Do you smell colours? Or taste numbers? You might have synesthesia.
Synesthesia is a condition of ‘joined perception’, where people affected perceive one sense with another. The five senses that humans experience are touch, smell, sight, noise and hearing. People that experience synesthesia, known as synesthetes, can perceive one or more senses simultaneously.
Some examples are:
- Tasting coffee when you see a specific telephone
- Feeling an itch every time you hear a car horn
- Seeing the number 5 as blue
- Having a different personality on certain days of the week (okay this one does sound normal)
Synesthesia is thought to affect about 1 in 20 people, and all synesthetes experience different associations. These associations generally develop in childhood, as a specific stimulus (such as seeing a Nokia 3310) will trigger a highly specific sense (tasting coffee).
Most commonly, synesthetes associate numbers and words with colours – called grapheme-colour synesthesia. One published account of synesthesia described a young girl associating a colour with a particular word. She described how she could always tell when the word was misspelled, as letters with different colours were added to the word – making it look strange! For example, she would see definitely in red, but if it was misspelled as definately, she could notice that the spelling was wrong due to the coloured letter a out of place.
So why do these people experience these overlapping senses? Well it comes down to the nervous system, more specifically the wiring of the brain. Usually when we experience a sense, for example taste, the food will chemically react with your taste buds and send a message to your brain that recognizes this taste. It is thought that in synesthesia, neurons (brain connections) overlap and can trigger other senses to be activated (see image).
A study published in Nature Neuroscience (Rouw, R., 2007) found that synesthetes had greater regions of connectivity in the brain, than non-synesthetes. This was found by analyzing MRI scans of synesthetes, at points where they were exposed to coloured numbers and coloured words. This suggests that these extra connections between the sensory pathways in the brain can trigger each other, leading synesthetes to experience one or more senses for a single stimuli.
From what I gather, synesthesia is a neurological experience – not necessarily a neurological condition. Most synesthetes report that they experience pleasure with their sensory overlaps. I must admit I do associate colours with words sometimes… or maybe I am just trying to find an excuse to have some extra cool pathways in my brain.