Synaesthesia : When the senses get mixed up !

We have learnt about five different senses of our body during our primary education. But have we ever thought what would happen if our senses mix up? Or if people could smell sound, taste words and see numbers as colours? It is even impossible to think of such a condition but it actually exists and such a condition is termed as synaesthesia.


Synaesthesia is a curious condition where there is the fusing of the senses due to cross-wiring in the brain. It is a rare condition but broad neurological phenomenon, where stimulation of one sensory automatically stimulates a second sensory pathway. People who report a lifelong history of such experiences are known as synesthetes. During this condition combination of almost any two senses of the five senses is possible. So here one synesthete will taste beef whenever they see the word window and another will visualise colour blue when they hear a musical cue. Usually our brain would interpret the signals from ears as sound but in this case people experience sounds as colours or smells as colours. Researchers have found that 1 in 2000 people have synaesthesia and is generally passed from parent to child and is more common among females. Synaesthesia is not considered a disease and those affected usually have higher level of intelligence.

What causes synaesthesia?

Scientists do not have clear explanations for this. They are not sure of what is occurring within the brain of a synesthete. But recent studies explain that it is because of the additional connections within the brain. Normally when individuals process colour(sight) the reflected light from the object hits the colour receptors in the eye. The image is processed for details. Information on colour is sent to fusiform gyrus of the temporal lobe, where it is then sent further along in the brain for even more detailed processing. Information on numbers is also processed in the same manner. The problem arises here. Due to close proximity at which both the numbers and colours are processed, it has been suspected that the cross wiring occur within these closely related areas. Similarly the auditory processing centre in the brain is close to the area of the brain that receives the colour. This explains for the sound-colour synaesthesia. The fascinating hypothesis states that all babies, until an age of around four months old are unable to differentiate between senses. This explains that we all are synesthete when born. But this hypothesis does raise a very important question: if we are all born synesthetes, what must occur within the brain to allow one individual to experience synaesthesia into adulthood and another to lose the ability?

Common traits of synaesthesia

  • Preference for order, symmetry, neatness and balance
  • Prone to déjà vu, clairvoyance, precognitive dreams and feeling the presence of others
  • Right-left hand confusion (or allochiria)
  • Mathematical abilities and spatial navigation are below average
  • Being left-handed & above-average intelligence level
  • Going into a career field where creativity is demanded (arts, music, etc.)

The different types of synaesthesia are:

Grapheme is the colour synaesthesia. A person with this type of synaesthesia will associate different colours with different letters or numbers.



Sound to colour synaesthesia where a person would see geometric shapes or colours while listening to sound



In number form synaesthesia any time the person thinks of a number he/she makes a number map in their mind



Personification is a form in which the person will associate different letters or numbers with different personalities. They may also give objects the personality traits such as anger for letter ‘A’.



Let’s take a synaesthesia test.

Take a look at this image. Most of the people would answer that they see lots of 5’s in this image. But if we look into the image for some more time we can see that some of the 5’s are reversed into 2’s or there are few 2’s among those 5’s. This condition is taken for the normal people. In case if the person has number-colour synaesthesia then he would immediately identify a triangle of 2’s. This is because they would see two different colours for those two different numbers.


Is there any treatment for synaesthesia?

Synaesthesia is considered to be an ability more than a disability. Hence most of the people do not go in for any treatments. Moreover we cannot prevent this because it is due to a genetic difference. There is only one treatment for this and that is hypnosis. This is an effective treatment for synaesthesia. The same hypnotic treatment used for severe phobias is used for this.

Everyday we can see the advancements in science and technology. But there are no proper equipments to treat such disabilities and cure them thoroughly. Biomedical sciences are entering into their phase of development, but paradoxically many people are still living with dysfunctional health care system. Should we blame evolution for some of the most pressing health problems that we face today? Some day we would be worried about the consequences of our increasing knowledge.




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