Mirror writing is formed by writing in the direction that is the reverse of the natural way for a given language, such that the result is the mirror image of normal writing: it appears normal when it is reflected in a mirror. It is sometimes used as an extremely primitive form of cipher. The most common modern usage of mirror writing can be found on the front of ambulances, where the word "AMBULANCE" is often written in very large mirrored text, so that drivers see the word the right way around in their rear-view mirror—and understand why they hear a loud siren behind them.
Research suggests that the ability to do mirror writing is probably inherited and caused by atypical language organization in the brain. It is not known how many people in the population inherit the ability of mirror writing (an informal Australian newspaper experiment identified 10 true mirror-writers in a readership of 65,000). Half of the children of people with the ability inherit it. There are more left-handed mirror writers than right-handed ones, probably because left-handed people tend to have atypical language centers in their brain. 15% of left-handed people have the language centres in both halves of their brain. The cerebral cortex (thin layer of dense brain cells covering the whole brain) and motor homunculus (relates to voluntary movement) are affected by this causing them to be able to read and write backwards quite naturally.Template:Citation needed
Leonardo da Vinci wrote most of his personal notes in mirror, only using standard writing if he intended his texts to be read by others. The purpose of this practice by Da Vinci remains unknown.
Matteo Zaccolini may have written his original four volume treatise on optics, color, and perspective in the early 17th century in mirror script.
Mirror writing calligraphy was popular in the Ottoman Empire during the 18th and 19th centuries among the Bektashi order, where it often carried mystical associations. The origins of this mirror writing tradition may date to the pre-Islamic period in rock inscriptions of the western Arabian peninsula.
In some rare forms of dyslexia, a person suffering from dyslexia has the ability to read and/or write, but only in the styles of mirror writing.Template:Citation needed
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- News in Science - Mirror writing: my genes made me do it - 02/06/2004
- Library of Congress image bibliographic data. Retrieved 19 January 2009.
- Mirror Writing a genetic trait
- "Acquired mirror writing and reading: evidence for reflected graphemic representations" by Jay A. Gottfried, Feyza Sancar, Anjan Chatterjee 
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