The Magic of Hearing Colors
Synesthesia, a rare neurological condition, describes an involuntary, automatic union of the senses or secondary experience caused by an external stimulus. The word “synesthesia” comes from the Greek meaning “to perceive together.” These secondary experiences often occur through separate modes such as an internal auditory association with a visual stimulus. Whether the original information is tangible, audible, or visual, the key identifier of synesthesia is simultaneous, intermixed sensory experiences. (E. Dalton, 2013)
Synesthesia tends to be more common in women, and more common in children. 72% of self-reported synesthetes are female, says The Synesthesia List website. Most synesthetes report having had synesthetic perception since childhood, although synesthesia can also be caused by brain damage or by psychoactive drugs such as LSD. In some cases, synesthesia disappears later in life, usually after puberty, it also tends to run in families. It is estimated that 1/23 people have some type of synesthesia (Simner, et. al. 2005), and the first known reports of synesthesia come as early as 1880, from Francis Galton.
The kinds of Synesthesia are Idiopathic Synesthesia, which is not a disorder per se, but a perceptual curiosity occurring in roughly 1 in 25,000 individuals. Although the five senses yield 20 possible pair-wise combinations, some synesthetic combinations are much more common than others. Yoking of sight with sound is by far most frequent, touch and taste less so, and smell is least often involved. Color, movement, and geometric shape are typical properties of the parallel sensation(s). Replication and symmetry of the percepts are usual. In colored hearing synesthesia, words, voices, environmental sounds, or music trigger the perception of an involuntary photism that is seen outside the body. In a case I called geometric taste (i.e., taste-touch synesthesia) the taste of mint caused subject MW to feel, but not see, a cold, smooth, curved shape in front of him. (MIT)
We often emphasize just two senses, though multi-modal synesthesia also occurs. Individuals mention that a third or fourth sense participates, but "not as often" as the main two that are joined. It is important to distinguish that synesthetic percepts are neither metaphoric nor pictorial: they are concrete, generic, and unelaborated. (MIT)
And Acquired Synesthesia, which is classically seen in temporal lobe epilepsy, head trauma, and mass lesions affecting the medial temporal lobe. Synesthesia may also be induced by sensory deprivation, antiserotonergic hallucinogens such as LSD and peyote, or direct electrical stimulation of subcortical limbic structures. (MIT)
Epileptic synesthesia is a good example of acquired synesthesia; it occurs in 4% of temporal lobe seizures and seems due to the actual electric discharge. Visual, auditory, tactile, gustatory (and, much less often, olfactory) sensations may combine with visceral sensations, vertigo, and involuntary movement, as in these 3 examples:
• A taste of bile, tingling in the left wrist, twitching of the left corner of the mouth, and muscular contractions on the left side of the body
• A lump in the throat, mouth & tongue movements, flashing lights in the right upper fields, a bitter taste
• Hearing the word "five," seeing the number "5" projected externally on a gray background, shooting pains in the right side of the face. (MIT)
Grapheme-color synesthesia is the most common type of synesthesia; it is an automatic, involuntary experience of seeing colors when viewing numbers, letters or words on a printed page (M. Hubbard). The visible shape triggers a secondary visual cue and appears tinged or shaded with a specific hue. In sound to color associations, or chromesthesia, a typical experience is comparable to Disney’s Fantasia, where individual sounds trigger a visualization of color. Lexical-gustatory synesthesia is a particularly rare form of the condition where individual spoken words elicit taste sensations in the individual’s mouth. (E. Dalton, 2013) (de Oleivera)
However, there are many other types of synesthesia. The exact number is not known because there can be so many variations on one sense and its associations. Multiple types of synesthesia are often experienced in conjunction. In fact, it is very common for a synesthetic to have more than one type of synesthesia. Having one type of synesthesia makes you 50% more likely to have a second type (Eagleman and Cytowic, 2009)
Other types of synesthesia include Music/sound – color synesthesia where some people hear sounds and perceive them visually. This can happen with both musical and non-musical sounds. Julian Ashton is an example of a person with music – color synesthesia. When he was a child, he went to the orchestra and experienced a cascade of colors, while others went to enjoy harmonies and the compilation of sounds. Unaware that his experience was out of the ordinary, Julian later reflects on the experience of going to a concert as a child, saying, "I thought they turned down the lights so you could see the colors better."(Real Rhapsody in Blue, 2003)
Lexical-gustatory synesthesia, a lesser-known type of synesthesia is lexical-gustatory synesthesia. This type of synesthesia developed with language acquisition and speakers learn the structure of their native languages. Research has shown that people with lexical-gustatory synesthesia experience a sense of taste when they hear specific phonemes. Often they will taste the type of food that the phoneme resembles. For example, the combinations of the phonemes /I/ /n/ /s/ could cause the taste sensation of mince.(Ward, 2003)
Flavor – Sense of Touch, when someone with this type of synesthesia experiences a strong sense of taste, it can be associated with a sense of touch. Synesthetes may feel different temperatures associated with flavor. For example, a strong, spicy flavor may trigger a feeling of warmth cascading down the arm
Time – space synesthesia, Individuals with this type of synesthesia associate units of time (days, weeks, months, etc.) with places in space, usually related to their body. In addition to having a specific location, the units of time often have shape and color as well. The image above is the way that one synesthetic views the months of the year around his body, starting with dark blue January at the bottom and continuing counterclockwise to the cream-colored December. (Macalaster)
Ordinal-linguistic personification, it’s a variant form of synesthesia in which people assign human characteristics to letters. It is common for this to co-occur with grapheme synesthesia (Simner, 2006). Synesthetes with this type of synesthesia have trouble reading colored text that clashes with the synesthetic color that they experience. (Macalaster)
Individuals within the same category of modality interaction reported differences in their specific associations, although these responses occured from the same stimuli and through the same modality. Yet, consistency within different types of synesthesia provides little insight into the neurological, psychological, cognitive, or perceptual basis of the condition. The patterns or shared experiences between synesthetes merely provide a rudimentary diagnostic tool to distinguish between those with the condition and those without. (E. Dalton, 2013)
Synesthesia is by no means a debilitating condition. In fact, many Synesthetes achieved prominence in their respective fields. Some famous synesthetes include Billy Joel, Vladimir Nabokov, Pharrel Williams, Vincent Van Gogh, Marilyn Monroe and many others.
There’s also another sort of synesthesia that’s called Literary Synesthesia, it is a term that is common in literature, even by authors who don’t have the neurological condition of synesthesia. Literary synesthesia is defined as “a writer’s use of a metaphor of the senses” (O'Malley) , and is not always related to clinical and diagnosed synesthesia. A definitional distinction defines synesthetic experiences as either inter-sense analogy or clinical synesthesia. Only clinical synesthesia is the involuntary dual sensation. In literature, synesthesia is often used as a symbol of pathology, showing that a character has gone through some traumatic brain injury and has come out experiencing the world differently in many different ways.
This neurological condition is not in the forefront of psychiatric or medical investigation, but has been the subject of research for decades (M. Hubbard, 2005). Recently, a study was conducted that examined gray matter structure and functioning in grapheme-color synesthetes through magnetic resonance imaging (Rouw & Scholte, 2010). The resulting images revealed patterns that indicate “partly shared mechanisms for all grapheme–color synesthetes, particularly in posterior superior parietal lobe, which is involved in the integration of sensory information” (Rouw & Scholte, 2010). Despite this persistent research, the neurological mechanism of synesthesia is still largely unknown.
The genetic mechanisms for synesthesia remain equally elusive. In large case studies, samplings indicate little about the exact loci or means through which the condition occurs. Early researchers proposed that the condition may be an X linked trait; however, current research indicates that synesthesia appears to hold no gender bias (M. Hubbard, 2005).Further, according to a study conducted by Edward M. Hubbard, even a pair of monozygotic twins was discordant for synesthesia. (M. Hubbard, 2005)
This condition is entirely distinct from adopted practices such as mnemonic devices or metaphor and from experiences such as hallucination because the neurological phenomena experienced by synesthetes are completely involuntary. Often, synesthetes do not recognize that their behavior is abnormal, because the relation occurs simultaneously between modalities and is often undisruptive if not helpful to their daily cognition. In other words, the experience is unlearned and thus an inherent part of cognition, so the experiences are unquestioned. Nonetheless, there have been reports of some synesthetes experiencing sensory overload, becoming exhausted from so much stimulation. (Baaron-Cohen, Harrison, Goldstein & Wyke, 1993)