What is ACT-R?
ACT-R is a proposed unified theory of cognition realized as a production system. It is a unified theory of cognition, in the spirit proposed by Newell (1990, Unified theories of cognition, Harvard, Cambridge, MA), in that it is designed to predict human behavior by processing information and generating intelligent behavior itself. The ACT-R architecture integrates theories of cognition, visual attention, and motor movement. It has been applied successfully to model higher-level cognition phenomena, such as working memory, scientific reasoning and skill acquisition, to name but a few. Recently, it has been applied successfully to a number of HCI issues. ACT-R makes a distinction between two types of long-term knowledge, declarative and procedural knowledge. Declarative knowledge is factual and holds information like ‘2 + 2 = 3’. The basic units of declarative knowledge are chunks, which are schema-like structures, effectively forming a prepositional network. Procedural knowledge consist
