It may be an old fantasy, but the basic premise that we will one day engineer machines that are at least as smart as us and whose behaviour is indistinguishable from ours is, according to many roboticists, closer to reality than we might like to think. Our understanding of the human brain, and our ability to 'reverse engineer' it - to analyse how it works and replicate its processes - is increasing dramatically, such that within a couple of decades we should know all about the mechanics of human intelligence and, crucially, learning, and be able to apply this to machines.