1. the interaction between two or more people working on a task that allows greater learning to be achieved, particularly by those who are less skilled, than would occur if the participants worked alone.

2. the third stage of cultural learning, in which two or more individuals who are equal in expertise or authority work together to solve a common problem. See also imitative learning; instructed learning. [proposed by U.S. psychologist Michael Tomasello (1950–  ) and colleagues]