Infant Communication: Learning in the Womb

Over the next few months we will introduce several posts about communication. Today’s post will focus on communication between caregiver and baby while baby is still in the womb.

Babies can hear and respond to sound prenatally and can even develop a preference to a particular sound, voice, or song after repeated exposure. Several studies have been conducted trying to explain how babies and caregivers begin their first communication. Although there is still a lot that is not known, and more research is needed, we’ve learned some interesting details that shed light on prenatal language acquisition.

·         Familiar rhymes are calming: One study measured changes in fetal heart rate in response to a rhyme that the mother recited during weeks 33-37 of pregnancy. When a recording of the rhyme was played at 37 weeks there was a noticeable decrease in the baby’s heart rate. There was no change in the baby’s heart rate when a different rhyme was introduced, indicating that a familiar rhyme was calming to the unborn baby.

·         Infants “recognized” stories heard in the womb: In a separate study, a 3-minute passage was read out loud twice per day for the last 6-weeks of pregnancy. After the babies were born the familiar passage and an unfamiliar passage were played for the baby. Infants preferred the recording of the story heard in the womb more frequently than the unfamiliar story. No preference was seen in a control group of infants not exposed to any story prenatally. From this study, authors concluded that babies do remember stories they heard while they were in the womb.

·         Listening to a familiar song changed babies’ states: A study of 2-4 day old babies monitored the infants as they listened to the theme song of a soap opera that their mothers reported watching prenatally. Compared to infants who were not exposed to the theme songs prenatally, infants who were exposed experienced a lower heart rate, a decrease in movements and transitioned to a more alert state while listening to the songs.

This information doesn’t tell us anything about the long-term effects of the sounds babies hear before they are born, but there is evidence that reading, singing, or playing music for your baby while you are pregnant can be calming both before and after birth.  Authors, however, warn against outside devises such as putting headphones close to the your pregnant belly, because it may effect  auditory development and interfere with behavioral state regulation.

Did you have an experience where your infant recognized a voice, song or story that they heard while you were pregnant? We’d love to hear your stories!

Reference: Moon CM, Fifer WP. Evidence of transnatal auditory learning. J Perinatol. 2000;S37-44.

Your Baby's Senses: The Magic of Touch

In prior posts in this series, we've talked about your baby's senses - taste, hearing, sight, and smell. Last but certainly not least, we'll turn to a sense that has a powerful influence on your baby's behavior, touch.

The sense of touch (the somaesthetic system) is the earliest to develop of all the sensory systems in the body. While the skin's sensitivity to touch, pressure, temperature, or pain is only part of the somaesthetic system, it is the part that most people think of when they hear the word "touch." From the first moments after birth, our instincts tell us to gently touch our babies, often starting with just a light stroke along their tiny arms or legs with our fingertips. We seem instinctively to understand that our touch plays a powerful role in our babies' lives. And so it does. The research into babies' somaesthetic system is filled with some older animal studies, dark circumstances in orphanages, and more recent and ongoing work. The findings are clear, a caregivers' touch is important for babies' growth and development.

Touch As A Basic Need
In the 1950s, a psychologist named Harry Harlow conducted a very dramatic (and likely unethical by today's standards) experiment with baby rhesus monkeys. He took the baby monkeys away from their mothers and put them into cages with 2 fake "mother monkeys" made of wire mesh, one bare and the other covered with terry cloth. The wire mother monkeys each had a bottle pushed through the wire so that the baby monkeys could feed. At the time, scientists thought that babies bonded with their mothers solely because mothers were a source of food. It was a surprise when all of the monkeys spent as little time near the bare wire monkey as possible and all their time clinging to the terry cloth covered mother monkey. Harlow revolutionized child care at the time, concluding that babies needed more than something to eat, they also need soft familiar touch. Tragically, human babies who have been removed from conditions of neglect (like in overcrowded and understaffed orphanages) struggle to function, socialize, and communicate. While the lack of touch is not the only reason for these children's problems, it is considered by developmental scientists and as a powerful contibutor.

Touch Plays a Role in Communication
Touch has been shown to be a way that caregivers and babies communicate. When mothers use touch as part of games that they play with their babies (like tickling their tummys or gently touching their noses), they are rewarded with bigger smiles and more playtime.Most parents understand that a light tickling touch or a firm stroke on baby's back communicate different messages. Using touch, parents can help babies stay alert and encourage their babies to explore their world. A restraining touch can also be used as a warning and to  prevent babies from hurting themselves.

Touch Can Help Calm Babies
When babies cry, adults instinctively want to hold and touch them gently. We somehow know that while we can reassure our babies with our words, touch plays a special role in helping babies feel safe and loved. Repetitive touch (like rubbing a baby's back) is a common part of parents' efforts to calm babies and babies who are touched spend less time being fussy. An interesting side effect - when parents calmly stroke their babies' backs, they tend to become more calm themselves.

The study of babies' sense of touch is relatively new. While the research into the need for touch goes back more than 50 years, today's researchers are learning the role that touch plays in the development of babies, physically, emotionally, and socially. Stay tuned and we'll talk more about touch in future posts.

References
1. Harlow HF. The nature of love. American Psychologist, 1958: 13: 673-685.
2. Provence S and Lipton RC. Infants in institutions. New York; International Universities Press, 1962.
3. Stack DM. Touch and physical contact during infancy: discovery the richness of the forgotten sense. In: Infant Development (2nd Ed), Wiley-Blackwell, 2010.

Your Baby’s Senses (Part 4): Sight

By Jennifer Goldbronn, MAS, RD

Today, we’ll continue our series on infants' senses by sharing information about the sense of sight. First, we’ll look at some of the milestones related to visual development in the first 6 months of life and then we’ll answer 2 common questions parents have about their babies’ sight.

The First 8 Weeks

A baby’s vision begins to develop at birth and is dependent on normal function of both the neurological system and structures of the eye. Newborns can see black, white, and shades of gray and can focus well to about 8-12 inches; they can see longer distances, but they can’t control the muscles in their eyes that allow them to see distant objects clearly. Because they can only focus a short distance, much of their vision is blurred. However, practice makes perfect; babies improve their focus by first focusing on faces and then moving on to bright objects nearby. At first, newborns can focus for only a few seconds at a time, but by 8 weeks, babies can focus their eyes on their parents’ faces for longer periods.  The ability to focus is not the only thing needed for babies to see clearly. They must also develop "visual acuity," or the ability to see details. While most structures of the eyes are completely developed at birth, the visual parts of the brain are not fully developed.  Studies show that during the first month of life babies’ visual acuity is about 20/120 (The Smith-Kettlewell Eye Research Institute). What exactly does that mean? If given an eye exam (and they could read), they would be able to read the big “E” at the top of the eye exam chart only. This is about 6 times worse than a normal adult seeing 20/20.

2-4 months

By 2-3 months, babies are able to follow people or objects with their eyes, and by 4-months, babies begin to learn hand-eye coordination as they begin to reach for objects. Their ability to see details (visual acuity) improves as well; by 4 months, babies’ vision has improved to 20/60. Then, as babies learn to roll over, sit up, and pull up, eye-body coordination begins. Eye-body coordination is simply learning to control body movements within the world around them.  Babies’ peripheral vision becomes almost as good as that of adults by about 4-months old. One study using flashing lights as part of a test of peripheral vision in infants found that newborns oriented towards the flashing lights out to 30 degrees in their field of vision. As babies got older, peripheral vision improved until infants at 4-months old could see almost as far as adults do.

4-6 months

 “Two-eyed” or “binocular” vision begins by 4-5 months so that babies fuse what they see from both their right and left eyes into one image, allowing them to develop strong depth perception. By 4-5 months, babies also begin to see in full color! Imagine how exciting their world becomes. All of these visual skills continue to improve over time, and by 6-months, many babies have developed 20/20 vision as they are able to see images more sharply and in greater detail.

2 Common Questions about Infant Vision

Should I worry if my newborn is cross-eyed?

No! Young babies must learn to use their eyes together. They begin to practice this skill by following objects with their eyes as they learn how to track and use their eyes together. This takes neuromuscular control that babies must learn over time. By about 4-5 months most babies have learned to coordinate their eyes together and the crossed eyes should stop. You shouldn’t worry about a young babies being cross-eyed unless his eyes cross after 5 months of age; then you should contact an ophthalmologist.

How important is it for my baby to have black and white toys?
Many toy stores sell black and white toys, claiming that these encourage visual development of infants. While it’s true that infants prefer to look at high contrast (like black and white) images because they are the most visible to them, high contrast patterns are not the only ones babies can see. Babies can actually tell the difference between much subtler shades of gray and their sensitivity to contrast becomes 10 times better than at birth by only 9-weeks, meaning it’s almost as good as that of adults. It’s important to give babies the opportunity to see other colors (besides black and white) and their subtleties and to let them explore important objects such as your face, your hand or their own hands and feet.

References and Resources

Lewis TL, Maurer D. Multiple sensitive periods in human visual development: evidence from visually deprived children. Dev Psychobiol. 2005; 46: 163–183.

Children’s Vision Information Network: http://www.childrensvision.com/development.htm

American Optometric Association: http://www.aoa.org/x9420.xml

What Can My Baby See? The Smith-Kettlewell Eye Research Institute: http://www.ski.org/Vision/babyvision.html

Your Baby's Senses: Smell

In previous posts, we've shared information about your baby's senses of hearing and taste. As we continue this series on baby's senses, we move on to babies' sense of smell.

Babies’ sense of smell, called “olfaction,” is highly developed at birth. Scientists think a baby’s ability to smell his mother is one of the important ways he learns to recognize her. Newborns spend a lot of time with their eyes closed! Researchers have found that newborns are able to tell the difference between the smell of their mothers and the smell of other women (yes, they really did a study!). Babies’ early exposure to a smell (in the first couple of hours after birth versus more than 12 hours after birth) results in a stronger and longer memory of the smell. This may be because newborn babies learn from their senses best when they have high levels of the hormone norepinephrine and this hormone is high in most babies in the first few hours after they are born.

Babies don’t have ability to know what smells are; they won’t know a flower or diaper by its smell – that takes experience. But, babies are calmed by familiar smells that they associate with good experiences (like a loving touch or breastfeeding). In contrast, babies may turn away from strangers with strong unfamiliar odors, so you might ask Aunt Mildred not to wear too much perfume when she comes to visit!

Because babies are more likely to remember the odors they were exposed to very early in life, they are more likely to be familiar with and calmed by the smell of their own mothers – since she’s right there after birth. These studies do not mean that babies won’t be able to recognize their mothers’ smell if they are not with her in the first hour or two, but it might take longer than those who are physically close to their moms earlier in life. Many studies have shown that babies who are breastfed or given their mothers’ breast milk during a painful procedure (like getting blood taken) are calmer than those who are not. Researchers think that the combination of the smell of their mothers and the sweet taste of the milk helps babies deal with the stress.

Skin-to-skin contact for about an hour immediately after birth increases babies’ recognition of the smell of their moms’ milk at 4 days postpartum. Early skin-to-skin contact has many benefits for mom and baby and many hospitals encourage the practice immediately after birth, during the best time for learning. Dads can make sure that baby is familiar with their smell by cuddling close early and often!

References

1. Winberg J, Porter R. Olfaction and human neonatal behavior: clinical implications. Acta Paediatr 1998; 87: 6-10.
2. Mizuno K et al. Mother-infant skin-to-skin contact after delivery results in early recognition of own mother’s milk odor. Acta Paediatr 2004; 93: 1640-5.
3. Romantshik O et al. Preliminary evidence of a sensitive period for olfactory learning by human newborns. 2007; 96: 372-376.
4. Nishitani S, Miyamura T, Tagawa M, Sumi M, Takase R, Doi H, Moriuchi H, Shinohara K. The calming effect of a maternal breast milk odor on the human newborn infant. Neurosci Res. 2009;63:66-71.
5. Shah PS, Aliwalas LI, Shah V. Breastfeeding or breast milk for procedural pain in neonates. Cochrane Database Syst Rev. 2006;3:CD004950.
6. Delaunay-El Allam M, Marlier L, Schaal B. Learning at the breast: preference formation for an artificial scent and its attraction against the odor of maternal milk. Infant Behav Dev. 2006;29(3):308-21.

Your Baby's Senses: Taste

By Jennifer Bañuelos, MAS

Last week, we started a series about sensory development with a post about hearing. Today, in the second part of the series, we will cover another of the 5 senses, taste!


Taste versus Flavor

In the medical dictionary, taste is defined as “the sense of perceiving different flavors in soluble substances that contact the tongue and trigger nerve impulses to special taste centers in the brain.” What does that mean to all of us non-doctors? It means that taste is basically a chemical reaction; when food (the soluble substance) hits our tongue, the chemicals in the food stimulate our taste buds, sending a message to our brain telling us if the food contains salty, sweet, sour, bitter, or umami compounds. Flavor, however, describes the perception about what is being consumed; it is the combination of 3 senses, what is tasted on the tongue, what is smelled with the nose, and the physical feeling of the food in the mouth (more on smell and touch in future posts). So, when we say something is “spicy” or “tastes like chicken” we are actually referring to flavor.

The Science of Taste

Although scientists have been studying taste for hundreds of years, they continue to discover new information. For example, it was originally believed that there were 4 basic tastes, sweet, salty, sour, and bitter, but over the last decade, scientists identified a 5th flavor, umami, described as a “pleasant savory taste.”(Umami Information Center) There is also new information about how the tongue and taste buds function and where they are located. Researchers have known that different areas of the tongue are more sensitive to specific flavors than others; the tip of the tongue is most sensitive to sweet, then along each side there are sensitive areas for salty, followed by sour, and bitter on the back of the tongue. The middle of the tongue was thought to be the least sensitive area. Recent research has indicated that our bodies may be much more complicated than described by this “tongue map.” There is now evidence that there may be taste receptors in other areas of the digestive tract, not just on the tongue! (Beauchamp 2011)

First Tastes

Babies’ first tastes occur long before birth. The amniotic fluid that surrounds a baby in the womb is affected by foods the mother consumes, so when the baby swallows this fluid, she is exposed to different flavors. In fact, studies have shown that babies may prefer flavors they were exposed to before they were born. (Beauchamp 2011) Maternal diet also affects the flavor of breast milk and studies indicate that babies who are breast fed may be more accepting of a variety of flavors once they start eating solid foods. (Beauchamp 2011; Maier 2008;)

Individual Taste

Some preferences are hard-wired into our brains. For example, babies are born with a preference for sweet and an aversion to bitter. (Beauchamp 2011; Schwartz 2009) Evolutionarily, this makes sense because foods that are sweet tend to by high in calories and bitter foods are often poisonous.

In a recently published study, researchers evaluated infant acceptance of the 5 tastes at 3, 6, and 12 months of age. By measuring both the volume consumed and facial expressions during consumption in the same infants at 3 different ages, they were able to present a more detailed picture of how taste preferences change with age compared to studies that only use 1 measurement. Much of what they found was consistent with previous findings; preference for sweet is present at birth and decreases with age, while acceptance of salty foods appears between 3 and 6 months of age. They also describe some novel findings. For example, for sour and bitter tastes, preference differed between the 2 methods of measurement; the consumption measurement indicated that the infants were indifferent to both tastes, but facial expressions expressed obvious rejection. They also found that as babies got older, they became more and more unique in terms of taste preference (once again, illustrating that all babies are different!). (Schwartz 2009)

Can you Teach Good Taste?

Although there is more to learn about exactly how our bodies sense tastes and flavors, using what is currently known, we have some suggestions to help parents promote a varied diet for their babies!

• Start when you are pregnant - Eating a varied diet while pregnant is good for you and will expose your unborn baby to all the flavors you love!

• Breastfeed – Continuing to provide a variety of flavors to your baby through your breast milk can increase acceptance of solid foods when your baby is old enough.

• Lead by example – If your baby sees you eating healthy foods, she’ll learn from you!

• Think outside the jar - Babies don’t need to be limited to rice cereal and applesauce. Although you should wait a few days before introducing a new food (to identify an allergy), babies can eat almost anything if it is prepared in accordance with their chewing and swallowing abilities.

• Be patient – Remember, babies’ preferences change over time. Also, studies have shown that it can take 10 to 15 times for a baby to learn to like a new food, don’t give up.

References:

Mosby's Medical Dictionary, 7th edition. Mosby Elsevier St. Louis, MO 2006

Umami Information Center, http://www.umamiinfo.com

Beauchamp G, Mennella J. Flavor Perception in Human Infants: Development and Functional Significance. Digestion (2011) 83(suppl 1):1-6.

Maier et al. Breastfeeding and experience with variety early in weaning increase infants’ acceptance of new foods for up to two months. Clinical Nutrition (2008) 27:849-857

Schwartz et al. Developmental changes in the acceptance of the five basic tastes in the first year of life. British Journal of Nutrition (2009) 102:1375-1385.

Your Baby’s Senses: Hearing

Imagine what it must have been like during those first moments when your baby came into the world blinking against the light, his muscles tensing as a flood of new sensations washed over him. Suddenly, he was hearing the sounds of excited voices, seeing the contours of your face, feeling your fingers stroke his back, smelling the air around him, and tasting your salty skin as he nuzzled in as close to you as he could. Because babies can’t use words to communicate with us, many parents wonder how well babies can use and learn from their senses. In this new series, we’ll share what we’ve learned about the amazing process of sensory development in babies. We’ll start with your baby’s sense of hearing.

The Sounds Inside

The physical structures needed for hearing (babies' ears and all the structures inside) develop entirely before babies are born. During the third trimester, the auditory nerve is developed well enough that the babies can hear (and remember) many of the sounds they hear daily from the world outside the womb. Researchers have shown that newborns are familiar with the voices of their mothers and fathers and that they are particularly interested in hearing human voices as compared to other sounds. Brain development involved in the discrimination and isolation of sounds continues well into the baby’s first year of life.

Newborn Hearing

By the time they are born, babies’ sense of hearing is one of their most developed sensory systems. While newborns can hear many of the sounds around them, they may not hear the quieter ambient sounds right after birth. If you speak to your newborn while he’s alert and not distracted, he will become more focused, quieter, and slow down his movements. He may attempt to turn toward the sound of your voice but some babies take a little time to do so easily. Babies do much better in responding to sounds when they are held in a relatively upright position and calm and alert. If you have any concerns about your baby's hearing, you should speak with your doctor.

Making Sounds “Fit” Babies' Needs

Mothers automatically use a higher pitched, lilting voice when speaking to their babies – this is called “Motherese” and we’ve talked about the importance of using this kind of communication in earlier posts. You’ll find that babies prefer “Motherese” when they are alert and lower softer tones when they are drowsy. Of course, dads can use their own type of "Fatherese." When dads raise the pitch of their voices and use longer tones as they speak, they will find that they can keep their infants’ attention a little longer. Researchers also have found that babies seem to prefer “happy voices” versus those that sound more neutral or negative. Both parents can match the tone and pace of their voices with babies’ readiness and interest by watching for cues. By 4 to 6 weeks of age, your baby will try to vocalize back to you, first making noises simultaneously as you speak and then by taking turns with you. By 5 months, babies have learned to identify the peculiarities of their own language and between 6 and 8 months they are able to tune out sounds that are not used in their own language. These early steps are important for babies' development of language.

Next time: More about your baby’s senses

References

1. Berger KS. The Developing Person. New York, Worth Publishers, 2003.
2. Nugent JK et. al. Understanding Newborn Behavior and Early Relationships. Baltimore, Paul H. Brookes Publishing, 2007.
3. Lester BM and Sparrow JD (Eds). Nurturing Children and Families. Malden, MA, Wiley-Blackwell, 2010.