Infancy

Newborns come equipped with pre-wired motor programs that help them adapt to the requirements of existence as a baby. For example, each baby's life is saved multiple times by the gag reflex.

The gag reflex is a vomiting-like reaction (reverse peristalsis). It occurs automatically when a substance threatens to go down the wrong tube, into the windpipe instead of the stomach.

What are some reflexes of newborns?

The sucking reflex has obvious adaptive value for infants. The sucking reflex is complemented by the rooting reflex: an instinctive tendency to turn in the direction of a light touch on the cheek. This helps the baby find the nipple.

Babies have a strong grasp reflex set off by a touch on the palm. They instinctively cling to a parent's hair and clothes. The grasp reflex is strongest in the first weeks after birth.

Some babies (not all!) can be suspended upside down from a clothesline during this period. They can grasp the line with both hands and feet like a tiny tree sloth.

Some of the baby's reflexes foreshadow more advanced abilities to come later. Babies make simple stepping movements if held upright and allowed to touch the balls of their feet lightly to a horizontal surface.

After a month or two, babies develop a smile reflex that can sometimes be set off by stimuli as simple as two dots inside an oval, on a piece of paper. The smile reflex has obvious adaptive value. Infanticide was common in ancient societies during hard times, and the formation of an emotional bond with parents might prevent this.

Differences among Newborns

Differences among babies are apparent soon after birth. Nurses who work in the nurseries of hospitals have a sophisticated three-part classification for the temperament of babies: (1) difficult, (2) easy, or (3) in between.

What differences are apparent soon after birth?

Some babies are born difficult. They cry more easily and for a longer time, respond less to cuddling and soothing, and they appear startled or irritated at small noises.

Other babies are born easy. They are calm, unperturbed by noise, and they are easy to calm down when they cry. These different types of babies have an influence on parental attitudes.

One category of babies is particularly hard on parents. These are small for gestation age (S.G.A.) babies.

Gestation is the time spent in the womb. Small for gestation age (S.G.A) babies have a low birth weight even if they spend the full nine months in the womb. Often they are irritable and hard to comfort. They are "born difficult," so to speak.

What are S.G.A. babies and how can they cause trouble for parents?

S.G.A. babies sometimes fail to perform the mother-baby dance (below). Instead of looking happy when resting and responding to cuddles, they look worried when resting and become even more upset if they are picked up.

This can lead to discouraged parents and a breakdown of parent-baby attachment. Such babies often come around to more normal behavior, later. The problem for parents is enduring the early months without getting discouraged.

Communicating with Newborns

Possibly the earliest and most primitive channel of communication between mother and infant is odor. Babies only a month and a half old can distinguish the odor of their mothers from strangers.

No such effect was found for fathers. In follow-up research 16 of 20 mothers were able to distinguish the odor of clothing worn by their own children from that of other children. (McCarthy, 1986)

What studies showed odor familiarity between mothers and babies?

Normal babies communicate with their parents through body language at an early age. Researcher Daniel Stern, author of The First Relationship (1982), took high-speed movies of parents interacting with babies.

When films were slowed down and viewed frame by frame, Stern found that tiny movements of the baby and the parents were synchronized (occurring at the same time or right after each other).

For example, the mother would tilt her head; at that exact moment the baby would throw out an arm. Or the baby would smile and the mother would smile a few milliseconds later.

How do normal babies "communicate" with parents before they can talk?

Harvard pediatrician T. Barry Brazelton commented in an interview that mothers and babies who relate to each other in this manner are a joy to watch.

Every movement is geared to the other's. It's like the mating dance of swans. It's a distortion to say who is leading whom, both are so locked into their interaction. (Newman, 1977)

What special noises do adults use with babies?

People make certain sounds more often when playing with a baby. They speak in a high, melodic voice, sometimes called cooing, used only with babies (and recognized all around the world).

Everybody recognizes baby talk and students above the age of 5 or so resent having it used on them by teachers (too patronizing!). But it comes out involuntarily when we see babyish objects.

A few days after a lecture on developmental psychology in which I mentioned the baby-talk voice, I was in a large department store. I heard the distinctive, high-pitched, cooing manner of speech wafting over the aisles from twenty or thirty feet away. It was the sound of baby talk from a group of female voices.

Rounding a corner, I saw a group of teenage girls examining a display of teddy bears! Perfect, I thought.

Teddy bears are like a supernormal stimulus designed to elicit mothering or parenting emotions (presenting the classic feature set of babyishness: soft jaw, big eyes, big head, fuzzy...) The cute little toys were eliciting the cooing sounds typically aimed at babies.

What is some evidence that "clicking" sounds are special to babies?

Adults also make a "click" or go "tch tch" or make kissing noises to get a baby's attention. Normal adults make these high-pitched sounds without thinking about it, and they make them only when trying to communicate with a baby.

Researcher Elliott Blass found that newborn babies respond preferentially to these sounds. The click was very effective when used as a signal (conditional stimulus) in a classical conditioning procedure. Babies showed evidence of conditioning more quickly in response to mouth clicks than with other sounds.

Blass consulted with Arnold Gould, who was curator of mammals at the Smithsonian Institution. Gould told him that all mammals click to their young. "If you're a mammal, you click." (Kolata, 1987)

Some students express surprise at this. There are several reasons we might not be aware that we click to babies.

(1) It is automatic and apparently instinctive (appearing in all human cultures) so we don't say to ourselves, "I see a baby; I think I'll make high-pitching noises and clicks." Also (2) we don't see many references to the noises in print, because clicking is not easy to show with English letters. We might represent them with "Tch Tch" or by noting that a person is "making kissy noises."

Early Language Sensitivity

DeCasper and Fifer (1980) provided evidence that babies recognize their mothers' voices shortly after birth. Using a nonnutritive nipple attached to a sensing apparatus, DeCasper and Fifer showed that newborns would suck more to hear a tape of their mother's voice compared to a tape of a stranger's voice. Because they were newborns, they must have become familiar with the mother's voice while still in the womb.

How did DeCasper and Fifer show that newborns recognized their mothers' voice? What did DeCasper and Spence find out?

In a follow-up study, DeCasper and Spence had 16 pregnant mothers read a three minute long passage from the Dr. Seuss book The Cat in the Hat to their fetuses twice a day for the last 6.5 weeks of pregnancy. The mothers were also recorded reading three minute excerpts from two other stories.

By the time the babies were born, the researchers calculated, they had heard The Cat in the Hat for about 5 hours. DeCasper and Spence used their sucking test again. The babies sucked more to hear The Cat in the Hat, regardless of whether it was in their mother's voice or another woman's voice, if that was the story they heard in the womb. (Kolata, 1984)

How did people respond to the news that babies could "learn in the womb"?

In what seems a parody of America's get-ahead culture, this research inspired educational courses for unborn babies. A California obstetrician named Rene Van de Carr founded a "Prenatal University" with a curriculum that started four months before birth. Parents used special phonelike devices strapped to the mother, to play the unborn baby sounds such as the alphabet or classical music.

There is no evidence that specially arranged stimulation helps babies more than natural stimulation. However, there is some research evidence (from Gordon Shaw and colleagues at the University of California) suggesting exposure to complex, classical music might stimulate brain development in children.

In response to this finding, Governor Zell Miller of Georgia arranged for Sony Corporation to donate tapes of classical music to mothers of newborns throughout the state in 1998, along with a brochure advertising its benefits.

Why did Governor Zell Miller of Georgia provide mothers of newborns with music tapes?

The program was already gone by 1999, so apparently only certain people from Georgia entering college around 2016 had this advantage. In reality, such a small amount of exposure so early in life is unlikely to have any lasting effect, and some researchers refer to the whole idea as a myth (Swaminathan, 2007).

The most robust finding from the hundreds of experiments on sound in the womb is that babies do learn the sound of their mother's voice in the womb. In experiments with newborns, even a brief stimulus (the word "baby") is enough to elicit an ERP (evoked response potential) different from normal, if the word is pronounced in the mother's voice. This change in brain waves occurs even if the baby shows no behavioral reaction on a non-nutritive nipple (Moon, Zemzach, and Kuhl, 2015).

The Importance of Touch

Babies inside their mothers experience lots of touch stimulation due to pressure and movement. Premature babies lying in a hospital crib do not receive nearly as much touch stimulation.

To see whether additional stimulation might help premature babies, Rice (1975) randomly assigned a group of 30 prematurely born infants into experimental and control groups. The experimental group was stroked and massaged over the whole body for 15 minutes, four times a day. Babies in the control group received normal hospital care without a daily massage.

What research did Rice carry out with premature babies?

At the age of four months, the babies in the experimental group were more advanced in their development. They had better motor reflexes and were "more socially adaptive and aggressive," responding more to their caretakers. Rice also noted that the babies seemed to enjoy the experimental treatment.

Infants quieted, smiled, established eye contact and vocalized. Mothers observed this behavior with interest and pleasure, relating their belief that the "baby likes being stroked and held by me." (Rice, 1975)

How did later research by Field support Rice's finding?

By the late 1980s many researchers agreed that touch played a critical role in development. Researcher Tiffany Field found that massaged infants gained weight 47% faster than non-massaged infants.

This weight gain occurred even though the two groups ate the same amount. Massaged infants typically left the hospital six days earlier, saving an average of $3,000 in hospital costs (Trotter, 1987).

How does touch have its effect, and how did research on rat pups demonstrate this?

Why does touch have this effect? Apparently touch stimulates brain chemicals that are crucial for growth.

Researcher Saul Schanberg and associates at Duke University demonstrated this with rat pups (newborn rats). A chemical called ODC (ornithine decarboxylase) disappeared from the rat pups' brains within 30 minutes after the rat babies were separated from their mother, and the rat pups stopped growing.

ODC is an enzyme that stimulates production of several other crucial brain chemicals. Normally mother rats lick their young, which stimulates the release of growth hormones. Schanberg demonstrated the same effect in laboratory experiments.

Schanberg said, "I couldn't get the lab technicians to actually lick the pups" But Gary Evoniuk, also of Duke, observed that stroking them heavily with a wet paintbrush had the same effect. Rat pups receiving daily wet paintbrush stimulation gained weight faster than other pups, although receiving the same number of calories in their food (Barnes, 1988).

Stress releases the pain-killing drugs called endorphins from the human nervous system. Endorphins inhibit the production of ornithine decarboxylase (ODC), the brain hormone that stimulates growth.

What seems to be the reason stress in mothers lowers the birth weight of babies?

These findings may also explain why mothers under a lot of stress during pregnancy often have underweight babies. The Duke researchers found they could duplicate the growth-stunting effects of separating rat pups from their mothers by injecting rat pups with endorphins.

Infant Information Processing

All sorts of surprising capabilities have been documented in young babies. We already discussed several: imitating faces and recognizing the mother's voice. Here are some others:

What are some other capabilities discovered in newborns?

Pointing. Thomas Hannan, a researcher at Duke University, produced video evidence that babies 3-8 weeks of age could point with their fingers. This was true even though the parents had not noticed it and did not believe the babies were old enough to point.

The behavior is identical to the pointing behavior of 1 year olds, Hannan said. By the time a baby is 1 year old, pointing is expected so parents recognize it (Turkington, 1992).

Number sense. Most infants can tell the difference between displays containing 8 and 16 dots, but not between 8 and 12 dots (Xu and Spelke, 2000). Researchers refer to an "approximate number system" (ANS) which is nonverbal and present throughout the lifetime.

The ANS is different from the exact number system that humans learn about in school. However, early development of the approximate number system (ANS) may predict later competency with the exact number system.

What is the approximate number system?

Some infants did better than others at 6 months on a "numerical change detection" study (discriminating between 10 and 20 dots). They had better skills with exact numbers when tested 3 years later (Feigenson, Libertus, and Halberda, 2013).

Language rule learning. Babies attend longer to sentences with unfamiliar structures than to sentences with familiar structures. This suggests that they are sensitive to the rules of language formation, well before they can talk (Marcus, Vijayan, Rao, and Vishton, 1999).

How is habituation used in many of these studies?

Many of these studies use a dishabituation paradigm (also called release from habituation). Habituation is the nervous system's tendency to respond less and less to a familiar pattern.

Babies habituate to familiar visual patterns and eventually stop looking at them. They perk up again and spend more time looking if they see a novel pattern (a change from the pattern to which they habituated).

To demonstrate a baby's approximate number system, the baby might be presented with a series of pictures showing ten objects, always in random positions with a variety of colors. Eventually the baby grows tired and starts to look away.

At some point, a picture with five objects is introduced into the series. If the baby suddenly orients to the stimulus and spends longer looking at the new picture than the preceding series, this is evidence that the baby notices a difference between ten and five items.

The findings above might be less surprising when one realizes similar capabilities have been demonstrated in non-human animals. Everything on the list above is a form of implicit or unspoken cognitive ability, very different from the skills cultivated in school, where conscious effort is required.

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References:

Barnes, D. M. (1988). Meeting on the mind. Science, 239, 142-144.

DeCasper, A. J. & Fifer, W. P. (1980). Of human bonding: Newborns prefer their mothers' voices. Science, 210, 1174-1176.

DeCasper, A. J. & Spence, M. J. (1986) Prenatal material speech influences newborns' perception of speech sounds. Infant Behavior and Development, 9, 133-150.

Feigenson, L., Libertus, M. E., & Halberda, J. (2013) Links Between the Intuitive Sense of Number and Formal Mathematics Ability. Child Development Perspectives, 7, 74-79. doi: 10.1111/cdep.12019.

Kolata, G. (1987). What babies know, and noises parents make. Science, 237, 726.

Marcus, G. F., Vijayan, S., Bandi, R. S. & Vishton, P. M. (1999) Rule learning by seven-month-old infants. Science, 283, 77-80.

McCarthy, P. (1986, July). Scent: The Tie That Binds? Psychology Today, pp.6-10.

Moon, C., Zernzach, R. B., & Kuhl, P. K. (2015) Mothers say 'baby' and their newborns do not chose to listen: a behavioral preference study to compare with ERP results. Frontiers in Human Neuroscience, 9, 153. doi:10.3389/fnhum.2015.00153.

Newman, D. J. (1977, June 15). Listening to Baby's Body Talk. Detroit Free Press, pp.1C,6C.

Rice, R. D. (1975, November). Premature infants respond to sensory stimulation. APA Monitor.

Rice, R. D. (1977) Neurophysiological development in premature infants following stimulation. Developmental Psychology, 13, 69-76. https://dx.doi.org/10.1037/0012-1649.13.1.69

Swaminathan, N. (2007, September 13) Fact or fiction? Babies exposed to classical music end uip smarter. Scientific American: The Sciences [blog] Retrieved from: https://www.scientificamerican.com/article/fact-or-fiction-babies-ex/

Trotter, R. J. (1987, May). You've come a long way, baby. Psychology Today, p.34.

Turkington, T. (1992, February). Infants do it–but what is the point? APA Monitor, p.18.

Stern, D. (1977) The First Relationship. Cambridge, MA: Harvard University Press.

Xu, F. & Spelke, E. S. (2000) Large number discrimination in 6-month old infants. Cognition, 74, B1-B11.

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