These days, the bots playing poker can't bluff convincingly. "Computers are programmed to perform the best strategy, but bluffing is based on unexpected, illogical actions," says Evan Hurwitz, a computer scientist at the University of the Witwatersrand in South Africa.

Now Hurwitz and Tshilidzi Marwala, also at Witwatersrand, have developed a virtual player that has taught itself to bluff at a card game called lerpa. Their artificial intelligence bot, named Aiden, is based on a neural network algorithm that usually forecasts stock market fluctuations.

Then the researchers decided to play Aiden against three other similarly trained bots to see what would happen. "They began to develop their own personalities - either aggressive or conservative - depending on their past successes,"