As a newborn, your baby will be able to recognize her parents' voices and the voices of other people that surrounded her mother during pregnancy, from siblings (if she has them) to the cast of her mother's favorite television show. She will also be sensitive to the feelings of others, particularly her mother. She'll notice if mom is feeling tense and will quickly become tense herself. (You may come to believe that your baby will wake up on cue if you even think about having sex with your husband.)

By four to eight weeks your baby will probably be actively smiling in response to things that make her happy. Around two months she will probably turn her head in the direction of a parent's voice and spend many happy moments gazing directly into your eyes.

You'll hear her first laugh when your baby is around four months old, and will put yourself through all sorts of crazy antics trying to get her to repeat it. Also around four months, you'll be able to tell when she's excited — she'll squeal, wriggle, or breathe heavily.

At around six months another emotion will emerge: anger. You'll discover that your baby's angry cry is much different from her tired or hungry cry. This one won't be as much fun for you as joy and excitement, but it's an important one for your baby because anger is motivating. A child who is mad that her favorite toy has rolled out of reach is motivated to wriggle over to it, developing her motor skills. Around the same time your baby will also begin to recognize the difference between an angry voice and a friendly voice, and react accordingly.