Why babies smile

Newborns: brief and can occur during sleep

 3-8-week: smile to external stimuli

 6-week to 3-month: social smiles (directed to people)

 4-month: smile in response to familiar others’ smiles

 7-month: smiles more to familiar people

 12-month: different smiles in different situations and to

different people (open smile, laughs, reserve smiles)