody) of words. In addition, deficits in recognition of emotional facial expression have been linked to lesions of the right hemisphere. These clinical findings are supported by behavioural studies: prosody (emotional speech characteristics) is more easily recognised when stimuli are presented to the left ear (right hemisphere). Furthermore, stimuli presented to the left visual field (right hemisphere) are judged to be more emotional and even to elicit stronger responses from the autonomic nervous system.

Sequential and simultaneous processing in the two hemispheres

By now, we know upon which findings the characteristic “verbal for the left hemisphere, and non-verbal, but visuo-spatial and emotional for the right hemisphere” are based. The next characteristic differences of the hemispheres listed in Table 1 concern sequential (serial) processing of the left hemisphere and simultaneous (parallel) processing of the right hemisphere. This idea reflects the widespread – but not generally accepted – model, which says that the left hemisphere preferentially processes fast changes and analyses details and characteristics of stimuli, while the right hemisphere deals with the simultaneous and global characteristics of stimuli. The other hemispheric characteristics in Table 1 (analytical, rational vs. holistic, intuitive) are not very well supported by scientific evidence, and remain rather speculative. Starting from the difference between verbal and non-verbal, more and more abstract concepts and relations between mental functions and the hemispheres were developed. During this process, the ideas about the difference of the two hemispheres departed more and more from the basic scientific results. 

The two hemispheres and their ways of thinking

Some researchers interpreted the specialised functions of the two hemispheres as different thinking styles. Thus, the localisation of language and the proposed serial processing of stimuli in the left hemisphere were equated with a rational, analytical, logical thinking style, while the preponderance in the right hemisphere of non-verbal, visuo-spatial tasks, together with the proposed simultaneous processing, was equated with a holistic, intuitive, emotional way of thinking. In 1970, in his influential book “The Psychology of Consciousness“, the psychologist Robert Ornstein hypothesised that Western people only use half their brains and hence only half their mental capacity. He argued that people in Western cultures have a well trained left hemisphere, due to the focus on language and logical thinking. They do, however, neglect their right hemisphere and its intuitive, emotional way of thinking. In short, Ornstein equated the left hemisphere with an analytical, logic way of Western thinking, and the right hemisphere with an intuitive, emotional Eastern way of thinking. Thus the traditionally established dualism of intellect and intuition got a physiological foundation based on the differences of the two brain hemispheres. This view resulted in many misinterpretations and incorrect assertions, which were far from the scientific findings. Facts and conjecture became blurred and the two hemispheres of the brain were not only ascribed two different thinking styles, but also two different personality styles. The concept of right brain and left brain thinking, together with the idea of a dominant hemisphere, resulted in the notion that people rely predominantly on one or the other way of thinking, i.e. they rely on either the left or the right hemisphere. It has been supposed that this usage of one or the other half of the brain is reflected in the cognitive style of an individual: a person, who thinks rationally and analytically was said to be left hemispheric. In contrast, a person who processes information intuitively and emotionally was classified as right hemispheric. The hemispheric ways of thinking and of cognitive style became very popular and can nowadays be found in a variety of periodicals, workshops and self-help books. They even found their application in the field of education.

Hemispheric thinking and personality styles in learning and education

The concepts of right brain and left brain thinking and personality styles have raised many questions with regard to their application in education. Which learning and teaching styles consider the individual use of the hemispheres best? How should curricula be designed to guarantee whole-brained learning? Is our educational system too left-brained, with its focus on language and mathematics? How could right-brained skills be developed?

Joseph Bogen, one of the pioneers in split brain surgery, as well as the psychologist Robert Ornstein (see above), stated that our societies focus on a thinking style that uses statements (language) for information processing, i.e. the left hemispheric way of thinking. In contrast, they stated that our societies neglect right hemispheric thinking styles, such as creativity. The notion that our societies, including our education system, focus on only half of our mental capacities, i.e. the left hemispheric way of thinking, and neglects the other half, the right hemispheric way of thinking, became more and more widespread. Well-known educationalists, such as E.P. Torrance or Madeline Hunter, recommended that schools change the existing teaching methods and assessment procedures according to the concept of hemisphericity. Hunter stated that school curricula are predominantly aimed at left-brain learners. E.P. Torrance argued that schools favour left-brained activities, such as sitting erect or learning algebra, while right hemispheric functioning should include activities such as lying down or learning geometry. Others also supported the notion of a dominance of left brain functioning in education, arguing that the educational agenda of most schools revolves around left-brained subjects, such as language and mathematics. As a consequence, many whole-brained learning and teaching methods evolved. While these methods could be valuable in the educational setting, they are based on a shaky foundation. As we have seen, there is only some experimental support for the concept of hemisphericity. In addition, subsequent research has shown that things are neither quite as polarised as once thought, nor as simple. The application of this notion to educational practice seems, therefore, overly simplistic and even dubious.

Arguments against hemisphericity

Arguments against a left brain and right brain thinking style and its application to education

The notion of different hemispheric thinking styles is based on an erroneous premise: each brain hemisphere is specialised and therefore each must function independently with a different thinking style. This connection is a bridge too far: it uses scientific findings regarding functional asymmetries for the processing of stimuli to create conceptions about hemispheric differences on a different level, such as a cognitive thinking style. Furthermore, there is no direct scientific evidence supporting the idea that different thinking styles lie within each hemisphere. Indeed, deriving different hemispheric thinking styles from functional asymmetries is quite a bold venture, which oversimplifies and misinterprets scientific findings.

If one considers the right hemispheric creative and emotional thinking style, there is no scientific evidence that supports a correlation between creativity and the activity of the right hemisphere, let alone evidence for a correlation between the degree of creativity and the use of the right hemisphere. Similarly, a recent analysis of 65 neuroimaging studies on emotion found no scientific support for the hypothesis of an overall right hemispheric lateralisation of emotional function. There is no direct scientific evidence that supports an analytical, logical thinking style for the left hemisphere, which predetermines the left hemisphere for mathematical tasks, or reading and writing. In contrast, Stanislas Daheane found that both the right and left hemisphere are active in the identification of Arabic numerals (e.g. “1”,”2”). Similarly, other data showed that subsystems in both hemispheres are activated for parts of the reading process, e.g. decoding written words or recognising speech sounds. Based on these and many more scientific findings, scientists nowadays think that while there are some functional asymmetries, the two brain hemispheres do not work in isolation, but rather together in every cognitive task. In light of this notion, using the conception of hemisphericity to guide and direct educational practice is highly questionable.

References

Understanding the Brain: Towards a New Learning Science, OECD 2002, Chapter 4.6 pp.69-77.

Springer S.P. and Deutsch, G. (1998). Left brain, right brain. New York: W.H. Freeman.

Wagner T.D., Phan L.K., Liberzon, I., Taylor S.F. (2003) Valence, gender, and lateralization of functional brain anatomy in emotion: a meta-analysis of findings from neuroimaging. NeuroImage 19, 513-531

Zalewski L. J., Sink C. A., Yachimowicz D.J. (1992) Using Cerebral Dominance for Educational Programs. The Journal of General Psychology 119 (1), 45-57 

 

 

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