Left and Right Side of the Human Brain: Functions and Specific Roles
The human brain has two cerebral hemispheres. Each has areas of specialisation, but they communicate constantly and work together — which is why the popular idea of "left-brained" and "right-brained" people doesn't hold up.
Introduction
The human brain is one of the most complex organs in the body. It controls movement, senses, language, memory, thinking, emotions and many other activities.
The cerebrum, which makes up most of the brain, is divided into two major parts called the left hemisphere and the right hemisphere. These two sides are connected by a large bundle of nerve fibres called the corpus callosum, which allows information to move between them so they can work together.
Quick overview: The two sides of the brain have some different areas of specialisation, but normal thinking and behaviour usually involve both sides working together.
What are the left and right hemispheres?
The brain is divided into two cerebral hemispheres by a deep groove. The left hemisphere sits on the left side of the brain, the right hemisphere on the right.
The two are not separate organs. The corpus callosum acts as a communication bridge between them, transferring sensory, motor and higher-level information.
Some functions show stronger activity or specialisation on one side than the other. However, it is not correct to think that one side works alone for any particular activity. Most everyday tasks require cooperation between both hemispheres.
Functions of the left side of the brain
In most people, the left hemisphere has an important role in language. It also contributes to several analytical and sequential tasks.
1. Language and speech
For most people, important language functions such as producing and understanding spoken and written language are more strongly represented in the left hemisphere.
2. Reading and writing
The left hemisphere contributes strongly to processing language during reading and writing. It helps us recognise words, understand meaning and organise written communication.
3. Analytical thinking
The left hemisphere is often more involved in analysing information in a detailed and structured way. This supports activities that require rules, sequences and logical relationships.
4. Mathematical processing
Some aspects of numerical and mathematical processing are more strongly associated with the left hemisphere, although mathematics involves several brain regions across both sides.
5. Control of the right side of the body
The left hemisphere generally controls voluntary movement and receives much of the sensory information from the right side of the body, through pathways that cross between the two sides of the nervous system.
Functions of the right side of the brain
The right hemisphere is particularly important for several visual, spatial and non-verbal abilities. It also contributes to recognising patterns and faces.
1. Visual and spatial processing
The right hemisphere has an important role in understanding spatial relationships, visual patterns and where objects are located in relation to one another.
2. Face recognition
The right hemisphere contributes strongly to recognising faces and processing complex visual information.
3. Understanding patterns
The right side helps with recognising patterns, shapes and relationships in visual information — useful when interpreting a scene or understanding the overall arrangement of what you're looking at.
4. Non-verbal information
The right hemisphere contributes to processing non-verbal information, including aspects of tone of voice, visual cues and emotional signals.
5. Control of the left side of the body
The right hemisphere generally controls voluntary movement and receives much of the sensory information from the left side of the body.
Left and right: simple comparison
| Left hemisphere | Right hemisphere |
|---|---|
| Strongly involved in language in most people | Important for visual and spatial processing |
| Supports reading and writing | Contributes to face recognition |
| Supports detailed and sequential processing | Supports pattern and overall visual processing |
| Contributes to mathematical and analytical processing | Contributes to non-verbal and emotional information |
| Generally controls the right side of the body | Generally controls the left side of the body |
How both sides work together
Although the hemispheres have areas of specialisation, they do not work as two independent brains. The corpus callosum lets them exchange information and coordinate their activity.
Reading a story, for example, involves language processing alongside visual processing. Following a conversation involves words, tone of voice, memory, attention and emotional information at once. These abilities draw on networks across both sides.
This cooperation matters because the brain has to combine different types of information to carry out even ordinary daily activities.
Are people completely left-brained or right-brained?
A common idea is that some people are entirely "left-brained" and logical while others are entirely "right-brained" and creative. This is an oversimplification.
Research shows the hemispheres do have specialised functions, but human behaviour is far more complex than two personality types. Different tasks recruit networks of brain regions, and the hemispheres are in constant communication.
Being good at mathematics does not mean a person only uses the left side of their brain, and being creative does not mean they only use the right.
Where the myth came from: it grew out of genuine research in the 1960s on patients whose corpus callosum had been surgically divided to treat severe epilepsy. Those findings were real — but they described a rare surgical condition, not how personality works in an intact brain.
Conclusion
The two hemispheres of the human brain have some different areas of specialisation. The left is especially important for language in most people, while the right contributes strongly to visual, spatial and non-verbal processing.
The most important point, though, is that both sides work together. The corpus callosum allows them to communicate, letting the brain combine language, movement, vision, memory and attention into a single coherent experience.
Key takeaways
- The brain has two main cerebral hemispheres.
- The left hemisphere has an important role in language for most people.
- The right hemisphere is strongly involved in visual and spatial processing.
- Each hemisphere generally controls the opposite side of the body.
- The corpus callosum allows the two sides to communicate.
- Most complex activities involve cooperation between both sides.
Note: This article is general information about how the brain is organised, not medical advice. Any concerns about brain function, memory or speech should be discussed with a doctor.
About the writer
Thank you for reading this guide to the two sides of the human brain. I publish well-researched articles covering health, nutrition, biotechnology, Artificial Intelligence, emerging technologies and digital productivity.