Your Baby from 4 to 6 Months: Personality!

By the fourth month, life with your new baby is gradually becoming less hectic. Perhaps you've even settled into a routine. Although there may still be an end-of-day fussy period, babies who were colicky are likely to be more peaceful, and even restless babies may be letting their parents sleep for six hours at a stretch.

Now the fun can really begin. Pediatrician Stanley I. Greenspan, MD, author of Building Healthy Minds (Da Capo Press), likens this stage of life with a baby to "falling in love," because by 4 months infants can begin giving back as much love as they receive. They are no longer simply crying or smiling, asleep or awake, but expressing complex emotions as they develop relationships with the people who care for them.

During the first few months of life, your baby's moods might have been dictated by the presence of gas bubbles or hunger pains, and whether her need to be comforted was being satisfied at the moment or not. Now, at 4 months, life is about more than sleeping and eating. Her brain development (and the fact that her digestive and neurological systems are more regulated) allows her to take a greater interest in the world and feel emotions like frustration, fear, curiosity, and enthusiasm. (Doctors can detect the first signs of anxiety and depression as early as 3 or 4 months.)

A stable, secure relationship with a loving caregiver is the best predictor of normal development in infancy. By now she has learned to associate the sight of you with pleasurable feelings, and she will respond accordingly as you round the corner of her room to pick her up from her crib. "Her eyes will light up as soon as she sees you, she'll give you a big smile, and it will be clear that she's delighting in your touch," says Dr. Greenspan. She may further demonstrate her pleasure in your company by moving her mouth, arms, legs, or whole body in rhythm with your speech, gazing raptly into your face, and answering your voice with gleeful sounds of her own even if she can't see you.

"You'll know that your baby has reached a new rung on the developmental ladder when she reacts to your emotions with her own," says Dr. Greenspan. Good indications that your baby is forming a close attachment to you include smiling back when you smile at her, relaxing when you hold her, cooing when she's touched or spoken to, and looking uneasy when you have to leave her.

Why is it possible for your baby to become more actively engaged in a relationship with you now, and not before? In addition to being better able to regulate her own bodily functions, from breathing to eating to sleeping, your baby's vision has improved, her sleep-wake cycles are more in sync with yours, her attention span is longer, and she's discovering that she can make things happen -- like flashing a smile and having you smile back.

Your job is to introduce your baby to the world, and the world to him. You will be his companion and guide, giving him the confidence to test out his curiosity while reassuring him that he is loved and safe no matter what his mood.

One of the most miraculous accomplishments during this second stage of infancy is your baby's ability to vocalize his emotions. During his earliest weeks of life, crying was the only way he could get your attention. By four months, most babies "become eager communicators," says Dr. Greenspan. He may start "talking" by babbling open vowel sounds, like "aah" and "ooh." Gradually, as he experiments with using his teeth, tongue, and vocal cords, he'll make lots of funny noises, blow raspberries, and add consonants to his repertoire of sounds. The first are generally p, b, and every mother's favorite, m, so that it might sound like your baby is calling "Ma-ma!" Dads may feel disheartened not to hear "Da-da," but this is just a function of speech development -- sounds that require the tongue and muscles deeper in the mouth come later.

This babbling isn't just a random collection of sounds but repeated attempts by your baby to move her lips, tongue, and jaw to make the same sounds she hears. By the time your baby hits the half-year mark, she will have heard hundreds of thousands of vowel sounds, developing a sort of "sound map" in her brain that helps her hear and repeat those sounds more clearly in the future, according to University of Washington researcher Patricia K. Kuhl, PhD. What's more, as an infant repeatedly hears his native language, he develops perceptual strategies increasingly dedicated to processing this particular language. For example, in early infancy, your baby may hear sounds in other languages that we cannot even detect. But as the months wear on and he tunes in to the rhythms and patterns of his own language, he stops hearing the sounds that he doesn't need to replicate so that he can focus better on the ones he really needs to know.

How can you ensure that your baby is learning language, if she is not actually speaking any words? Again, relationships are key. Not surprisingly, researchers have found that infants of 4 to 6 months who have people speaking to them frequently are apt to learn language faster than those who don't. Talk to your child often, and listen when he talks to you. There's no need for tapes or fancy learning gadgets; you can look at a book together and talk about the pictures, tell him your plans for the day as you change his diaper, and point out interesting sights as you go for walks in the stroller.

"The most stimulating experiences for young babies come from human interaction," stresses Joshua Sparrow, MD, a child and general psychiatrist at Harvard Medical School. "Nothing else can equal the complexity of the human voice or body language."

Now that your baby is out of that fussy newborn phase and more alert and responsive, you can start looking for clues as to what type of baby you have, as his unique personality begins to emerge. Child development experts use nine basic traits, which are inborn, to describe temperament. Some of the easier ones to discern in babyhood include regularity (whether he tends to be hungry and sleep at the same time every day), adaptability to change, sensitivity, activity level, and distractibility. For example, if you have a sensitive baby, he's more likely to become overstimulated by noise and lots of people around him. A less sensitive baby may be the life of the party as he's passed from one adoring relative to another. To assess your baby's temperament, keep track of his reactions to daily routines. Does he relax in his infant seat, or kick his legs nonstop? Does he cry when the smoke alarm goes off, or is he just curious? Then you can tailor your parenting style accordingly -- and discover how best to have fun with him and deepen your relationship.

One key milestone of physical development between 4 and 6 months is the fine-tuning of your baby's ability to see the world around him. Compared with touch, taste, and smell, vision is a relatively primitive sense at birth; it is the only one of our five senses that gets no stimulation in the womb. But that's all right. A newborn doesn't need more than limited vision to begin learning to recognize the faces in his family or to see his own hands in front of his face. However, by 6 months of age, your baby's vision will develop to the point where he has depth perception, color vision, and well-controlled eye movements -- just as his increasing motor skills give him the ability to play with his own hands, kick at his mobile, touch his body or your face, or reach out and grab the objects you place in front of him.

Another new development: His improved vision will let him see the pattern formed by your face and recognize you from a distance. (Initially, he could see your nose, mouth, and eyes only as isolated features -- now she's putting it all together as "Mommy.") Of course, it's not just your face he can see at a distance. There are all sorts of other interesting things to look at, which means baby might get distracted. Just when you think your baby has settled to nurse, for instance, he pulls away from your breast to gaze around the room. This behavior causes some mothers to worry that their babies aren't eating enough at this stage, says Joshua Sparrow, MD, coauthor of the parenting series The Brazelton Way (Da Capo Press), or to perceive this lack of interest in feeding as a sign that their baby is ready to wean. Neither is true. "What happens at 4 months is that your baby can now take in a wider range of visual experiences," he says. So your baby may turn his head to follow his brother running across the room, or he might catch a flash of his grandmother's red sweater out of the corner of his eye and have to find out what she's doing. You may have an easier time nursing if you do it in a quiet, dimly lit room. If you are patient and talk with your baby about what he's seeing, and let him look to his heart's content, you will help him understand the world and improve his vision even more; when you allow him to look at different things, you are actually encouraging electrical activity between his brain cells, thus boosting his brain power.

Between 4 and 6 months, most babies start taking charge of their own actions. They will raise their head when lying face down, until eventually they can bear their weight on their arms and do a few push-ups. Your baby will suck on her toes to see how they taste, and she'll be so delighted by the sensation of a soft blanket on her skin that she may pull it across her face. She'll begin reaching for toys by 4 months -- though it's still easiest to hold them with two hands -- and by 6 months, she'll have the dexterity to grasp a plaything, examine it carefully, mouth it for texture and flavor, and transfer it from one hand to the other. When your baby wants a different toy, or even a different view, he may roll over and creep forward (or backward by mistake!) as he propels himself on his belly in a stealthy soldier move. At 4 months, too, your baby will be delighted to be propped up in a sitting position against some pillows, allowing him to see the world from a different vantage point while building muscles in his core. He will grow increasingly more stable until by 6 months he will have the coordination and muscle strength to sit alone if put in that position.

• Month 4: Reaches for objects; coos and babbles
• Month 5: Rolls from front to back; shows emotions through expressions, body language
• Month 6: Vision is fully developed; sits up without support

Holly Robinson lives with her husband and their five children outside Boston.

Originally published in American Baby magazine, November 2005.

All content here, including advice from doctors and other health professionals, should be considered as opinion only. Always seek the direct advice of your own doctor in connection with any questions or issues you may have regarding your own health or the health of others.