Figure 1

Illustration of the theoretical Dunbar Circle in ego networks. The square in the center represent the ego and the circles around are the alters, who have direct connection with the ego. The circle size is proportional to the emotional closeness between the alters and the ego. According to the emotional closeness, the alters form a hierarchical structure with different layers in which their closeness to the ego decrease from inner layer to the outer layer. The theoretical Dunbar Circle corresponds to a four-layer hierarchical structure with the cumulative number of 5, 15, 50, and 150 from inside to outside