Related abilities
Is interested in interacting with others, e.g. peek-a-boo (9-12 months)
Maintains eye contact with people during playful interactions (9-12 months)
Turns head in response to name being called (9-12 months)
Has grown accustomed to everyday sounds and is usually not startled by them (9-12 months)
Is generally happy when not hungry or tired (9-12 months)