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Since his original paper, Turing had considerably broadened his thoughts on thinking machines. He now proposed the idea that a machine could learn from and thus modify its own instructions. In a famous 1950 article in the British philosophical journal Mind, Turing proposed what he called an "imitation test," later called the "Turing test." Imagine an interrogator in a closed room hooked up in some manner with two subjects, one human and the other a computer. If the questioner cannot determine by the responses to queries posed to them which is the human and which the computer, then the computer can be said to be "thinking" as well as the human.
Turing remains a hero to proponents of artificial intelligence in part because of his blithe assumption of a rosy future: "One day ladies will take their computers for walks in the park and tell each other, 'My little computer said such a funny thing this morning!'"
Unfortunately, reality caught up with Turing well before his vision would, if ever, be realized. In Manchester, he told police investigating a robbery at his house that he was having "an affair" with a man who was probably known to the burglar. Always frank about his sexual orientation, Turing this time got himself into real trouble. Homosexual relations were still a felony in Britain, and Turing was tried and convicted of "gross indecency" in 1952. He was spared prison but subjected to injections of female hormones intended to dampen his lust. "I'm growing breasts!" Turing told a friend. On June 7, 1954, he committed suicide by eating an apple laced with cyanide. He was 41.
TIME senior writer Paul Gray writes on a Turing machine