THE EXPERIMENT
Place your baby on your lap and let him play with one or more rattles for several minutes each. Keep track of how many times he makes noises or babbling sounds that are coordinated with rhythmic movement (for instance, repeating a syllable each time he shakes a rattle). Then place him on the floor and spend some time reading books and playing with toys. Again, note the frequency of coordinated vocalizations and rhythmic movements.
THE HYPOTHESIS
Your baby will often make sounds to accompany his rhythmic movements, particularly when playing with the rattles. Vocal-motor coordination will be highest among older babies in the 6- to 9-month range, and there will be greater coordination with arm movements than with leg movements. In addition, rhythmic sounds (such as a repeated syllable) will be more likely to occur during rhythmic movement than without rhythmic movement.
THE RESEARCH
It’s well known that both adults and children coordinate gestures with speech when they communicate. In 1999, two developmental researchers proposed a model for how babies come to develop a coordinated gesture-speech system. They rejected the notion that gestures and speech are two independent communication processes and argued instead that they are two parts of a unified system of communication, in which each is closely linked with, and able to influence, the other. In a 2005 study, researchers examined motor-speech coordination in its early stages, at around the time babies begin to babble, to test the theory of a closely coupled gesture-speech system. They observed babies at home with their parents during structured playtime, which included a few minutes playing with rattles, followed by time spent reading books and playing with toys. They found that in each of the four age groups tested (6, 7, 8, and 9 months) the rate of vocal-motor coordination was greater with arm and hand movements than with other body movements, and rattle play produced the most frequent vocal-motor coordination, which increased from 6 months to 8 months and then slightly decreased at 9 months. Consistent with their hypothesis that the gesture-speech system is closely coupled, the vast majority of coordinated bursts of speech and movement were either movement-initiated (such as when a baby bangs his arm, then begins to vocalize) or synchronous (in which movement and vocalization begin at the same time). And when a gesture was made with only a single arm, it was usually with the right arm, consistent with adult gesturing.
The researchers in the 2005 study concluded that the results of their experiments support the earlier claim of a closely coupled motor and speech system. Based on their results, they proposed the following development scenario:
Babies begin to make rhythmic movements long before they begin to babble. By the time that babbling begins, the rhythmic movements are well practiced enough to “train” vocal activity, by giving it a rhythm of its own. This encourages what developmental researchers call reduplicated babble—the production of repeated syllables. Once babies begin to produce reduplicated babble, the coordination of rhythmic speech and movement becomes more frequent, which further strengthens the motor-speech link. By the time the child reaches between 9 and 12 months old (about the time that babies say their first word), the coordinated gestures are made mostly with the arms, while coordinated leg movements tend to fade out.
THE TAKEAWAY
So strongly linked are gestures and speech that it can seem that crippling one might cripple the other. In fact, you may have heard some frequent gesticulators remark that if you were to tie their hands behind their back, they wouldn’t be able to talk. As you observe your baby making coordinated, rhythmic movements and sounds, you are witnessing the formation of that bond between vocal and motor systems. You can promote this type of activity by allowing your baby to play with rattles and other noise-making toys, which they can shake to produce rhythmic sounds. Oh, sure, you might need to pop a couple Motrin afterward—but at least you’ll know you’re furthering your baby’s development.
25
Sizing Things Up
Age range: 6–9 months
Experiment complexity: Simple
Research area: Motor skills
THE EXPERIMENT
For this experiment, you’ll need two balls: a small one that your baby can easily grasp and hold with one hand and a larger one that your baby will need two hands to hold. Hold the small ball in front of your baby and note whether she reaches for it with one hand or both hands. Then hold the larger ball in front of her and again note whether she reaches for it with one or both hands. In each case, after she grasps the ball, let her hold and play with it for about 30 seconds. Repeat the presentations until you can determine a reaching preference: Does your baby prefer to reach consistently with a single hand or with both hands? If you are able to establish a reaching preference, you’ll then move to the next part of the experiment, during which you will present your baby with only the object whose size does not match her reaching preference. For babies who prefer to reach with two hands, repeatedly present the small ball and see whether she’ll switch to a one-handed reach. For babies who prefer to reach with one hand, repeatedly present the larger ball and see whether she’ll switch to a two-handed reach. Repeat these presentations about 10 times.
THE HYPOTHESIS
Despite repeated opportunities to grasp the small ball with one hand (or the larger ball with two hands), your baby will continue to use her preferred reaching style. The younger the baby, the more likely she will be to persist with her established reaching preference.
THE RESEARCH
A 2009 study presented 6-, 7-, 8-, and 9-month-old babies with small solid balls (about two inches in diameter) and larger solid balls (about five inches in diameter) to determine a reaching preference. The vast majority of the babies responded mainly with two-handed reaching. A few preferred one-handed reaching. And a small number showed no consistent preference, but instead varied their reaching style based on the size of the ball. Of those who showed a one-handed preference, the majority continued to reach with one hand when they were repeatedly presented with the larger ball, and of those who showed a two-handed preference, the majority continued to reach with two hands when they were repeatedly presented with the small ball.
The researchers found that unlike adults, who can immediately adapt their reaching style based on their prior experience holding an object, infants in the age groups tested in this study had a difficult time overcoming their innate reaching preference, even after repeated exposures to the object. This suggests that the process of determining a method of reaching for an object that is appropriate for the object’s size is a protracted developmental process.
THE TAKEAWAY
Sometimes, you’ll find yourself marveling at how quickly your baby is able to pick up a new task. Other times, it can take her months to master what may seem to you to be a relatively simple skill. You might not know why, but there’s usually a good reason. Sometimes, other aspects of their development take precedence; other times, a skill requires the convergence of several different developmental milestones before your baby can make solid progress. Whatever the reason, be patient—and be prepared to celebrate when your baby finally reaches the top of the hill!
26
Mirror, Mirror
Age range: 6–9 months
Experiment complexity: Simple
Research area: Cognitive development
THE EXPERIMENT
Place your baby on the floor or in a high chair in front of a large mirror. Allow her to spend time looking at the mirror, and carefully observe her behavior over a two-minute period, starting from when she first looks at the mirror. Is she interested in the image of herself? Does she point to, touch, or otherwise interact with the image? Is her mood happy and friendly, scared, shy, or irritated? Does she seem to recognize herself in the mirror? If she moves a body part, does she notice that the baby in the mirror also moves the same body part?
TWEAK IT
Invite a friend with a baby of the opposite sex to al
so conduct this experiment, and compare the results.
THE HYPOTHESIS
Even if your baby is as young as 6 months old, she will spend a significant amount of the two-minute period looking at the mirror. Older babies (around 8 or 9 months old) will be more likely to smile or laugh and to attempt to interact with the mirror by touching or licking it.
THE RESEARCH
In a 2007 study, researchers observed the behaviors of three groups of babies (6, 8, and 9 months old) who were given the opportunity to interact with a mirror. The infants in all three groups spent a considerable amount of time, ranging from 85 to 90 percent of the two-minute total, looking at the mirror. At 6 months, the babies were attentive but did not display many attempts at interaction. The older babies, on the other hand, showed signs of interaction. More than 40 percent of the 8-month-olds and more than half of the 9-month-olds displayed behaviors that the researchers described as happy or friendly, which included smiling or laughing, and attempts to touch, lick, or otherwise make contact with the mirror. One finding that surprised the researchers was that at 8 and 9 months, boys made about twice as many attempts at interactivity as girls did.
Previous studies involving infants and mirrors had demonstrated that as early as 3 months old, babies’ behaviors changed when looking at their reflections in a mirror. For instance, a 1972 study found that babies smiled and cooed at the image and reached out to touch it. However, other studies have concluded that the ability to recognize that the image in a mirror is a reflection of oneself does not emerge until after the first year, between 14 and 22 months old. For instance, in that same 1972 study, a test was devised in which a smudge of makeup was placed on babies’ noses. Around a year and a half old, babies reached for their own noses when they saw themselves in the mirror, an indication that they understood the reflection to be an image of themselves; younger babies, however, failed to show such a reaction.
The results of the 2007 study build on these results and demonstrate that by 6 to 9 months old, babies will interact with a mirror image in social ways, and they appear to show signs of recognizing that the movements of the baby in the mirror correspond to their own movements.
THE TAKEAWAY
Watching babies interact with their mirror images can be a lot of fun—and can also lead to a lot of smudges. You can take it a step further by spending time looking in the mirror together with your baby. For instance, you might look at her, then look to her reflection in the mirror, and see whether she looks at you or your reflection.
27
Capturing the Cup
Age range: 6–9 months
Experiment complexity: Moderate
Research area: Cognitive development
THE EXPERIMENT
For this experiment, you’ll need a medium-size cardboard box with one side open, and a large coffee cup with a handle. Seat your baby in front of a table. Place the box on the table at your baby’s eye level, with the open side of the box facing upward. Now, put the coffee cup inside the box and make sure that your baby cannot see what’s inside. Next, allow her to watch a friend slowly reach into the box from above. The friend’s grasp should be wide, as if he is intending to pick up the cup by its rim rather than by the handle. Then, move the box out of the way so that your baby can see that your friend has indeed grasped the cup’s rim, rather than the handle, and is holding the cup slightly above the table. Use a stopwatch to time how long your baby looks at the cup.
A few days later, repeat the experiment. Your friend’s grasp should still be wide as he lowers his hand into the box, but this time, he should grasp the cup by its handle. Again, time how long your baby looks at the cup.
THE HYPOTHESIS
Your baby will look at the cup longer the second time.
TWEAK IT
If a friend has a baby of about the same age, you can present one of the two conditions (holding by rim and holding by handle) to each baby and compare the results.
THE RESEARCH
In a 2009 study, 6- and 9-month-olds were shown a short video in which a hand reached into a box with either a wide or a narrow grasp. Then, they were shown two still images—one of the hand grasping the cup by the rim and one of the hand grasping the cup by the handle—and their looking times were recorded and analyzed. The analysis showed that the babies looked longer at the image in which the final grasp type (wide or narrow) did not match the anticipated grasp type. So, for instance, the babies who saw the hand begin with a wide grasp looked longer at the image in which the hand used a narrow grasp to hold the handle than the image in which the hand used a wide grasp to hold the cup by its rim. The researchers concluded that the babies were able to form expectations about the final grasp type based on the grasp type during the hand’s approach, and they were surprised when the final grasp type didn’t match, resulting in longer looking times.
The researchers concluded that babies as early as 6 months old are able to infer the size of an unseen target object based on the way a person reaches for it. This has implications for developmental researchers who study goal-oriented actions.
The researchers also noted that even though their study showed that 6-month-olds are able to infer the size of the target object based on the grasping style during the approach, an earlier study showed that infants don’t themselves begin to adjust the width of their grasp according to the size of the object until about 9 months. Thus the results lend some support to the idea that babies are able to understand and make inferences about an action even before they are able to perform the action themselves.
THE TAKEAWAY
You might think this little coffee cup exercise is no biggie, but all sorts of complicated processes are happening in your baby’s head as she observes it. Not only does she have to size up the grasp style and connect it with the size of an object, but she also has to grasp the goal-oriented nature of the action. As your baby grows, she’ll become even more adept at figuring out the goals of other people and anticipating their consequences. You can help her make those connections by pointing out the actions in a sequence and showing how one follows the other.
Tools of the Trade
A number of universities have baby labs devoted to conducting experiments on wee ones. For instance, Cornell operates the Behavioral Analysis of Beginning Years (B.A.B.Y.) Laboratory, which studies early communication, cognition, and language. Rutgers runs the Infancy Studies Laboratory, which is part of its Center for Molecular and Behavioral Neuroscience. Berkeley’s Early Learning Lab studies how babies and young children pick up language and learn about probability and how to categorize things. Stanford’s Center for Infant Studies focuses on vision and neurodevelopment, language, and social cognition. In the United Kingdom, Oxford’s Babylab studies elements of language acquisition and visual processing. At Yale’s Infant Cognition Center, researchers study how babies learn about their physical and social worlds. And UCLA’s Baby Lab focuses on perceptual and cognitive development.
Most baby labs recruit their young subjects through a mixture of targeted advertisements in local newspapers and parenting publications and direct solicitation based on a review of recent birth announcements and public records. Babies who participate in a research study are often given a small gift, such as a college T-shirt or a “young scientist” certificate.
28
Grabby Hands
Age range: 6–10 months
Experiment complexity: Simple
Research area: Motor skills
THE EXPERIMENT
You can conduct this experiment three times, when your baby is 6 months, 8 months, and 10 months old. Tie a toy to the end of a two-foot-long piece of string or attach it to the end of a rod of similar length. Place your baby into a seat and slowly spin the toy in a clockwise circular pattern at about the height of his nose. As he reaches for the toy, take note of whether he uses his left hand, his right hand, or both. If he successfully grasps t
he toy, let him play with it for a few seconds, and then repeat the experiment, but this time, spin the toy in a counterclockwise direction. You can repeat the experiment multiple times, alternating clockwise and counterclockwise spins.
THE HYPOTHESIS
At 6 months and 10 months, your baby will not show a significant handedness preference, but will likely reach for the toy with his left hand when the toy is moving from left to right and with his right hand when the toy is moving from right to left. At 8 months, however, your baby will likely reach with his right hand no matter which way the toy is traveling.
THE RESEARCH
Previous studies had established that infants much younger than those in the test range are able to make predictive reaching motions—that is, they reach out for a moving object in anticipation of its arrival in a certain location, rather than reaching for it in its current location. A 2009 study sought to investigate the methods that babies of different ages use to reach for moving objects. Three age groups were tested: 6-, 8-, and 10-month-olds. A toy suspended by a rod was rotated in front of the babies, and the experimenters tracked the infants’ reaching and grasping movements. When the toy rotated from right to left, babies in all three ages reached with their right hand more than half of the time; the 8-month-olds showed the strongest preference for their right hand, using it about 80 percent of the time. When the toy rotated from left to right, babies in the 6- and 10-month groups reached for the toy with their left hand more than twice as often as with their right hand. But the 8-month-olds reached for the toy with their right hand about twice as often as with their left hand.
Experimenting with Babies Page 6
