At first glance, the online game appears straightforward. Inside a virtual restaurant you play either a waitress trying to squeeze a tip out of her customer or a ravenous diner.

Behind the scenes, though, every move you make and word you utter is being recorded. Your responses will be used to teach virtual characters how to behave more like real people.

Most research in the games industry has focused on generating cinema-quality graphics at the expense of characters' speech and behaviour, says games developer Jeff Orkin, who is a student in the Cognitive Machines group at the Massachusetts Institute of Technology. This is because their reactions are pre-programmed, leaving them unable to respond to unpredictable situations. "Wooden would be a complimentary term," says Orkin's supervisor Deb Roy.

The Restaurant Game (http://therestaurantgame.net) has been designed to change this. Participants act out their roles and chat by typing words that immediately appear on the screen.

Roy and Orkin will then feed this information into software designed to learn how characters react to specific situations. After training the software on thousands of examples, the pair will use it to develop a second game they are working on, also based on a restaurant scene. The software's new-found knowledge will help it govern how characters behave in similar situations. "You give characters goals and they work out how to achieve them," says Roy. The game has been played around 1600 times since its launch in February.