Left vs Right Hemisphere: What Each Side Really Does
Are people left-brained or right-brained?
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Midline view
The Short Answer
No. Each hemisphere does lean toward certain jobs - in most people, the left handles most of language and the right leads on spatial attention and recognising faces - but both sides work together on almost everything, linked by the corpus callosum. A study of over 1,000 brain scans found no evidence that individuals are dominated by one whole side.
At a Glance
| Aspect | Left hemisphere | Right hemisphere |
|---|---|---|
| Body control | Movement and touch on the right side of the body | Movement and touch on the left side of the body |
| Language | Dominant in most people: grammar, vocabulary, and producing speech | Tone of voice, emotional emphasis, humour, and reading between the lines |
| Attention to space | Attends mainly to the right side of space | Attends to both sides, which is why neglect of one side is more common after right-hemisphere damage |
| Faces | Contributes, especially to identifying features and names | Often stronger responses to faces in its fusiform face area |
| Vision | Sees the right half of the visual field | Sees the left half of the visual field |
| "Logical" vs "creative" | Not supported: logic and creativity both use networks on both sides | Not supported: creativity draws on both hemispheres |
Where the Idea Came From
The "left brain, right brain" idea grew out of real science. In the 1960s, Roger Sperry and Michael Gazzaniga studied patients whose corpus callosum had been cut to treat epilepsy. By showing information to one hemisphere at a time, they found that the left hemisphere could usually describe what it saw in words, while the right often couldn't - though it could recognise objects, match pictures, and guide the left hand. Sperry shared the 1981 Nobel Prize for this work.
Popular books in the following decades stretched these findings far beyond the evidence, describing the left hemisphere as logical and analytical and the right as creative and intuitive - and then claiming that individual people are dominated by one side. The research never showed that.
What Really Differs
Body control is crossed. Each hemisphere controls movement and receives touch from the opposite side of the body, and sees the opposite half of the visual field. This is why a stroke in the left hemisphere usually affects the right side of the body.
Language leans left. In a 2000 study of 326 healthy people, Stefan Knecht and colleagues found language was dominant on the right in just 4% of strong right-handers and 27% of strong left-handers - so even most left-handers use the left hemisphere for language. The right hemisphere still contributes melody, emotional tone, and context.
Spatial attention leans right. The left hemisphere attends mainly to the right side of space, while the right hemisphere attends to both sides. As a result, damage to the right parietal lobe can cause "neglect", where a person ignores the left side of their world, while the equivalent left-sided damage rarely causes such severe neglect.
Faces lean right. When Nancy Kanwisher identified the brain's face-selective area in 1997, it was found in the right hemisphere more consistently than the left.
Why Nobody Is "Left-Brained"
In 2013, Jared Nielsen and colleagues analysed resting brain scans from over 1,000 people, looking for individuals whose left- or right-hemisphere networks were stronger overall. They found that specific networks were lateralised, but that people didn't differ in having a "more left" or "more right" brain as a whole. Personality traits like being analytical or artistic aren't explained by one hemisphere winning out.
The two hemispheres are also in constant conversation. Around 200 million nerve fibres in the corpus callosum let each side share what it's doing many times a second, so almost every real-world task - reading a story, solving a puzzle, painting - draws on both.
Common Myths
"Creative people use their right brain."
Creative thinking involves widespread networks in both hemispheres, especially those linking the frontal lobes with areas involved in memory and imagination.
"You can train yourself to use your 'weaker' side."
Products promising to "balance" or "activate" one hemisphere aren't supported by evidence. Practising a skill improves the networks that skill uses, wherever they are.
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Key Terms
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Sources & Further Reading
- Forty-five years of split-brain research and still going strong - Gazzaniga (2005), Nature Reviews Neuroscience
- Handedness and hemispheric language dominance in healthy humans - Knecht et al. (2000), Brain
- Spatial neglect and attention networks - Corbetta & Shulman (2011), Annual Review of Neuroscience
- The fusiform face area: a module in human extrastriate cortex specialized for face perception - Kanwisher et al. (1997), The Journal of Neuroscience
- An evaluation of the left-brain vs. right-brain hypothesis with resting state functional connectivity MRI - Nielsen et al. (2013), PLOS ONE