the group performance depend upon the individual performances of its participants and the ways in which those participants communicate?

This question is given new light by recent trends in cognitive psychology, which after a half a century of fascination with isolated cognition in the individual, has finally admitted the individual interaction with the social environment. It is increasingly understood that joint actions and joint cognition are not limited to situations of committee/voter decisions, but instead, they pervade everyday life and require the constant coordination and integration of cognitive and physical abilities. This new approach, typically called [*distributed cognition*]{} [@Hutchins1995cognition], or [*extended cognition*]{} within the social domain [@Clark2006], brings the focus of research to the mechanisms of cognitive and physical coordination [@Kirsh2006] that affect this integration. It also brings attention to the comparison of the performance of the group to the performance of the individual. For some tasks that require different types of knowledge and abilities from group participants, groups are likely to outperform individuals [@Hill1982]. For other tasks, such as simple discrimination tasks or estimations, a question arises if a group is indeed better than the best of its members. If there are such situations, it is important to know 