Don’t Try This at Home
Several of the projects in this book describe how to experiment with primitive reflexes in your baby. One infant reflex you should not try to elicit is the Moro reflex, which is also called the falling reflex.
This reflex, first described by pediatrician Ernst Moro more than 100 years ago, occurs when an infant feels as if he is falling. The baby throws his arms out until the falling sensation ends and then draws them back in again. Some developmental researchers have posited that there’s a good evolutionary basis for the reflex: If a caregiver accidentally loses her grip on the baby and the baby begins to fall, it is easier to catch him with his arms extended, increasing the baby’s chance of survival.
The Moro reflex is apparent from birth and usually subsides within three or four months.
Normally, the sensation of falling that causes the Moro reflex is quite upsetting for the baby and crying is common afterward; consequently, don’t try this on your own baby. (Your doctor may test for the reflex during a newborn evaluation, but unless you’re a doctor doing a clinical assessment, there’s no reason to put your kid through the distress.)
9
This Little Piggy Was Named Babinski
Age range: 0–24 months
Experiment complexity: Simple
Research area: Primitive reflexes
THE EXPERIMENT
Stroke the bottom of your baby’s foot, from her heel to the base of her toes.
THE HYPOTHESIS
Your baby’s big toe will bend up and back, and the other toes will fan out.
THE RESEARCH
In 1896, Joseph Babinski, a French neuroscientist, noticed that in healthy adults, stroking the sole of the foot makes the big toe curl downward—but in infants and in people with certain neurological conditions and spinal cord injuries, the big toe curls upward.
In infants, the Babinski sign, also called the plantar reflex, occurs because their nervous system is not fully developed. By around age 2, the Babinski sign is replaced by the reflex seen in healthy adults. If it does not go away or if it reappears later in life, it may indicate a neurological problem.
THE TAKEAWAY
Think of the Babinski sign as a tickle with a purpose. It’s a simple, noninvasive test that helps doctors assess the health of the nervous system. From a parent’s perspective, it’s a reminder that aside from the developmental changes that are easy to observe, such as physical growth, improved coordination, and the beginnings of language acquisition, there are other, more subtle changes taking place as your baby grows and develops.
10
A Memorable Smile
Age range: 2–4 months
Experiment complexity: Moderate
Research area: Emotional development
THE EXPERIMENT
Show your baby a photograph of an unfamiliar adult who is smiling and looking toward the camera. Let her gaze at the photo for about 20 seconds. Then show her two more photos. First, show her a new photo of the person with whom she was familiarized, but in this photo, the person should have a neutral (nonsmiling) expression. Next, show her a photo of a second unfamiliar person, also with a neutral expression. Take note of which picture she looks at more. A few days later, repeat the experiment using photos of two more unfamiliar adults—but this time, neither of the adults should be smiling in any of the photos.
TWEAK IT
If you have two babies of about the same age, you can test one with the smiling face and one with the neutral face, rather than testing both conditions on the same child. This more closely resembles the original experiment and reduces the chance that your baby’s familiarity with the test procedure will skew the results the second time around.
THE HYPOTHESIS
In the first part of the experiment, your baby will spend considerably more time looking at the unfamiliar face. But in the second part of the experiment, she may spend slightly more time looking at the familiar face.
THE RESEARCH
A 2011 study involving 3-month-old infants found that babies who were familiarized with a photograph of a smiling subject looked significantly longer at the photo of the unfamiliar person than at the photo of the original subject, no matter the order in which they were shown. But with the babies who were familiarized to a subject with a neutral expression, they actually looked slightly longer at the photo of the familiar subject if it was shown to them first.
The researchers theorize that the babies who were familiarized to the smiling face were better able to recognize the face later, and because babies would be expected to prefer novelty over familiar things in a case like this, they weren’t as interested in the familiar face—which would explain why they looked longer at the new face. The babies who were familiarized to the person with the neutral expression seemed to need a little extra time to recognize it later, based on their roughly equivalent looking times at the novel and familiar faces. The results of this study, the researchers say, cast into doubt the idea that facial recognition and emotional expression recognition are independent processes; rather, certain expressions appear to facilitate facial recognition. The results of this experiment are also consistent with similar experiments on adults.
THE TAKEAWAY
Just look at that adorable little face. You almost can’t help but smile at it. But if you still need prodding, now you have a firm scientific reason for doing so: It will help her learn to recognize you. One practical way to make use of this nugget of child-development knowledge is to create a photo flip book of family and close friends whom you want your baby to learn to recognize. Select pictures in which the subjects are giving big smiles. Their cheery expressions will heighten your baby’s ability to recognize them later.
11
Out on a Limb
Age range: 2–4 months
Experiment complexity: Moderate
Research area: Motor skills
THE EXPERIMENT
Lay your baby in a crib. Loosely tie a length of soft ribbon to each of her wrists. Attach the other end of one piece of ribbon to a mobile or other toy above the crib, such that if your baby moves the corresponding arm, the mobile will move. Attach the other end of the other piece of ribbon to some other fixed point near the crib, making sure that this string, when tugged, will not cause any sort of motion or noise.
THE HYPOTHESIS
Your baby will soon make the connection that her movements can activate the mobile. However, depending on her age, the specificity of her movements will vary. At 2 months old, she is likely to move all four limbs in an attempt to activate the mobile. By 3 months, she is likely to move her arms more than her legs. And by 4 months, she is likely to move the arm attached by ribbon to the mobile more than the other three limbs.
THE RESEARCH
As far back as the 1930s, researchers have been devising and documenting studies in which babies learn to connect a spontaneous action with a corresponding outcome. In 2006, researchers set out to examine how this skill develops over time. In their study, which involved 2-, 3-, and 4-month-old infants, the babies first spent a little bit of time in a crib with strings attached to their wrists, but with the strings unattached to the mobile. This allowed the researchers to establish a baseline for the frequency of their arm and leg movements. Then, they attached one string to the mobile and gave the babies six minutes to realize that their arm movements caused the mobile to spin. Next, they detached the string and recorded the babies’ limb movements for two minutes. As expected, the babies demonstrated more frequent limb movement than in the baseline period—they had learned that their movement caused the mobile to spin and were attempting (albeit fruitlessly) to make it spin again. With age, they became more specific about their movements. The 2-month-olds moved all four limbs at roughly the same frequency; the 3-month-olds moved their arms more than their legs; and the 4-month-olds moved the arm that had been attached to the mobile most
of all.
The researchers then tried to test whether the infants were able to retain a memory of the causal connection even after an intervening period. Sure enough, they found that after a five-minute play break, babies in all three age groups continued to move their limbs at a rate higher than the baseline period.
The results of this study add to an area of motor-development research that attempts to explain how a baby with a large freedom of motion (that is, the ability to move various limbs in various directions) learns to constrain those motions to accomplish a given task.
THE TAKEAWAY
Your baby is in the first stages of recognizing the connection between cause and effect. As she grows, she’ll develop a more sophisticated understanding of causality. First, she’ll learn that whacking things often generates noise or motion. Then, at some point, she’ll discover gravity, and she’ll delight in testing it by immediately dropping anything you hand her. It’ll take her much longer to pick up on more complex instances of cause and effect, such as those involving delayed effects. She’ll primarily learn these lessons through repetition, so have patience as she knocks her sippy cup on the floor for the umpteenth time.
12
Grasping Prep
Age range: 2–6 months
Experiment complexity: Moderate
Research area: Motor skills
THE EXPERIMENT
You’ll perform this experiment multiple times, starting from when your baby is about 2 months old, and up until she begins to successfully reach for and grasp a toy. When she is awake and alert, but not fussy or crying, place her in a reclined seat but don’t restrain her ability to move her arms. Sit facing her and talk to her to capture her attention as you introduce a small toy. The toy need not be unfamiliar to her, just as long as it captures her attention. Hold it in front of her, about an arm’s length away. Spend about 30 seconds observing her arm and hand movements, paying attention to their speed and frequency as well as the distance and smoothness of the movements.
THE HYPOTHESIS
Your baby will go through several phases in the weeks leading up to successfully reaching for and grasping a toy. In the early phase (8 to 10 weeks before successful grasping), the speed and length of arm movements will decrease. In the middle phase (4 to 6 weeks before successful grasping), the speed, number, and smoothness of arm movements will increase, and babies will move their hands closer to the toy than in the early phase. During the late phase (within 2 weeks of successful grasping), the speed, number, length, and smoothness of arm movements will be similar to that of the middle phase, but you’ll notice fine-tuning of the direction of arm movement and an increasing preference for upward rather than downward movements.
THE RESEARCH
A 2006 study tracked babies weekly, starting when they were about 8 weeks old, and continuing until they were able to successfully grasp a toy (around 20 weeks, on average). Each week, the babies were either presented with a toy or tested under similar conditions but with no toy. This allowed the researchers to determine whether the babies’ movements changed in the presence of a toy. Three-dimensional motion-capture technology was used to record the babies during the sessions, and the researchers’ findings were based on an analysis of that data.
The analysis found that some differences between the toy and no-toy conditions were specific to a particular phase, but across all three phases, babies showed a continuous decrease in the distance between their hands and the toy.
The results of this study demonstrate that when babies are presented with a desirable object, such as a toy, they begin to alter their arm movements well in advance of being developmentally ready to actually reach for and grasp the object. By determining which aspects of arm and hand movement are specific to one phase and which are continuous, the researchers can construct further hypotheses about the developmental factors that produce these behaviors.
The researchers say the results of this study establish normative developmental behavior—that is, behavior typical of children who do not have developmental delays. The data can now be used to identify atypical movement patterns in children who are at risk of developmental delays, such as babies born preterm. For instance, they suggest that preemies should be expected to have a longer middle phase than babies born full-term, as a result of possibly impaired muscle tone and other factors.
THE TAKEAWAY
Potentially months before your little one can actually grasp a toy that you hold out in front of her, she’s already got her eyes on the prize, and her body is responding to the presence of the toy in various ways. By charting her progress toward the goal, you can see how different factors that affect her performance, such as muscle control and visual-spatial coordination, come into play. And now that you know that your 2-month-old really wants that toy you’re dangling in front of her, even though she can’t reach it, be kind and place it in her hands at the conclusion of the experiment.
Don’t Try This at Home
In 1939, Mary Tudor, a speech-pathology graduate student at the University of Iowa, conducted an experiment on a group of orphan children in an attempt to determine what factors influence stuttering behavior. Half of the orphans she selected for the study stuttered and half did not. She divided the children into two groups, with each group containing both stuttering and nonstuttering children. Over a period of several months, she met with children in the first group, and whether they stuttered or not, she praised their speech and told them it was fine. Over the same period, she met with children in the second group, and whether they stuttered or not, she told them their speech was not normal and was in need of immediate correction.
At the end of the study—big surprise!—the children who were told their speech was not normal had become withdrawn and less likely to speak at all and their schoolwork suffered. The results of Tudor’s dissertation were never published in any academic journal, but the study was brought to light in a 2001 article in the San Jose Mercury News, in which several of the study’s subjects were interviewed. That article sparked a lawsuit that eventually ended in the state of Iowa agreeing to a substantial settlement—close to $1 million—to be dispersed to several of the surviving orphans, who testified that they had sustained lifelong harm as a result of the “Monster Study.”
Needless to say, experiments involving minors fall under greater scrutiny these days, and universities and other research institutions go to great lengths to ensure that children who participate in such experiments walk (or crawl) away from them just as happy and healthy as they came in.
13
Tongue Testing
Age range: 2–6 months
Experiment complexity: Simple
Research area: Social development and motor skills
THE EXPERIMENT
Place your awake, alert baby in a car seat in a room free of distractions. Stand in front of her so that your face is about a foot and a half away from hers. Look at her for 60 seconds with a neutral expression and don’t respond to her attempts to communicate. Count how many times she sticks her tongue out and how many times she attempts to reach toward your face. Then repeat the experiment, but substitute a doll’s face for your own and again count how many times she sticks her tongue out and how many times she attempts to reach toward the doll’s face.
THE HYPOTHESIS
Your baby will stick her tongue out most frequently at 2 months old and least frequently at 6 months old. For reaching, the trend will be the opposite: She will reach least frequently at 2 months old and most frequently at 6 months old.
THE RESEARCH
A 2006 study involving 2-, 4-, and 6-month-olds sought to identify how a baby’s oral exploration changes over time. The researchers found that when presented with a neutral-expression face, 2-month-olds stuck their tongues out an average of 4.6 times in 60 seconds, nearly double the average rate of 4-month-olds and almost 10 times the average rate of 6-month-olds. In contrast,
none of the 2-month-olds reached, and the rate at which 6-month-olds reached was several times higher than the 4-month-olds’ rate.
The study also found differences in behavior depending on whether the babies were looking at a human face or an object with human facial features (a mannequin). Babies in all age groups were more likely to stick their tongue out when looking at a human than a mannequin, and babies in all but the oldest group were more likely to reach when looking at a mannequin than a human.
So, at 2 months old, a baby’s tongue serves a function that is similar to the function her hands serve in the coming months: It’s a tool that allows her to explore interesting objects (in the case of the doll or mannequin) and react to unusual social situations (such as a face that gazes at her but doesn’t initiate or respond to communication). By about 4 months, the hands are starting to take the place of the tongue, and by 6 months, she will rely much more heavily on reaching.
THE TAKEAWAY
As adults, we don’t think of our tongues as a particularly effective (or hygienic) way to get to know the world around us, but when you’re an infant and haven’t yet gained full control of your limbs, the simple act of sticking out your tongue is about all you’ve got, so you make do. Because the tongue is so important as a sensory tool to young babies, resist the urge—within reason, of course—to keep your baby from slobbering all over stuff. Hand her a soft, washable book or a plastic teething toy and let her go to town. She’s not just salivating; she’s learning.
Experimenting with Babies Page 3