When Google's AlphaGo program beat grandmaster Lee Se-Dol four games to one, both programmers and professional Go players were surprised. The general consensus was that it would be years before a computer could defeat a human at the complex board game, which players describe as requiring elegance and imagination. Director of the MARCS Institute for Brain, Behaviour and Development and electrical engineering professor, Jon Tapson, said AlphaGo's victory was cause for a re-evaluation of how we use artificial intelligence (AI). "They could find ways of manipulating the stock market -- maybe by buying and selling shares in rapid succession to create the illusion of a change in market sentiment," he said. He said unless there was reason to go looking, it was unlikely humans would notice that kind of behaviour, and that it would be difficult to program or regulate the actions of an AI if we do not know how it makes decisions.