Final answer:
The ability to understand compromise in social play interactions varies depending on a child's cognitive development, starting around 4 years old.
Step-by-step explanation:
The ability to understand the concept of compromise as related to social play interactions can vary depending on the child's cognitive development. Around 4 years old, children can begin to cooperate with other children and share when asked, which shows some level of compromise. By 6 years old, children can identify themselves in terms of group memberships and compare themselves to their peers, which further develops their understanding of compromise. However, it is important to note that the ability to reason and understand compromise may vary considerably among children.