Seeing coloured numbers: not a mental illness

A vignette

Letters and Numbers as a synesthete sees

Ms. N. is thirteen now. She is sure that she is not mentally ill. But she is afraid that she will become a mental patient sooner or later if things are going on like this. She just started her plus one class after the 10^th standard in an English medium higher secondary school. She was just 11 when she came to know that she is different from other girls in her school. She wanted to know whether this difference is due to a kind of illness or madness. One day Ms. N. confided to her best friend Ms. S. that she was seeing coloured numbers on the black board when the teacher wrote them with white chalk, and as well as in the printed texts and written notes. Some lines are also seen coloured. After disclosing her odd experiences, Ms. N. asked her best friend: “S., my best friend, please tell me the truth; am I mad?” Ms. S. thought for a moment and replied: “No, my dear; you are not mad. But I think it is better to consult a doctor. Tell it to your father.”

Her father, an officer in the service of the state government, took her to a physician in the city. After detailed clinical examination the physician advised to do some investigations including laboratory examination of blood to find out whether there was any abnormalities in the blood contents such as electrolytes such as sodium, potassium, calcium etc., glucose, lipids and hormones. She was also advised to undergo a computed tomography (CT) scan of the brain. After perusing the results of all laboratory examinations and the report on the CT scan, the physician assured her that she was physically normal. To test for psychological abnormalities she was referred to me.

A case of synaesthesia

The mental status examination showed that Ms. N. was case of synaesthesia. A detailed mental status examination revealed no psychological abnormality except the anxiety caused by her odd experiences of seeing coloured numbers and letters in black and white texts. There is no cure for the condition called synaesthesia. To alleviate her anxiety I gave her psycho education on the subject of synaesthesia which was completed in three psychotherapeutic sessions.

Arises from cross wiring in the brain

Structure of a Neuron

Synaesthesia is a brain condition in which stimulation of one sensory modality or cognitive pathway leads to automatic experiences in a second sensory or cognitive pathway. The word synaesthesia was coined by conjoining two Greek words “syn” meaning togetherness and “aesthesis” meaning sensation. Synaesthesia means togetherness of different sensations which are normally perceived through distinct sensory modalities. In one common form of synesthesia, known as colour-graphemic synaesthesia, letters and numbers are perceived as coloured. People who have such experiences are known as synaesthetes. The cause of synaesthesia is cross wiring in the brain circuitry. Human brain is the most complexly organized structure in the universe. The central nervous system comprising of brain and spinal cord is composed of one trillion (10¹²) neurons. Every neurons is connected to other neurons through dendrites and axons which are the connecting organs extending from the cell body. The dendrites of a single neuron may receive as many as 10,000 connections from other neurons. The connection junctions are called synapses. Through synaptic connections the neurons in the brain form neural networks. A neural network is composed of a group or groups of functionally associated neurons. These complex formations of neural networks are called neural circuitry.  

Connections of Neurons

Different regions of the brain are specialized for given functions. Increased cross-connection between regions specialized for different functions may account for the many types of synesthesia. For example, the additive experience of seeing color when looking at numbers and words might be due to cross-activation of the word recognition area and the color area called V4 of the visual cortex of the brain. One line of thinking is that a failure to prune synapses that are normally formed in great excess during the first few years of life may cause such cross-activation.

“Visions of the sane persons”: First scientific article on synaesthesia

Francis Galton

Francis Galton was the first scientist to give a description of synaesthesia in his article titled “Visions of the Sane Persons”. The article was published in the FortnightlyReview  

 (29: 729–40) which was one of the most important and influential magazines in nineteenth-century England.

Not a disease

Although described as a neurological condition synaesthesia is not included in the disease classification manuals such as DSM  and ICD. 

How to identify synaesthesia?

American neurologist Richard Cytowic in his book The Man Who Tasted Shapes (2003) identified the following criteria of synesthesia to identify the real synaesthesia:

1. Synesthesia is involuntary and automatic.
2. Synesthetic percepts are consistent.
3. Synesthesia is highly memorable.
4. Synesthesia is laden with emotions.

Vilayanur S Ramachandran, Director of the Center for Brain and Cognition, “devised a simple computer display, a number of black 5s scattered on a white background. Embedded among those 5s there were a number of 2s forming a hidden shape. Since these are computer generated, 2s are just mirror images of the 5s.  Most people looking at this pattern see only a random jumble of numbers, but a synesthete sees the 5s as green and 2s as forming a red shape conspicuously visible against a forest of green.” (The Emerging Mind Page 21)

Experiences

Synesthetes often report that they were unaware their experiences were unusual until they realized other people did not have them, while others report feeling as if they had been keeping a secret their entire lives, as has been documented in interviews with synesthetes on how they discovered synesthesia in their childhood. The automatic and odd nature of a synesthetic experience means that the pairing may not seem out of the ordinary. This involuntary and consistent nature helps define synesthesia as a real experience. Most synesthetes report that their experiences are pleasant or neutral, although, in rare cases, synesthetes report that their experiences are embarrassing.

Different forms of synaesthesia

Synesthesia can occur by cross connection between any two sensory modalities. Researchers have adopted a convention of indicating the type of synesthesia by using the following notation x à y, where x is the "inducer" or trigger experience, and y is the "concurrent" or additional experience. For example, perceiving letters and numbers (collectively called graphemes) as colored would be indicated as grapheme à color synesthesia. Similarly, when synesthetes see colours or movement as a result of hearing musical tones, it would be indicated as tone à color or tone à movement synesthesia.

Grapheme à colour synaesthesia

This is the most common form of synesthesia. Here individual letters of the alphabet and numbers are "shaded" or "tinged" with a colour. While different individuals usually do not report the same colours for all letters and numbers, studies with large numbers of synesthetes find some commonalities across letters (e.g., A is likely to be red).

Patricia Lynne Duffy, author of the book Blue Cats and Chartreuse Kittens: How Synesthetes Color their Worlds is a synesthete. As a child, Pat Duffy told her father, "I realized that to make an R all I had to do was first write a P and draw a line down from its loop. And I was so surprised that I could turn a yellow letter into an orange letter just by adding a line."   

Sound à colour synesthesia

According to Richard Cytowic, sound à color synesthesia is "something like fireworks": voice, music, and assorted environmental sounds such as clattering dishes or dog barks trigger color and firework shapes that arise, move around, and then fade when the sound ends.  For some, the stimulus type is limited (e.g., music only, or even just a specific musical key); for others, a wide variety of sounds triggers synesthesia.

Number form synesthesia

A number form is a mental map of numbers, which automatically and involuntarily appears whenever someone who experiences number-forms thinks of numbers. Number forms were first documented and named by Francis Galton in "The Visions of Sane Persons."  It has been suggested that number-forms are a result of "cross-activation" between regions of the parietal lobe of brain that are involved in numerical cognition and spatial cognition.

Ordinal-linguistic personification 

In linguistics, ordinal numbers are the words representing the rank of a number with respect to some order, in particular order or position (i.e. first, second, third, etc.). Its use may refer to size, importance, chronology, etc. They are different from the cardinal numbers (one, two, three, etc.) referring to the quantity. Ordinal-linguistic personification (OLP, or personification for short) is a form of synesthesia in which ordered sequences, such as ordinal numbers, days, months and letters are associated with personalities.  For example, one synesthete says, "T’s are generally crabbed, ungenerous creatures. U is a soulless sort of thing. 4 is honest, but… 3 I cannot trust… 9 is dark, a gentleman, tall and graceful, but politic under his suavity." (Calkins MW (1893). "A Statistical Study of Pseudo-Chromesthesia and of Mental-Forms". The American Journal of Psychology  (University of Illinois Press) 5 (4): 439–64.)

Lexical à gustatory synaesthesia

In the rare lexical à gustatory synesthesia, individual words and the phonemes of spoken language evoke taste sensations in the mouth. James Wannerton, president of the UK Synaesthesia Association says: "Whenever I hear, read, or articulate (inner speech) words or word sounds, I experience an immediate and involuntary taste sensation on my tongue. These very specific taste associations never change and have remained the same for as long as I can remember." Wannerton laments: “Synaesthesia can be difficult to live with. I can't really read books, as each word sets off a new taste; and I have to really concentrate when I'm driving, as road signs do the same.”