Why can’t computers think?

With increasingly advanced computers being developed all the time Artificial Intelligence is no longer the reserve of science fiction novels. However, it has so far remained impossible to develop a computer which can fool humans into thinking it is also human. It’s thought processes have not lacked complexity but what is it that sets human thought apart from that of a computer?

In 2009 the Leobner Competition asked people to enter into a conversation to see if a computer could fool the judges into thinking it is human through its replies. This competition will be contested at the end of the week in Brighton. Click here for the link to an interview with last years winner.
What questions would you ask to decide whether the responses you were getting were computer generated? How would you decide?

To read the article and blog forum in the Guardian ‘Why can’t computers think?’ click here