The Myth of the Left Right Brain Myth

Over the last few years I have been told many times that Left/Right brain theory has been debunked and is no longer relevent to any discussion of human perception or behaviour. When I ask about the evidence for such a claim very few people can offer an explanation other than they heard about it somewhere, so I thought it would be interesting to put together a page with relevant data, and you can make up your own mind.

This seems to be the kind of quote that has become the staple of anyone wishing to dismiss the idea that there is a significant functional or perceptual difference between our cerebral hemispheres. It appears to rule out the idea that both our cerebral hemispheres have been structurally, functionally and perceptually failing for a long time and that our left hemisphere is much more seriously affected than our right hemisphere.  

'One of the most ridiculous ideas out there about the brain’s role in creativity is that some people are logical and analytical by nature while others are creative.' Dr Rahul Jandial For The Daily Mail 16/06/2019

So to begin, this is the study being referred to by Dr Jandial and by proxy pretty much everyone else who confidently allude to new research  stating the hemispheres work together and even that it debunks any significant differences between the left and right hemisphere .

An Evaluation of the Left-Brain vs. Right-Brain Hypothesis with Resting State Functional Connectivity Magnetic Resonance Imaging

It seems to be the study that replaced the undoubtedly overly simplistic interpretations of decades of left/right brain research that had become urban myths with completely unsubstantiated new myth that is used to dismiss anything to do with left/right brain research.

(January 2020) I have not had time to put a summary together, will do soon.  In the meantime it is not difficult to look at the data rather than buy into the overly simplistic interpretations of the study above.

Cerebral asymmetry

The hemispheres are not equal: How the brain is not symmetrical

Divided brains: The biology and behaviour of brain asymmetries.

The Divided Brain: Iain McGilchrist explains ‘why we are so unhappy’ (links to additional material)



Selective atrophy of left hemisphere and frontal lobe of the brain in old men.

The Evolutionary Biology of Self-Deception, Laughter, Dreaming and Depression: Some Clues from Anosognosia

Left–right asymmetries of behaviour and nervous system in invertebrates


The significance of the temporal lobes and of hemispheric dominance in the production of the LSD-25 symptomatology in man:

Split brain behavioural experiments
Severed Corpus Callosum pt_1
Severed Corpus Callosum pt_2

Cerebral LateralizationBiological Mechanisms, Associations, and Pathology: I. A Hypothesis and a Program for Research
Foetal oestrogens and autism
Fetal Testosterone Influences Sexually Dimorphic Gray Matter in the Human Brain
Fetal testosterone and autistic traits.
Testosterone-Related Cortical Maturation Across Childhood and Adolescence
Developmental effects of androgens in the human brain.
Testing the Empathizing–Systemizing theory of sex differences and the Extreme Male Brain theory of autism in half a million people
Brain's synaptic pruning continues into your 20s
Extraordinary neoteny of synaptic spines in the human prefrontal cortex
When does age-related cognitive decline begin?
Development and Aging of the Cerebrum: Assessment with Proton MR Spectroscopy
Smaller left hemisphere planum temporale in adults with autistic disorder.
Abnormal Brain Lateralization in High-Functioning Autism
Dissociation of anosognosia for hemiplegia and aphasia during left-hemisphere anesthesia.

Christie et al. Global versus local processing: seeing the left side of the forest and the right side of the trees Front Hum Neurosci. 2012; 6: 28.
Neurophilosophy. The delusional brain, January 20, 2009.
New York University School of Medicine. Delusions Associated With Consistent Pattern Of Brain Injury ScienceDaily, 13 January 2009.

Treffert D.  The savant syndrome: an extraordinary condition. A synopsis: past, present, future
Philos Trans R Soc Lond B Biol Sci. 364(1522): 1351–1357, 2009 May 27.
Treffert D.The “Acquired” Savant Could such dormant potential exist within us all? Wisconsin Medical Society (2010)
Snyder  A. Explaining and inducing savant skills: privileged access to lower level, less-processed information Philos Trans R Soc Lond B Biol Sci. 364(1522): 1399–1405. 2009 May 27.
Laino  C. As Dementia Sets In, Artistic Genius Emerges  Neurology Today: Volume 3, p 14–15. June 2003.
Zukowski M. Math genius, savant Jason Padgett visits Fond du Lac USA Today. Oct 4, 2016.

Kolb B. et al. Brain Plasticity and Behaviour in the Developing Brain J Can Acad Child Adolesc Psychiatry, 20:4, November 2011
Adhya D. et al. Understanding the role of steroids in typical and atypical brain development: Advantages of using a “brain in a dish” approach J Neuroendocrinol. 2018 Feb; 30.
Small T. et al. Testosterone Mediates Seasonal Growth of the Song Control Nuclei in a Tropical Bird Brain Behav Evol; 86:110-121,2015.
Hodgetts S. The neuromodulatory properties of gonadal steroid hormones with regard to individual differences in cognition and brain organisation. Faculty of Science > Psychology, Department of  24 Nov 2016.
Greenberg, D. et al. Testing the Empathizing–Systemizing theory of sex differences and the Extreme Male Brain theory of autism in half a million people PNAS 115 (48) 12152-12157, November 27, 2018.
Rathee P. et al. Mechanism of Action of Flavonoids as Anti-inflammatory Agents: A Review Inflammation & Allergy - Drug Targets, 229-235, August 2009.
Savitz J. et al. Dissociative Identity Disorder Associated with Mania and Change in Handedness Cog Behav Neurol, Volume 17, Number 4, December 2004
Brainwaves suppress obvious ideas to help us think more creatively Queen Mary, University of London December 10, 2018
 Keenan J. et al. The Causal Role of the Right Hemisphere in Self-Awareness: It is the Brain that is Selective Published in Cortex, volume 43, pages 1074-1082, 2007.
Ramachandran V.S. Anosognosia in Parietal Lobe Syndrome Consciousness and Cognition Volume 4, Issue 1, Pages 22-51, March 1995.
Kovalev VA. et al. Gender and age effects in structural brain asymmetry as measured by MRI texture analysis.  Neuroimage. 2003 Jul;19(3):895-905.
Santarnecchi E. et al. Gamma tACS over the temporal lobe increases the occurrence of Eureka! moments  Scientific Reports volume 9, Article number: 5778, 2019.


On creativity (part II)


How to Escape the Confines of Time and Space According to the CIA