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Alan Turing

From CAPTCHA to morphogen: how Alan Turing has influenced modern English

Alan Turing was a 20th-century mathematician and computer scientist, most famous today for his cryptanalysis work during World War II in which he and others at Bletchley Park broke the German Enigma ciphers and created the first electronic computers. But his influence stretches far beyond that achievement, into the English language and even into the modern gay pride movement. Turing’s name appears in several words in our dictionaries relating to his work in the computer science and artificial intelligence fields.

We have the technology

The Turing machine, ‘a mathematical model of a hypothetical computing machine which can use a predefined set of rules to determine a result from a set of input variables’, was described by  Turing himself as part of his 1936 paper On computable numbers, with an application to Entscheidungsproblem, published in the journal Proceedings of the London Mathematical Society. A Turing machine is not a physical computer – no electronic digital computer yet existed – but a theoretical model that can be used to describe the operation of any physical computer. Even some seventy years later, it is still one of the foundations of computer science.

The Turing test, ‘a test for intelligence in a computer, requiring that a human being should be unable to distinguish the machine from another human being by using the replies to questions put to both’, is commonly regarded as the barrier which a computer program must break to be considered an artificial intelligence. Though he didn’t use the word himself to describe it, the test was set out by Turing in his 1950 paper Computing machinery and intelligence, published in the journal Mind. Try ELIZA, a real example of a Turing test.

A CAPTCHA is a much newer creation, and is defined as ‘a computer program or system intended to distinguish human from machine input, typically as a way of thwarting spam and automated extraction of data from websites’. It is an acronym, from ‘Completely Automated Public Turing test to tell Computers and Humans Apart’, and even if it sounds unfamiliar, the chances are you have probably completed one if you have ever been required to decipher a distorted piece of on-screen text when signing up for an online service.

A legacy in lexicography…

Turing is cited in eight Oxford English Dictionary entries, but he is only the source of the first quotation for one of them. Morphogen, a word which reflects his interests beyond the mathematical and computing fields, is ‘A chemical agent which is or may be capable of bringing about or determining morphogenesis’.

1952   A. M. Turing in Philos. Trans. (Royal Soc.) “These substances will be called morphogens, the word being intended to convey the idea of a form producer. It is not intended to have any very exact meaning.”

Of course, a lexicographer’s work is rarely done. Turing may only be the first citation of one entry so far, but there is every chance that he will be cited more as new entries in his particular field are researched and published.

…and beyond

Turing is held in very high regard by those of us for whom computing is a passion and a career – he is one of the originators of our art. But there is another field in which he is honoured: the gay community. As a homosexual living in an age in which homosexuality was a crime, he was prosecuted and forced to undergo chemical castration. Two years later, in 1954, Turing is thought to have committed suicide by ingesting cyanide. He was undoubtedly a victim of anti-gay prejudice and in 2009 the British government offered a posthumous public apology for the way Turing was treated. One of the better-known memorials to Turing is a statue of him sitting on a bench in Manchester’s Sackville Park, adjacent to the city’s gay quarter and a part of the university in which he worked.

This centenary year is being marked by a number of events worldwide that will celebrate Turing’s life and achievements. If you are interested in learning more, you can find further details on the Turing Centenary Advisory Committee website.

Image by: User Lmno on en.wikipedia (Photograph taken by Lmno) [GFDL ( or CC-BY-SA-3.0 (], via Wikimedia Commons

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