Related abilities

Is able to laugh or giggle when they find something amusing

Shows interest in their own hands

Enjoys toys with more complex patterns and shapes

Experiments with cause and effect e.g. shaking a rattle and realizing it makes noise

Is able to hold and shake toys

Is not upset with everyday sounds

Is usually happy when not hungry or tired (2-4 months)

Does not demonstrate frequent or long bouts of being upset (2-4 months)