Experimenting with Babies
Page 9
Now you’ll repeat the presentation with the other two objects, but this time, instead of a neutral facial expression and neutral voice, you should use a fearful facial expression and negative tone of voice (begin with a gasp and continue with tense, rapidly spoken words). Even though your facial and vocal cues will be negative, during your description of the object, avoid negatively charged words such as ugly or scary. Instead, use factual, descriptive words. Then move both objects within your baby’s reach and give her about 30 seconds to play with them. Note which object she is more interested in.
THE HYPOTHESIS
Ten-month-olds will not show a preference for either object in either of the presentations. Twelve-month-olds, however, will gravitate toward the described object after the neutral presentation, but will avoid the described object after the negative presentation.
THE RESEARCH
In a 2003 study, 10- and 12-month-old babies watched video presentations in which an actress directed her attention to one of two objects in front of her and referred to the object using a neutral tone and expression. The babies were then able to play with the objects. Then half the babies were shown a similar presentation, but in this one, the actress took on a negative (fearful) tone and expression. The other half saw a presentation in which the actress took on a positive (enthusiastic) tone and expression. They were then permitted to play with the new set of objects.
The researchers found that the 10-month-olds didn’t show any significant difference in their response to any of the three conditions (neutral, negative, and positive). But the 12-month-olds were more likely to reach for the target object than the other object after the neutral and positive presentations and less likely to reach for the target object after the negative presentation. They were also more likely to adopt a negative state themselves.
The researchers concluded that the 12-month-olds were able to take cues from the actress’s expression and tone of voice and apply those cues to the specific object she was talking about, while the 10-month-olds had not yet acquired that ability.
THE TAKEAWAY
Being able to pick up on other people’s emotional cues is a fantastically useful skill. It can prevent you from unintentionally starting a bar fight. It can help you understand that if you walk into your boss’s office and find him weeping uncontrollably, you probably shouldn’t ask him for a raise at that very moment. It can also keep you out of danger, and that’s especially important for vulnerable little babies. By picking up on a fearful emotional state, they’re learning to avoid an object that could potentially harm them. This is about the time in their development, then, when you can point to dangerous things—the stovetop, the knife drawer, anybody with a face tattoo—and warn them to stay away.
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Walking Tour
Age range: 10–16 months
Experiment complexity: Moderate
Research area: Motor skills
THE EXPERIMENT
Conduct this experiment once your baby is walking independently. During a warm day, place a sheet of butcher paper about 12 feet long on a level outdoor surface and apply nonpermanent ink to her feet so that the toes and the heel of each foot are clearly marked. (If you’d rather do this experiment indoors, dip her feet in water instead, to avoid making a mess.) Next, encourage her to walk across the paper to you. Then, repeat the process with your own feet, and walk normally over another sheet of butcher paper, several feet longer than the one you used for her. Now, examine the footprints that she and you left behind on the butcher paper. You can repeat this experiment several times, over the course of months or even years, to watch for changes in her walking pattern.
THE HYPOTHESIS
Shortly after your baby begins walking independently, step width (the distance between the left foot and right foot while you walk) will be about 25 percent shorter for you than for her, although chubbier bodies in both infants and adults will have wider step widths. In addition, your left and right feet will be nearly parallel, but hers will be turned out, possibly by as much as 40 percent. Your walking pattern will be much straighter than hers, and even accounting for leg length, her step lengths will be smaller than yours.
THE RESEARCH
The development of walking skills has been extensively studied, with a focus on when and how walking begins and progresses. A 2009 study attempted to build on this body of research by trying to determine why walking improves. Specifically, researchers examined whether improvements in walking skills can be attributed to developmental maturation, practice, or changes in body type. They studied the walking patterns of babies, kindergarteners, and adults using the technique described above, in which inked tabs were placed on the subjects’ shoes. They found differences in step length beyond that which would be explained by accounting for leg length, step width, foot rotation (whether toes point in or out), and dynamic base, a measure of the straightness of walking determined by calculating the angle of three consecutive steps. They then looked for correlations between these differences and the subjects’ ages, amount of practice walking, and body types. They found that a baby’s amount of practice walking, which could be roughly measured by calculating the time since the baby started walking, had a large effect: Babies with the most practice had walking patterns more similar to adult walking patterns. Age and changing body types, on the other hand, had little effect on their own.
The study’s authors note that walking researchers in earlier decades had considered age, an indirect measure of brain maturation, to be the most important factor in walking improvements. But since the 1980s, researchers have focused more on their subjects’ level of walking experience. The results of this study confirm that walking experience is indeed the more salient factor. They point out that in the course of a normal day, independent walkers might take thousands of steps across a variety of different terrains—carpet, tile, hardwood, grass, concrete—and each is a new opportunity to refine their walking technique.
THE TAKEAWAY
Walking is an activity that your baby will need little encouragement to practice, once she gets the hang of it. Expect her to zoom around whatever area she’s allowed to explore, whether it’s a tiny room or a wide-open space. During the times when she’s bouncing off the walls, it’s good to remember that, as with many other aspects of child development, the amount of practice your child gets will have the biggest impact on her progress. So, though it may be faster (and less dizzying) to get from Point A to Point B with her in your arms, try to give preference to letting her walk on her own.
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Familiarity and Foods
Age range: 12 months
Experiment complexity: Moderate
Research area: Social development
THE EXPERIMENT
Recruit two friends, including one who speaks a foreign language, to help you with this experiment. Prepare two sweet foods, such as applesauce and pureed apricots, and place each in a separate bowl. Have your English-speaking friend hold one of the bowls, smile, and say to your baby, “This is one of my favorite foods to eat.” Then, have your friend taste a spoonful of the food and say, “Yummy!” Next, with a baby spoon, offer some of the food to your child. Now, direct your other friend to do the same thing with the other bowl, but speaking in a foreign language. Then, offer some of the second food to your child. Finally, both of the friends should simultaneously offer their bowls to your baby.
THE HYPOTHESIS
Your baby will choose the bowl of food offered by the English-speaking friend.
THE RESEARCH
Babies have pretty low standards about the things they’ll put in their mouth: They tend to follow the “if it fits in there, I’ll try it” diet. It might, at first blush, seem strange that natural selection hasn’t given them more discriminating eating habits—after all, you eat something toxic as an infant and you won’t be around to reproduce. But bear in mind that in the early years of life, humans depend
on others to feed them, and so they don’t really have to deal with the problem of food selection; their foods are selected for them. Indeed, this sometimes works to parents’ advantage because at 12 months a baby will be willing to try veggies that a year later he’ll refuse to touch.
A 2009 study tested 12-month-old babies for whom English was the primary language spoken at home. The babies watched as two women each presented a food choice. One woman spoke English; the other spoke French. Both tasted and expressed delight with the foods, and most of the babies tried each food when it was individually presented to them. But when the babies were given a choice between the two foods, a majority, about 60 percent, chose the food that had been associated with the English-speaking woman, while only about 25 percent chose the food that had been associated with the French-speaking woman. (The experimenters controlled for conditions such as which language was spoken by the woman, which food was associated with the woman, and which order the languages were presented.)
The babies in the study used language familiarity as a social cue that either imparted a preference where no preference existed or overruled an only slightly developed preference based on taste. The study offers evidence that the earliest expressions of food preference use these social cues as a bridge between the very low discrimination shown before a child reaches his first birthday, and the more refined preferences, based on the qualities of the food itself, that emerge later.
THE TAKEAWAY
Savor these moments, in which subtle social cues can persuade your baby to try the vegetables on his plate. In but a few short years, neither heaven nor earth will be able to convince him. In the meantime, try to expose him to the widest variety of foods you can. As for your baby’s preference for native speakers, it’s a normal part of his language development, not evidence of xenophobia. In fact, because babies and young children are much better at picking up new languages than we adults are, now’s a great time to expose him to a foreign tongue, particularly because multilingual workers are likely to be in even higher demand by the time your baby reaches adulthood.
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The Retriever
Age range: 11–13 months
Experiment complexity: Simple
Research area: Motor skills
THE EXPERIMENT
Conduct this experiment around 11 months, or when your baby is an experienced crawler but not yet a walker. During a long session of uninterrupted playtime with your baby (an hour or more), observe the way he interacts with objects. If he crawls to an object across the room, does he play with it or share it while remaining in the place where it was discovered, or does he retrieve it by crawling back to you to play with it or share it?
THE HYPOTHESIS
The more your baby retrieves—that is, he crawls to a distant object, then crawls back with the object in hand—and the more he shares the retrieved object, the more likely he is to walk by 13 months.
THE RESEARCH
In a 2011 study, researchers observed a group of 11-month-old experienced crawlers, none of whom had begun walking yet, during unstructured playtime with their mothers in a home setting. The researchers returned to the homes two months later and again observed the babies, about half of whom had begun walking. They found that the babies who were walkers at 13 months had been more likely, at 11 months, to crawl to distant objects, carry objects, and share objects with their mothers. For instance, the walkers had, at 11 months, crawled to distant objects about twice as frequently as the nonwalkers had. They had also carried objects nearly five times as much as the nonwalkers had. And although only a small number of infants (about 15 percent) exhibited retrieval behavior, nearly all of the ones who did were walking two months later.
The researchers noted that once the infants did begin to walk, their willingness to pursue distant objects and to carry objects increased substantially—which stands to reason because walking enables them to get places faster and to have their hands free to carry things. They concluded that the desire to do these things at 11 months is likely to motivate the babies to begin walking sooner.
THE TAKEAWAY
You may be eagerly hoping that your baby turns out to be an early walker. Or—especially if this isn’t your first child—you might be dreading the day he becomes bipedal and able to zoom away even faster. In either case, if you see him acting like a golden retriever during playtime, you’d better charge up those camera batteries. His first step is likely on its way soon!
Tools of the Trade
One high-tech method researchers use to determine a baby’s response to an image, sound, or other stimulus is to measure her brain’s electrical activity by placing electrodes on her scalp, a process called electroencephalography (EEG).
For instance, in one recent study, EEG data were collected during an experiment in which 7-month-old babies were shown a photograph of a woman’s face accompanied by the sound of her voice.
An analysis of the EEG data found that when the photo and the voice conveyed the same emotion (such as a smiling face and a cheerful tone of voice), it produced one type of brain wave, and when the photo and the voice conveyed different emotions (such as a smiling face and an angry tone of voice), it produced a different type of brain wave.
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I Know Something You Don’t Know
Age range: 13–15 months
Experiment complexity: Moderate
Research area: Cognitive development
THE EXPERIMENT
Place two same-size boxes on a table in front of your baby, with their openings facing each other, and place a small toy between them. Direct a friend to walk up to the toy, play with it briefly, then place it into one of the boxes, pausing with her hand in the box for a second or two before withdrawing it. Next, have the friend walk away briefly, then return and place her hand in the box with the toy in it for a few seconds. She should then withdraw her hand, leaving the toy inside. Now, have the friend leave the room. While she is out of the room, allow your baby to see you move the toy to the other box. Now, direct your friend to return to the room. Without looking into either of the boxes, she should reach into the one that previously contained the toy, and keep her hand inside the box for several seconds. Observe your baby’s reaction to her choice. A few days later, repeat the experiment, but this time, your friend should reach into the other box—the one that actually does contain the toy.
THE HYPOTHESIS
The second time you perform the experiment, your baby will be surprised that your friend reached into the box that now contains the toy because he doesn’t expect your friend to know that the toy has been moved. Because he is surprised, he will look at your friend’s final pose longer this time than he did the first time, when the friend reached, as expected, into the box where she had left the toy.
TWEAK IT
If you are able to perform the experiment on two babies of roughly the same age, you can assign one to each condition, rather than repeating the experiment a few days later. This will eliminate the possibility that your baby’s familiarization with the procedure might skew the results the second time around.
THE RESEARCH
In a 2005 study, 15-month-old babies were presented with a scenario much like the one described above. They looked significantly longer—almost 10 seconds more, on average—when the adult reached into the box that contained the toy than when the adult reached into the box that no longer contained the toy. A similar 2007 study found that babies as young as 13 months old also demonstrated surprise when an animated character made a choice about the location of an object that was inconsistent with the information available to the character.
Whether babies are able to understand the belief states of other people—that is, whether they can keep track of what true or false beliefs other people hold—has been a point of contention among psychology researchers. In a number of previous experiments, children did not demonstrate that they could recognize
the false beliefs of others until they were 3 or 4 years old. But the researchers who designed the 2005 study sought to eliminate aspects of those previous experiments that may have inhibited younger children. They purposefully constructed a sequence that was entirely nonverbal and relatively simple in its presentation.
The researchers concluded that the babies were able to grasp that the adult understood the toy to be in the first box, even though it was actually in the second box. They expected the adult to reach into the box that ostensibly contained the toy (the first box), and so it violated their expectation when the adult instead reached into the second box.
The results of this study suggest that an understanding of the belief states of other people is present at an age far earlier than what previous experiments had suggested. The researchers note that the study may lead to further developments in two particular areas of psychological research. The first is atypical development because previous experiments have shown that autistic children do poorly on false-belief tests. The second is animal cognition, for which an entirely nonverbal experiment might be useful to help determine whether animals are able to understand the belief states of people.