Imagine what it must be like for an infant meeting new people for the first time. You're sitting there completely unaware of the influx of people you are about to meet. One by one faces float in and out of view. Some look like mom, some look like dad. Some are loud, some talk softly. All you know is that there are a lot more people around, but little by little you're getting the hang of it. Faces become more familiar as time goes on. You even start to get excited when you see a face you know like grandma or grandpa.
At about three months, babies will begin to recognize faces completely, so it's not just your imagination when you see your baby's face light up when you walk into a room. How does she know it's you? Well, you've been the main face she's been looking at since birth during feeds, cuddles, and lullabies. This is now based purely on your face, where before your baby might have recognized you by your voice or smell.
I remember the first time I realized that my son truly knew who I was. It wasn't just my voice that made him happy; it was also my face. He knew me. All I had to do was peek in on him, and he would smile from ear to ear and wiggle his whole body. If I walked away, his eyes would follow me from one corner of the room to the next. He couldn't take his eyes away from me. Soon, he would start reaching for me.
Don't get me wrong, he also recognizes dad and few other people like grandma and grandpa, but there's just something special about a boy and his mama.