Related abilities
Enjoys playful interactions with others (such as peek-a-boo)
Is vocalizing in response to playful interactions
Is able to play on tummy for longer periods of time
Is able to push up onto forearms and straight arms during Tummy Time
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)