Microsoft aims for AI assistant with personality

Eric Horvitz has - as he puts it - "ate, slept and dreamt" about artificial intelligence ever since he studied the subject at Stanford University in the 1980s.

As managing director of Microsoft Research he has had the opportunity to turn this passion into a reality.

The firm's Redmond campus now has AI-controlled lifts, receptionists and personal assistants in some of its offices.

If reports are to be believed the technology may soon find its way to the firm's Windows Phone platform.

In an exclusive interview, Mr Horvitz tells BBC technology reporter Leo Kelion about the challenges involved in creating a natural-sounding virtual helper.