Answer: Intersubjectivity
Explanation: The term Intersubjectivity could simply referred to as agreement. The ability of members of a group or sociocultural group to concur or agree on a particular course is explained in the theory of Intersubjectivity. Intersubjectivity theory explains the understanding or coherence shared among members of a particular such that they all reason and attach the same meaning or conclusion to a particular situation.
In the scenario above, the inability of members of the 4-years old playgroup to agree on defining a set of rules guiding their game play and consequent ability of 6-years old playgroup members to successfully agree on a rule definition hughlights the sociocultural theory of Intersubjectivity.