“People are either left-brained or right-brained.”

• Hemispheric specialization is genuinely real: language production is left-lateralized in roughly 95% of right-handers, while some visuospatial and face-processing functions show right-hemisphere bias — so the underlying idea of 'sided' brain functions has a factual kernel (Corballis, PLoS Biology 2014).
• Roger Sperry's Nobel-recognized split-brain research showed that when the corpus callosum is severed, the two hemispheres can process information independently and display different competencies, which is the historical origin of the popular claim.
• There is real inter-individual variation in the direction of lateralization — a minority of people (notably some left-handers) have right-hemisphere or bilateral language dominance — so 'which side is dominant' is not identical in everyone for a given function.
• The belief is extremely widespread among educators and the public, which is sometimes cited as informal support; surveys of teachers find majority endorsement of left/right-brain learner typologies (Dekker et al., Frontiers in Psychology 2012).

• A University of Utah fMRI study of resting-state functional connectivity in 1,011 people aged 7–29 found no evidence that individuals preferentially use a left-brain or right-brain network; lateralization patterns were consistent across people rather than sorting them into two types (Nielsen et al., PLoS ONE 2013).
• Lateralization is function-specific, not person-wide: an individual can be strongly left-lateralized for speech and right-lateralized for some spatial or prosodic tasks at the same time, so there is no coherent 'dominant hemisphere' for a whole person (Corballis, PLoS Biology 2014).
• Virtually all complex behavior — language, math, creativity, logic — recruits distributed networks in both hemispheres linked by the corpus callosum; 'creativity' and 'logic' have never been localized to one hemisphere.
• There is no evidence linking hemispheric asymmetry to personality traits, learning style, or aptitude; 'left-brained/right-brained' learning-style instruction is classified as a neuromyth by education-neuroscience researchers (Dekker et al. 2012).
• The claim's dichotomous framing ('either...or') is falsified by the data even where lateralization exists: asymmetry is a continuous, graded measure, not a binary category.
• Split-brain findings apply to patients with a surgically severed corpus callosum and do not generalize to intact brains, where the hemispheres exchange information continuously (Corballis 2014; Sperry's own work concerned commissurotomy patients).

96/100 — the lab’s own confidence in the score above, not a second reading of the claim.

PLOS ONE (Nielsen, Zielinski, Ferguson, Lainhart & Anderson, 2013)journal · 92 · PLOS Biology (Corballis, 'Left Brain, Right Brain: Facts and Fantasies')journal · 93 · Frontiers in Psychology (Dekker et al., 'Neuromyths in Education')journal · 85 · The Nobel Prize (Roger Sperry Nobel Lecture, 1981)other · 88 · Live Sciencenews · 70 · Psychology Today (Christian Jarrett, 'Brain Myths')news · 65

• There is a real kernel of truth: human brains show hemispheric specialization. For example, language is usually more left-lateralized, while some visuospatial and attentional functions are often more right-lateralized; split-brain research also shows that the two hemispheres can process information differently.
• Brain lateralization can vary across individuals and tasks, so casual observations that someone has relatively stronger verbal, spatial, analytical, or creative skills may appear to align with the popular left/right-brain story.

• The claim as written says people are either one type or the other. A large resting-state fMRI study of 1,011 people found no evidence that individuals generally have stronger left-hemisphere or right-hemisphere brain networks; localized lateralization exists, but people do not sort into globally 'left-brained' or 'right-brained' categories.
• Peer-reviewed reviews describe the popular personality dichotomy—left brain as logical/analytical and right brain as creative/intuitive—as a myth or 'fantasy' built from real but limited hemispheric specialization.
• Normal cognition relies on distributed, interacting networks across both hemispheres. A person may show left-lateralization for one function and right-lateralization for another, which contradicts a simple either/or classification.
• Education research identifies 'left-brained/right-brained learners' as a common neuromyth, warning that using it to classify people or tailor instruction is unsupported.

96/100 — the lab’s own confidence in the score above, not a second reading of the claim.

PLOS ONEjournal · 95 · PLOS Biologyjournal · 95 · Frontiers in Psychologyjournal · 88 · National Institute of Neurological Disorders and Strokegov · 92

• The claim stems from a genuine neuroscientific concept known as 'brain lateralization,' which notes that certain cognitive processes are more localized to one side of the brain than the other.
• Nobel laureate Roger Sperry's famous 'split-brain' experiments in the 1960s demonstrated that the left hemisphere is typically more specialized for language and speech, while the right hemisphere is more involved in spatial processing and facial recognition.
• Popular psychology and self-help industries took these specific findings of localized function and exaggerated them to formulate the appealing, though unscientific, narrative of left- or right-brain 'dominance' dictating a person's entire personality.

• A comprehensive 2013 neuroimaging study by researchers at the University of Utah analyzed the resting brain scans of over 1,000 individuals and found no evidence of whole-brain hemispheric dominance (i.e., individuals did not have stronger left-sided or right-sided brain networks).
• Modern neuroscience shows that the brain functions as a highly interconnected network. Complex tasks—whether they are logical, mathematical, artistic, or creative—require continuous communication between both hemispheres across the corpus callosum.
• There is no empirical evidence to support the idea that logical, analytical people are 'left-brained' or that creative, artistic people are 'right-brained.' It is widely classified by neuroscientists as a 'neuromyth.'

99/100 — the lab’s own confidence in the score above, not a second reading of the claim.

PubMed Central / PLOS ONEjournal · 95 · Healthlineother · 80

• The claim has a limited basis in the scientifically established fact that the two cerebral hemispheres show functional specialization: language is often more left-lateralized, while some spatial and attentional functions are more right-lateralized.[2][6]
• Split-brain and other lateralization research supports the conclusion that the hemispheres do not have identical functions, so “left-brained” and “right-brained” can loosely describe some task-specific specialization.[2][6]

• The claim says people are either left-brained or right-brained, implying a person-level, overall dominance. A 2013 brain-imaging study of 1,011 people found no evidence that individuals preferentially use a globally stronger left- or right-hemisphere network.[3][6]
• The same research found that left- and right-lateralized connections were local properties of brain networks, not a whole-brain trait distinguishing people as left-brained or right-brained.[3]
• Research and expert reviews find little or no evidence that personality traits such as creativity, rationality, or intuition reside in one hemisphere or determine whether someone is left- or right-brained.[1][4]
• The brain normally operates through cooperation between both hemispheres; task-specific lateralization does not establish that a person uses one side overall.[1][10]
• The idea that scientific or logical people are left-brained and creative or intuitive people are right-brained is described as a myth or oversimplification rather than an anatomically accurate classification.[1][4][15]

98/100 — the lab’s own confidence in the score above, not a second reading of the claim.

Harvard Health Publishingedu · 95 · PLOS Biology via PubMed Central and NIHjournal · 97 · PLOS ONE via PubMed Central and NIHjournal · 98 · University of Utah Healthedu · 94 · McGill University Office for Science and Societyedu · 93 · Frontiers in Psychology via PubMed Central and NIHjournal · 96 · Medical News Todaynews · 82

• The two cerebral hemispheres are functionally specialized in most people (e.g., language production and some sequential/analytical processing more often left-lateralized; some visuospatial, attentional, and face-processing functions more often right-lateralized), established by lesion studies, Wada testing, and neuroimaging.
• Split-brain research (Sperry, Gazzaniga and others) showed that disconnected hemispheres can process information somewhat independently, which historically inspired the popular left/right-person typology.
• Individuals differ in degree of lateralization, and handedness is modestly related to language lateralization, so a weak individual-difference story exists even if it does not support two personality types.

• The claim as written is the popular typology that people are one type or the other (logical/analytical vs creative/intuitive) because one hemisphere dominates. Large-scale resting-state fMRI of more than 1,000 people found no evidence of a left- or right-dominant brain-wide connectivity pattern that would make someone 'left-brained' or 'right-brained'.
• In an intact brain the hemispheres work together; most complex functions including language, reasoning, and creativity recruit distributed bilateral networks, not a single dominant hemisphere.
• The mapping of personality and cognitive style onto left vs right hemispheres is not supported by neuroscience and is repeatedly classified as a neuromyth in education and cognitive neuroscience reviews.
• People therefore are not classifiable as either left-brained or right-brained; the binary is false even though some hemispheric specialization is real.

90/100 — the lab’s own confidence in the score above, not a second reading of the claim.

PLOS ONEjournal · 88 · PLOS Biologyjournal · 93 · Nature Reviews Neurosciencejournal · 97