Game developer Rollo Carpenter tells the BBC's Chris Vallance about the AI interrogation techniques written into the free online game 221b. He has programmed it to recognise a large number of potential questions that gamers could ask characters in the Sherlock Holmes game. The aim is to make characters respond in the way humans do, rather than requiring precisely-worded questions. Mr Carpenter has developed an array of artificial intelligence software. He set up the 'chatbot' site www.cleverbot.com, which attempts to respond to questions in as human a manner as possible. He has also won several competitions aimed at outwitting humans into believing they are not talking to a computer.