Published 28 Dec 2016

Synesthesia refers to a neurological Phenomenon where by stimulation of a cognitive pathway or one sensory result to inventory experiences automatically in a second cognitive or sensory pathway. Synesthetes are the kind of people who experience such kind of problems. The neural basis synesthesia theory began after the observation of some dedicated parts of the brain being specializing to particular functions. This led some researchers to suggest that increase in brain cross-talk between several zones made for different functions would result to different types of synesthesia (Rader, Tellegen, 1987, p.983).

For instance, the extra experience of viewing colors when observing graphemes might result because of “cross-activation” of V4 which might subsequently arise because of the normal developmental process of pruning failure. The reason for this is that regions that are engaged in identifying letters and numbers are next to an area engaged with color processing,V4.

In color –graphemic synesthesia, which is one type of synesthesia, numbers as well as letters are seen as inherently colored while in Ordinal linguistic personification, numbers, days, weeks and months evoke personalities while in the same numbers, days, weeks and months would be perceived as elicit exact positions in space in number form synesthesia or spatial- sequence Visual motion and sound shnesthesia are newly identified types that include hearing sounds in regard to flicker and visual motion. There are more than sixty types of synesthesia that have been reported by different people but only a small number of such cases have been studied by scientific investigations. In one type, the perceptions of synesthesia have different intensity.

People possess different synesthetic perception awareness. Synesthesia is estimated to be prevalent in one out of every twenty three persons in its variants. Although it runs firmly in families, the exacted mode of inheritance is not yet established. It is also reported by persons who are mainly influenced by psychedelic drugs, during temporal lobe epilepsy seizure, after stroke, or as impacts of deafness or blindness. This kind of synesthesia is commonly referred to as “adventitious synesthesia” which is different from more usual congenital types of synesthesia.

Adventitious synesthesia that comprises of stroke and drugs (but not deafness or blindness) usually includes sensory linking like sound, touch or vision and hearing. Culture related synesthesia and learned sets like graphemes, lexemes, months of the year or days of the week cases are usually reported in fewer numbers. (Dudycha, Dudycha, 1935, p. 59)

Although, sometimes referred to as “neurological condition”, synesthesia is not regarded to be in either DSM-IV or the ICD groupings. This is because it does not interfere with the usual daily working. Most synesthetes claim that they are either experiencing neutral or even pleasant conditions. Synesthesia, just like perfect pitch or color blindness, is a difference in experience of perception which is reflected by the Neurological condition. Up to the current time, there has been no consistent link between synesthetic experience and other psychiatric or neurological conditions.

Initially synesthetic experiences were assumed to be different from synesthetes, but of late research has indicated that the two have some underlying similarities which can be seen if big numbers of synesthete are studied together. For instance, sound-color synesthesia makes one see lighter colors for higher sounds and Graeme –color synesthesia have significance likeness for each of the letters color. Different people do report for different triggers as well as different experience intensities for their circumstances in forms of synesthesia. This indicates that the inpidual definition of synesthesia is challenging and many synesthetes don’t know that they have a name for their experiences in synesthesia. In spite of this difference between inpiduals, synesthesia is defined by some few common elements.

Most of the synesthestes usually report that they had no idea that they had experiences which were unusual until they knew that others had not posses them. Other people report feeling that they have been possessing in their whole life and how they found out they had them in their childhood. This consistent and involuntary makes synesthesia to be seen as an experience. Only a few cases of synesthetes have reported their experience to be resulting from a certain level of sensory overload. There are numerous autobiographical notes and self reports by interviews and synesthetes which indicates a big number of varieties of forms of synesthesia, synesthesia perception intensity, the manner in which they make use of their synethesia in work and in daily life as well as the awareness of the difference in understanding the physical world from the others (Marks, 1975, p.305).

Synesthesia can arise from any two perceptual modes or senses. With a big number of types of synesthesia, there have been an adopted convection of showing the forms of synesthesia by use of notation x and y, with x being the “inducer” or trigger experience while y is the “concurrent” or additional experience. For instance, seeing numbers and letters as being colored would be labeled as grapheme color synesthesia. Equivalently, tone (color, movement) synesthesia would mean that the synesthetes perceive colors and movements due to hearing musical tones.

In grapheme, color synesthesia, graphemes (inpidual letters of the numbers and alphabets) are tinged or shaded with a certain color. Research on large numbers of synesthesia indicates that there are commonalities with letters. For instance, A is likely to be seen as being red, although synesthetes do not report the same color for same letters.

Synesthetes experience colors regarding tones and other sound aspects in sound, color synesthea. This kind of synesthea has two categories namely; narrow and broad band sound, color synesthea. Narrow band sound, color synesthea (music, color synesthea) has music stimuli such as key or timbre that indicates a certain color experiences in a manner that a specific note elicits red or harps elicit the experiencing of viewing a golden color. Several environmental sounds such as alarm clock or a closing door might elicit visual experiences.

Changes of colors in regard to different sound stimuli aspects involve more than one hue of color. Color dimension experiences do vary. For instance, brightness, which is the amount of white in a certain color, when extracted from red color, makes it fade into a brown and eventually to black color. Color saturation (intensity) varies with the colors, medium blue and fire engine red, for example are regarded as highly saturated while other colors such as white, grays and black are seen as unsaturated. In addition to this, music, color synesthetes usually claim the colors to be moving or streaming into and out of their view area. Some music, color synesthetes hold that a certain tone will possess a particular color.

With study of large samples, consistent trends are experienced, in a way that notes with higher pitches are seen to be more brightly colored. This equivalent patterns of brightness in pitch matching in objects which are not synesthetic indicates that this synesthesia type have common mechanisms with non-synesthetes (Rader, Tellegen, 1987, 985).

In Ordinal-linguistic personification, ordered sequences like Ordinal numbers, months, days as well as letters are linked to personalities. For instance, “T” is usually associated with ungenerous, crabbed creatures. U is linked to soulless sort thing while 4 is seen as being honest, 9 is dark, gentleman, tall and graceful and 3 is untrustworthy.

Lexical gustatory synesthesia is an unusual form of synesthesia where single words and phonemes of the language spoken normally evoke the mouth taste sensations. Lexical gustatory synesthetes would experience immediate and involuntary taste sensation on their mouth when they hear of some words such as read or inner speech words or word sounds. This particular taste does not change; it has remained in that form for along duration. Research have indicated that, lexical-gustatory synesthesia links with someone’s early experience with food.

Some people have no synesthesia experiences of certain foods despite them consuming them frequently in their mature lives (Marks, 1975, p.309). Some of these early food experiences are associated with tastes regarding the name of the word. Semantic influences happen to be another source of tastes in which names of different foods tend to have a taste of the food they match. For example “blue” tastes “inky”.

It is not difficulty to find out if someone is a synesthete as it is hard to fake. The easiest testing includes reliability of test-retest for a long duration of time. Synesthestes usually perform highly than non-synesthetes. They can scores about 90% over test-retest intervals in a period of one year with non-synesthestes obtaining as low as 30-40% under the same conditions even with warning of testing. Complex tests involve the use of modified versions of the Stroop effect that utilizes Stroop paradigm.


  • Dudycha, G. J., & Dudycha, M. M. (1935). A Case of Synesthesia: Visual Pain and Visual Audition. Journal of Abnormal and Social Psychology, 30, 57-69.
  • Marks, L, E. (1975). On colored-hearing synesthesia: Cross-Modal Translations of Sensory Dimensions. Psychological Bulletin, 82, 303-331.
  • Rader, C. M., & Tellegen, A. (1987). An Investigation of Synesthesia. Journal of Personality and Social Psychology, 52, 981-987.
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