A person hears a piece of music and, at the same time, sees a deep blue colour. Another reads a word and senses a light taste, as if flavour has entered the sentence. Someone else looks at a number and feels that it has weight, shape, or feeling. For these people, such experiences are not imagination or figures of speech. They are steady parts of how they sense the world.
This experience is called synesthesia. It is a neurological condition where one sense triggers another automatically. A sound may bring colour. A written word may bring taste. A number may bring feeling or space. These experiences are real perceptions, not symbols or ideas. They happen without effort and stay the same over time.
What sets synesthesia apart from imagination is consistency. The same thing causes the same response repeatedly, often throughout life. A letter that looks blue does not slowly change colour. A musical note that feels bright or heavy keeps that quality. This steadiness has helped researchers study synesthesia as a natural difference in perception, not a passing thought.
Synesthesia is not an illness. It does not reduce intelligence, judgement, or daily ability. Large studies in education, health and psychology show that people with synesthesia function like everyone else in most areas. In some areas, especially memory and recognising patterns, they often perform slightly better. These benefits do not appear in everyone, but they appear often enough to matter.
Brain research helps explain this. In most people, the senses become more separate as the brain develops. Each sense works on its own. In people with synesthesia, some of these links stay more open. Brain scans and body measures suggest that synesthetic experiences use real sensory systems, not effortful imagination. Even small body reactions, such as changes in pupil size, match the colours people report seeing.
Synesthesia exists in many forms. One common type links letters and numbers with colour. Another links sound with colour, including pitch, tone, or voice. Other types involve taste, touch, the way time feels in space, or emotional responses to ideas. Some forms connect senses with meaning rather than with another sense, showing that synesthesia goes beyond the usual five senses.
Studies of development suggest that synesthesia often starts in early childhood. Many people only realise later that their experiences are different. This often happens when they learn that others do not sense things the same way. Research also shows that synesthesia can run in families, although family members may experience it in different forms. This suggests a shared tendency to connect senses, not fixed pairings.
Synesthesia appears often among musicians, artists, writers and designers. Musicians, in particular, show higher rates than the general public. This does not mean synesthesia causes creativity. It does suggest that extra sensory links can enrich thinking. When sound carries colour or language brings feeling, creative work can draw on more internal detail. For some people, this supports structure, memory and expression.
Synesthesia has also been studied in medical and brain related settings. Research that looks at its presence alongside epilepsy or other conditions stresses the need for care. Links exist, but they do not mean illness. Instead, they show that synesthesia can exist alongside many different life and thinking patterns. Clear language helps avoid confusion between difference and disorder.
Recent studies have moved beyond simple lab tests. Researchers now use dream reports, immersive environments and computer models to study synesthesia in more natural settings. These methods suggest that synesthesia affects both what people sense and how they organise, remember and describe experience. It shapes how information feels, not only how it is handled.
More broadly, synesthesia questions the idea that everyone senses the world in the same way. It reminds us that the brain shapes experience. What people call reality passes through neural systems that differ from person to person. Some minds keep information separate. Others blend it more freely. Neither way is wrong. Both reflect the range of human thinking.
Dr Khalfan bin Hamed al Harrasi
The author is an academic and researcher
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