The first documented success was the system MYCIN in the mid-1970s, which beat expert human performance on diagnosing blood infections: http://en.wikipedia.org/

The first documented success was the system MYCIN in the mid-1970s, which beat expert human performance on diagnosing blood infections: http://en.wikipedia.org/wiki/Mycin http://en.wikipedia.org/wiki/Mycin I can't seem to find the paper I'm thinking of in some quick Google Scholar searching, but I believe there was a follow-up article that looked into why such a fairly simple system was able to beat humans, when it clearly lacked the range of expertise of the human experts (and was entirely missing information on some real conditions). The paper, if I'm remembering correctly, concluded that the win was almost entirely due to one specific failing displayed by the humans (even expert specialists) but not shared by computers: very bad intuition for conditional probabilities.