The First Signs of Intelligent Life

In the first few months, a baby's dominant, most fully evolved senses — touch, smell, and taste — are those that we grown-ups may take most for granted. In your little scientist's personal laboratory, the mouth and nose are as essential as the eyes and ears for gaining information.

Touch
Every object that enters an infant's hand — rattle, keychain, pebble, stray grocery receipt — goes express to the mouth. But these early oral encounters are not just about taste. For a newborn, the tongue and gums are vital organs for feeling out surroundings. A baby's sense of touch develops over several years from head to foot; even by age 5 the face and mouth remain more sensitive than the hands.

Smell and Taste
Closely related, these two "chemical" senses are almost fully mature at birth. In fact, by about your 28th week of pregnancy, your baby could smell almost everything you ate or inhaled.

It's believed that a newborn can recognize Mom by scent: At 10 days old, babies who are placed between breast pads from their mothers and those from other women turn toward the one bearing the odors of Mom's skin and milk.

Your baby's taste buds have been forming since eight weeks after conception. At birth, he can discern sweet, bitter, and sour flavors but not yet the taste of salt. He can even "rank" his preference for different varieties of sugar, from the sweetest on down. That's right: The craving that ultimately draws us toward the freezer department of the supermarket begins at birth — and for several sound reasons related to survival.

Sweet receptors in the mouth are linked with brain areas that release homegrown opiates, inducing pleasure, relieving stress, even blocking pain. "In nature," says Lise Eliot, Ph.D., author of What's Going On in There? How the Brain and Mind Develop in the First Five Years of Life, "sweet foods are the best sources of energy — and the safest to consume. And sugar definitely has a calming effect on babies."

Vision
Many people think a newborn's eyesight is blurry, but she simply has a very narrow range where focus is best: between 10 and 12 inches away, says Meltzoff. It's no coincidence that this happens to be the distance between an infant's face and that of a parent or other caregiver cradling her, whether to nurse or simply to commune.

It's well known that infants are drawn to high-contrast objects — those black-and-white mobiles arose from the discovery that because cones in the eyes (which process color) mature far more slowly than rods (which discern shades of gray), babies don't perceive much color until they're 2 to 4 months old. Bold stripes, checkerboards, and graphic shapes are all visually compelling to babies. But overwhelmingly, their favorite thing to look at, from birth, is a live human face (by the end of the first week, Mom's above all others).

Because an infant's central field of vision isn't much better than her peripheral vision (adults, by contrast, tend to focus on the middle of things), she may learn to identify some faces as much by their outer features — hairline, jaw, ears — as by their eyes, mouth, and nose.

Vision is the only sense that's not stimulated in utero, but it matures so dramatically from birth that acuity improves twentyfold within the first six months or so: from 20/600 to about 20/30 (20/20 is normal adult acuity). Those high-contrast mobiles and flash cards, by the way, will do nothing to improve your child's vision or IQ, say experts. A baby's normal environment provides plenty of contrast and other visual amusement.

Hearing
A baby is born able to recognize Mom's voice (he'll learn Dad's and siblings' within days) as well as any songs and stories she sang or read repeatedly during her third trimester. He'll even show a preference for the rhythms and sounds of the native language that was spoken when he was in the womb.

Yet while hearing is more mature than vision at birth, it's the tortoise of the senses, still fine-tuning itself when school rolls around. What neonatal ears don't do well is identify where in space a sound is coming from or separate the different components of complex "fast" sound, such as normal adult language. Recognizing a melody is far easier for an infant than recognizing a series of words. "Say the word 'cat' and you are making three different speech utterances in one sound, as compared to a single note of music," Eliot explains.

Music can greatly enhance a newborn's environment, but there are a couple of caveats: Babies prefer melodies with regular rhythms to atonal, syncopated, or otherwise irregular music. And infants don't yet have the skill that adults demonstrate so well at cocktail parties: the ability to screen out background noise and focus on a chosen sound. "Listening just to music, dancing with your baby, and singing to soothe him are all good activities. But at other times, especially when you're interacting, keep background music and other noise to a minimum," says Eliot. One of your baby's main jobs, from day one, is to learn language through face-to-face interaction, and he can't do it if the stereo, radio, or TV is constantly on.

Vestibular System
A sixth sense is also up and running; in fact, it's more active in a newborn than it will ever be again. The vestibular system governs our sense of balance and position in space. It's what ultimately allows us to do such simple things as turn our head while keeping our eyes fixed on a single point in space, or jog without seeing the world bob up and down before us.

A baby's vestibular system is actually overresponsive, perhaps because its stimulation is crucial to developing posture and motor skills. Within days of birth an agitated infant will be soothed more readily by gentle swaying, bouncing, and jiggling than by caretaker contact alone. And there's evidence that (within reason) the more vestibular stimulation babies receive, the more quickly their physical abilities develop.

Parenting Magazine, September, 2001