
2 MONTHS: Smiles at you. By now, your baby will aim his first social grins (not the gas-induced ones) at faces that are becoming familiar, like yours.
4 MONTHS: Imitates you. Pucker up or stick out your tongue and he may try to mimic your moves, a reflex that becomes more intentional as he figures out that you love it. The more animated you get, the more he'll copycat.
7 MONTHS: Raises his arms to be held. Once he has the motor skills to grab for his favorite toys, he'll start grabbing for you, too.
8 MONTHS: Wails when you hand him over to the babysitter. Yes, it's heartbreaking, but separation anxiety shows he prefers you to others.
11 MONTHS: Says "mama." The combination of easy-to-make sounds and a desire to name what's important to him means "mama" is often among babies' earliest words. (Try not to worry, though, if "dada" or even "dog" comes first!)
12 MONTHS: Gives you a kiss. Around his first birthday, your baby finally has the motor and communication skills to respond to your smooches. His won't be perfect -- he may forget to close his mouth -- but no matter what, those first efforts show that he thinks you're pretty special.
http://www.parenting.com/article/how-babies-show-their-love