Research on collaborative learning is currently a very popular topic in education, psychology and computer science. In recent years educational research has attempted to determine under what circumstances collaborative learning is more effective than learning alone. More recently, numerous studies have focused on computer-mediated collaborative learning. In psychology, the interest in collaborative learning is related to the emergence of new theories such as 'shared cognition' and "distributed cognition". These theories move away from the traditional view conveyed in cognitive science following which human cognition is bound inside individual heads. Cognition in general, and learning in particular, are viewed as the emergent properties of a group of individuals and their surroundings, namely the artifacts which come into play. Particular attention has been paid to computers as communicative and cognitive artifacts. Finally, the word "collaboration" is also used very frequently in computer science for describing the interactions among artificial agents.