Awareness of others is reinforced in such games because careful attention to a partner's actions is a necessity. Mother introduces the game by moving her face in and out of the child's view. Mom looks at the infant with her full face.
Mom looks to the side or looks down.
Mom presents her face again with an exaggerated expression. Mom presents her face close up. Mom pulls her face back. At his stage, it isn't really a game. The infant is more of a spectator, smiling at Mother's antics.