Why K Equals Blue and 5 Equals Green

Do you hear colours, taste shapes, or see sounds?

If so, don’t worry, you’re not crazy. Well you might be – but you may also have a condition known as synaesthesia. This is an unusual psychological phenomenon in which stimulation of one sense induces a response in multiple senses.

For instance, someone might perceive the letter K as blue, the number 5 as green, or taste as having a distinct colour.

One person with synaesthesia stated “To me, the taste of beef is dark blue. The smell of almonds is pale orange. And when tenor saxophones play, the music looks like a floating, suspended coiling snake-ball of lit-up purple neon tubes”.

Since synaesthesia rarely interferes with daily life, most synaesthetes assume that everyone is like them. As a result, the condition is underreported. The estimated prevalence of synaesthesia in Australian adults is 1 in 1150 females (0.087%) and 1 in 7150 males (0.014%).

Synaesthetic associations typically occurs during childhood and will generally remain consistent over time, sometimes even benefiting the individual in various ways. Psychological studies have shown that colour-grapheme synaesthesia, where someone involuntarily associates letters, numbers and words with particular colours, is quite useful in the detection of patterns.

One synaesthete was able to find 2 among 5’s consistently faster than other people. He later stated that he simply searched for a spot of orange! In contrast, he was slower at finding 8 among 6’s because to him both numbers appeared blue.

So what causes this peculiar neurological condition? There are numerous explanations. Synaesthesia commonly occurs within families, which suggests a genetic predisposition.

Others learn to associate letters to colours. Studies have found that those who experience colour-grapheme synaesthesia, often associate letters to the colours of the Fischer-Price refrigerator magnets they played with as kids. However this only partially explains the phenomenon, as synaesthetes can experience a multitude of different associations,

Another explanation is that axons from one sense invade brain areas responsible for another. Brain imaging research shows increased connections between brain areas that respond to colours, and areas that respond to letters and numbers in synaesthetic people.

While explaining the experience of synaesthesia remains a complex task, research is being conducted to discover methods which will provide the benefits of synaesthesia to people who have never experienced this truly bizarre phenomenon.