In AI, Blackboard systems are comprised of a central global workspace, and a collection of software agents which act upon it. Agents are primed to act by other agents or by features on the blackboard. The agents work together to solve the problem. Famous examples are the Hearsay-II speech recognition system and Douglas Hofstadter's Copycat and Numbo projects. The blackboard architecture appears to resemble human cognition and is often proposed as a Cognitive Science model.