Related abilities

Enjoys playful interactions with others (such as peek-a-boo)

Is vocalizing in response to playful interactions

Maintains eye contact with familiar people during playful interaction (4-6 months)

Is usually happy when not hungry or tired (4-6 months)

Is not upset with everyday sounds (4-6 months)

Does not demonstrate frequent or long bouts of being upset (4-6 months)