READING, England: Computers argued, cracked jokes and parried trick questions, all part of an annual test of artificial intelligence carried out at the University of Reading.

Typing away at split-screen terminals, a dozen volunteers carried out two conversations at once on Sunday: one with a chat programme, the other with a human. After five minutes, they were asked to say which was which. Some were not sure who or what they were talking to.

There was one time when I was speaking to the two, and there was an element of humor in both conversations. That’s the one that stumped me more than others,” said Ian Andrews, one of the judges in Reading, just west of London.

Transcripts of the conversations showed some savvy judges ruthlessly trying to trip programs up with questions about the day’s weather, the global financial turmoil and the color of their eyes.

Blue, of course!” answered Eugene Goostman, a chatbot” designed by Pennsylvania-based programmer Vladimir Vesselov. Eugene was one of five programmes competing to pass themselves off as flesh and blood. A sixth programme, Alice, dropped out when it could not be set up in time. Fred Roberts’ Elbot scooped the day’s top award: the Loebner Artificial Intelligence Prize’s bronze medal, for duping three out of 12 judges assigned to evaluate it.

The contest draws on the ideas of British mathematician Alan Turing, who came up with a subjective but simple rule for determining whether machines were capable of thought.