A very common request that we get is people want to practice conversation, said Duolingo's co-founder and CEO, Luis von Ahn. The company originally tried pairing up non-native speakers with native speakers for practice sessions, but according to von Ahn, "about three-quarters of the people we try it with are very embarrassed to speak in a foreign language with another person."
In 1950, Alan Turing's famous article "Computing Machinery and Intelligence" was published, which proposed what is now called the Turing test as a criterion of intelligence. This criterion depends on the ability of a computer program to impersonate a human in a real-time written conversation with a human judge, sufficiently well that the judge is unable to distinguish reliably—on the basis of the conversational content alone—between the program and a real human. The notoriety of Turing's proposed test stimulated great interest in Joseph Weizenbaum's program ELIZA, published in 1966, which seemed to be able to fool users into believing that they were conversing with a real human. However Weizenbaum himself did not claim that ELIZA was genuinely intelligent, and the introduction to his paper presented it more as a debunking exercise: