Cognitive Daily reports nearly every day on fascinating peer-reviewed developments in cognition from the most respected scientists in the field.
Greta Munger is Professor of Psychology at Davidson College whose works include The History of Psychology: Fundamental Questions. Dave Munger is co-founder and president of ResearchBlogging.org and a writer whose works include Researching Online. And yes, he is married to Greta.
Jim was an early, confident walker. Greta likes to say that he didn't learn to walk, he went straight to running. By the time he was about 16 months old, he could already outrun his already-pregnant mother.
Nora, on the other hand, was a late, tentative walker. She took her first steps at around 12 months, and still wasn't very confident as a walker at 18 months. In this photo, at 17 months, she still clings to their toy kitchen set for balance.
But I've just finished reading a fascinating study suggesting that at 14 months, when both of them were walking -- Jim with confidence, and Nora struggling -- they actually took a similar approach to balance while walking.
A team led by Jessie Garciaguirre might be the first to investigate how infants who've only recently learned to walk adapt to carrying heavy loads. Adults generally carry no more than 35 percent of their own body weight (though in some African tribes, women balance immense loads -- up to 70 percent of their body weight -- on their heads). School-age kids might port 20-30 percent of body weight in backpacks on their way to school. Adults and kids make significant adjustments to posture and gait when bearing loads in excess of 15 percent of body weight. They take shorter steps, and they lean away from the load to compensate (generally this means leaning forward to accommodate a backpack).
So why not put backpacks on toddlers and see how they manage? Garciaguirre and Karen Adolph had previously found that 14-month-olds fall down an average of 15 times per hour while playing. What could possibly go wrong when heavy weights are strapped to their backs?
Ask almost anyone whether willfully deceiving another person -- lying -- is wrong, and they'll say it is. But probe a little deeper and most people will say there are some instances where lying is okay: lying to prevent a crime or an injustice is acceptable, just not lying for personal gain. Parents teach their kids that lying is wrong, and punish them for telling lies.
I can still remember the shock when my parents "lied" about my sixth birthday (which was a day away) at an ice-cream parlor so I could get a free sundae. But eventually, at some point, most American kids end up telling lies to their parents, as did I -- I just can't remember any of them at the moment (honest!).
Clearly children's conceptions of "acceptable" lies change over time. There must be a time in early childhood where they don't understand what a lie is. Then they learn what a lie is, followed shortly by learning that a lying is wrong. But how do they move from this stage to the more nuanced moral assessment of lying held by most adults?
Serena Perkins and Elliot Turiel came up with six situations in which lying might be justified, then asked 64 teens aged 12 to 17 which ones were acceptable and which were not. The situations are below:
One of the amazing things about learning language is that children rarely hear language sounds in ideal acoustic environments. Maybe other people are talking in the background, or the dishwasher is running, or the TV is on. Yet somehow children they learn words just the same. By the time we're adults, we've become experts at filtering out irrelevant sounds and patching together meaning out of the cacophony of everyday life.
As one example, listen to this short clip of me saying the word "dinosaur" three times.
I edited the "s" sound out of the first "dinosaur," so you can clearly hear me saying "dino_aur." The last "dinosaur" is obviously complete. But what about the middle "dinosaur," where I edited in a cough/sneeze right over where the "s" sound is supposed to be? Can you still hear the "s" in the background? Let's make this a poll:
Most adults believe they hear the "s" sound in cases like this, even if the sound has been edited out: the perceptual system adds in a sound where it doesn't exist. (Did I edit the sound out here? I'll keep that a mystery for now.) The effect, known as perceptual restoration, has been observed in children as young as five years old.
But what about younger children -- kids who are just beginning to learn language? Do they also exhibit perceptual restoration? It's a difficult question to study, since children who only know a few words aren't able to tell us what they hear with the precision needed (they can't read, so how can they tell us whether they heard an "s" sound?).
The fact that infants are able to learn language without any help from adults can sometimes seem almost miraculous. Not only do children learn to speak and understand language completely on their own, active teaching of language skills seems to make almost no difference in their ability to talk.
One of the first difficulties when learning a language solely from listening to spoken language is determining where one word ends and the next one begins. Native speakers of a language typically leave no audible space between words at all. Even "motherese" doesn't leave any space between words -- if anything the spaces are diminished: "issntdatacutewittlebaby!"
So how do babies learn where one word ends and the next one begins? A group of researchers including Luca Bonatti, Marina Nespor, Jacques Mehler, and Juan Toro, believes it has identified a key pattern that works in a wide range of languages: language learners look to patterns in the consonants for information about where words start and end; they look to vowels to understand the role of words in a sentence. The first part of their explanation was explored in 2005. Their newest paper, led by Toro, considers the second part of the problem. How did they do it? They invented a "language" that had a couple of very simple rules. See if you can figure out the rules by looking at the list of "words" below:
There is a growing body of evidence that very young children -- too young even to talk -- still know plenty of words. When our kids were very young, it was quite clear that they knew the meanings of many more words than they could actually produce. When they couldn't speak at all, they understood words like "Mommy," "bottle," and "diaper." When they were older and could say those words but not complete sentences, they understood more complicated phrases like "go into the kitchen and bring me your sister's sippy cup."
But is there something special about words? Or could babies learn to associate any sound with a meaning? So far the evidence suggests that words are special. Twelve-month-olds, for example, can be trained to recognize words much more quickly than other sounds. But still, this might be due to the fact that these babies have themselves already learned a considerable amount of language. Do younger babies show the same preference for words over other sounds?
Anne Fulkerson and Sandra Waxman enlisted 128 infants -- half of them six months old, and half twelve months old -- and showed them each eight slide-show pictures of either dinosaurs or fish. With each picture, half the babies heard a recording of a woman's voice identifying the picture with a nonsense word, like this: "Look at the toma! Do you see the toma!" The other babies heard a series of tones at a constant pitch for the same duration as the woman's voice. After viewing the series of pictures -- either eight different dinosaurs or eight different fish, they saw one final slide with both a picture of a dinosaur and a fish (neither of which they had seen before).
What makes children so cute? Is it their adorably soft skin? Their innocently mischievous smiles? Their oversized eyes and tiny little mouths? Why is it that some kids are singled out for TV commercials and child beauty pageants, while others don't seem to be noteworthy in any way?
Attractiveness in children isn't trivial -- teachers believe more attractive students are more intelligent, and are less likely to punish them for misbehavior. There are also gender differences: Teachers give better grades to attractive girls, but worse grades to attractive boys.
Most studies about cuteness have focused on photographs of children. For example, in the grading study I mentioned above, photos of attractive and unattractive kids were included with essays to be graded by teachers. But when a Japanese team led by Reiko Koyama asked 38 volunteers to tell them what made a child cute, many of the responses were focused on actions: When a child shares with a friend, or imitates adult behavior, or hides in shame, all these things are seen as cute. Out of 148 different examples of cuteness, the researchers selected the 29 most reliable factors, which they divided into four categories: Childlike behavior, physical cuteness, imitating adults, or invoking protective feeling in others.
When adults are asked if they remember pictures of faces, they're more accurate when the faces are the same race as they are. It makes some sense -- people are likely to spend more time with and have more same-race friends, so they may become better attuned to the differences in individuals in their own racial group. This finding can be especially important in eyewitness testimony: If a crime victim identifies his assailant as someone of a different race, then the research suggests that this identification is more likely to be problematic than an identification of a same-race suspect.
But what about kids? Younger children have less experience, so maybe they don't show the same bias in their ability to recognize different-race faces. While some studies have shown the same pattern in children as adults, an intriguing 1982 study led by J. Chance actually found that there was less of a bias in young children than in older children. Could it be that the bias is actually acquired over the course of childhood?
B. Corenblum and Christian Meissner felt the matter deserved more study, especially because they had identified some problems with the Chance team's study. In that study, kids were shown photos clipped from college yearbooks. Later the kids saw those same pictures mixed in with previously unseen photos, and were asked which pictures they had seen before. It could be that the kids were recalling clothing items or artifacts in the pictures instead of the actual facial features.
You're trapped inside a rectangular room with four doors, one in each corner. You try the first door. It's locked. You try the second and the third door -- locked again. Finally the fourth door opens. You make a point of remembering which corner of the room it's in, which turns out to be useful, because before you know it you're trapped in another identical room. Now, how did you remember what door opened last time? You can't rely on your physical orientation because you might be facing a different direction.
Suppose one wall in both the rooms was a different color from the rest. Then it would be easy to locate the correct door based on this feature. If not, you'd have to rely on the shape of the room. Take a look at the two rooms below. If door 4 is always unlocked, then it should be easier to find in room B than in room A.
If you're placed in a series of rooms like room A, facing a different direction each time, then you wouldn't be able to tell the difference between door 4 and door 2: both doors have a short wall to the left and a long wall to the right. If the rooms always look like room B, it shouldn't take long to learn to pick door 4 every time -- it's always just to the left of the green wall. But still, even in room A, eventually you'd learn to avoid doors 1 and 3 -- they're never going to be unlocked.
Two facts are true about young children: they sleep a lot more than adults, and they learn language at an astonishing rate. How can they learn so much when they're sleeping so much of the time? Perhaps sleep itself enhances learning. In fact, a number of studies suggest that naps actually enhance learning in adults. What about kids?
A team led by Rebecca Gómez developed a clever test to see if 15-month-olds learn language faster when they've had a nap. At 15 months, most infants understand a lot of language, but don't produce much. But of course, each baby learns at a slightly different rate. How is a researcher to know if the child is learning new words over the course of an experiment, or just reflecting previous knowledge? And if the child can't say much at all, how does the experimenter determine that a word or concept is learned?
The first problem was solved in several previous studies led by Gómez: the researchers used an artificial language -- or rather, just a small portion of a "language." In English we might say "a bird quickly flies," but we'd say "birds quickly fly." The ending of the phrase changes depending on what's said at the beginning of the phrase. The artificial language created an analogous situation:
pel wadim rud vot kicey jic pel puser rud vot fengle jic pel coomo rud vot loga jic pel gople rud vot taspu jic
So phrases starting with pel always end with rud and phrases starting with vot always end with jic, while the nonsense words in the middle of the phrase can change. Can babies learn this pattern? And does napping make a difference?
When we first moved to the small suburban town we still live in, we quickly realized we needed to buy a second car. Nora and Jim were just one and two and a half years old, only barely beginning to understand language. After we made our purchase, sometimes we drove in the old car (a Subaru station wagon), and sometimes in the new car (a Plymouth minivan). Since neither child could pronounce words as complicated as "minivan," they had to come up with their own way to refer to the vehicles. They called the Subaru the "red car" and the van the "blue car."
But there were many other ways they could have referred to each vehicle. They could have said "new car" and "old car," "big car" and "little car," or even just "van" and "car." Why did they refer to them by color?
Most research on young children's word choice in ambiguous situations like this has focused on locating objects. Do you say the car is "on the driveway" or "outside the house"? This doesn't address those other possibilities, such as size, shape, or color. One researcher, Graeme Halford, has speculated that children use the words which require simpler reasoning. "The dog is brown" requires simpler logic than "the dog is bigger than the cat." Even more complex is a statement such as "The chair in the living room is softer than the chair in the dining room." Similarly, while Jim and Nora had both learned colors, they hadn't yet learned how to categorize station wagons and minivans. Any object which transported people around on streets was a "car."
Although this explanation seems reasonable, no one had confirmed it experimentally until Jodie Plumert and Penney Nichols-Whitehead asked 3- and 4-year-olds to hide a tiny toy mouse in a dollhouse while a toy troll hid behind the house. The idea was to find out which words the children used to explain to the troll where to find the mouse. Here's a picture of the house:
Take a look at this slideshow (QuickTime required). You'll first see a photo in perfect focus. Then 12 more pictures will flash by, each of them blurred using Photoshop. Finally, the original photo will appear again. Is it the same as before, or slightly blurrier or sharper?
I'll give the answer after a few readers have had a chance to make a guess in the comments. Most people with normal vision will gradually adapt to blurry photos (though it might take a little longer than I've allowed in this movie). Then when they see a photo that's in focus, it seems too sharp -- as if it's been artificially sharpened like this picture:
Photos that are slightly out of focus (though not as blurry as the set of blurry photos they adapted to) will seem just right. But what about older individuals, whose eyes are less sensitive to contrast and brightness, and whose visual systems in the brain may also have degraded?
A team led by Sarah Elliott showed sequences similar to the movie above to 10 young adults (average age 25) and 10 older adults (average age 74). Their sequences were much longer (about 2 minutes), and several tests were administered, with blurred, neutral, and sharpened images. At the end of the sequence, the viewers were asked if the properly focused image seemed too blurry or too sharp.
At least once or twice a week at dinnertime, our family has what we call a "harmony meal." Jim and Nora are good eaters with broad tastes, but they both (along with me and Greta) also have some foods they don't like. A harmony meal is a meal where everyone in the family likes every dish we serve. These aren't necessarily the healthiest meals (spaghetti with meat sauce and garlic bread is a favorite), but it's nice to have a meal where everyone's happy about what's being served.
When we're not having a harmony meal, we all still manage to find something we'll eat -- and our kids understand that if they don't want to eat dinner, then they'll just have to wait until breakfast. But everyone knows horror stories of kids that simply won't eat anything except for McDonalds' French fries, or Dad's macaroni and cheese, or Grandma's cookies, when their parents would really prefer chicken piccata with couscous and asparagus. Were these kids just raised badly? Or do they literally have different tastes than their parents?
It turns out that researching the relationship of parents' tastes with those of their kids is a difficult proposition. Some researchers have tried presenting families with lists of foods and asking them to rate how much they like and dislike each food. The parent's tastes might correlate with those of their kids (and they did, in several studies), but does that reflect parental influence on the child, or the larger influence of society on the entire family? And isn't any list of food by definition limited?
Here's a picture of our daughter Nora at about 3 months of age. She looks like she's fairly aware of the events going on around her (arguably more aware than she sometimes appears now, at age 12). However, as our knowledge of how infants begin to perceive the world around them has increased, we've learned that the world of a three-month-old literally looks different to them than the world we perceive as adults. That's because vision, which seems so obvious and instinctive, is actually an active process. When we perceive the world visually, we're not just passively "seeing" what's there, we're constantly determining where one object ends and the next one begins. We're applying logical rules to help break objects into groups and understand how the two-dimensional image on the inside of our eye corresponds to a three-dimensional physical world.
In the picture of Nora, for example, how do we know that the bonnet isn't part of her body? Because it's a different color, white? But the white buckle is part of the baby carrier. Clearly the set of rules we've learned are not simple. But when do we learn them? And in what order?
One of our readers emailed us asking if there has ever been research on whether kids' understanding of numbers -- especially large numbers -- differs from adults. Greta did a little poking around and found a fascinating study on second- and fourth-graders.
In the U.S. (and I suspect around the world), kids this age are usually taught about numbers using a number line. In first grade, they might be introduced to a line from 0 or 1 to 10. In second grade, this is typically expanded up to 100. But what happens when second-graders are asked to place numbers on a line extending all the way up to 1,000?
This happens:
I've placed the 500 (in gray) on these lines for reference; in the real study, conducted by John Opfer and Rober Siegler, the kids used lines with just 0 and 1000 labeled. They were then given numbers within that range and asked to draw a vertical line through the number line where each number fell (they used a new, blank number line each time). The figure above represents (in red) the average results for a few of the numbers used in the study. As you can see, the second graders are way off, especially for lower numbers. They typically placed the number 150 almost halfway across the number line! Fourth graders perform nearly as well as adults on the task, putting all the numbers in just about the right spot.
What do most parents want for their kids as they grow into adults? Successful careers? Happy family lives? Or do they simply want their children to be good people? They probably want all of these things -- and a little wealth and fame wouldn't hurt either. The bigger question parents have is about the right way to inspire, motivate, cajole, or prod their kids in the direction they believe is most likely to yield the desired results.
There's been a lot of research about good parenting, but much of that research has focused on parenting style: parents' overall philosophy of childrearing, such as how strict or emotionally expressive they are with kids. When studies have focused on actual parental behavior, they tend to study only discipline: how parents respond when kids misbehave.
But clearly there's much more to parenting than this -- there are lots of ways we try to encourage our kids to become the kind of adults we want them to be. According to a team led by Gustavo Carlo, few studies have addressed parenting practices and moral behavior. They've recently completed a survey that they see as the first step to covering this ground.
Children follow a consistent pattern when they acquire language. Instead of learning the most common words first, they start by learning a disproportionate number of nouns. In the youngest talkers nouns form up to 60 percent of their vocabulary, compared to just 40 percent of the vocabulary of a typical 2 and a half year-old (who now knows over 600 words).
This pattern applies in many different languages, even Mandarin and Korean, where verbs appear in more prominent positions in sentences. The phenomenon is so universal that it has led some theorists to speculate that acquisition of non-noun forms is simply beyond the cognitive ability of infants -- they have to "grow into" using verbs. But there's another possible explanation: it could be that anyone learning a language is going to learn nouns first, simply because that's the easiest way to learn language. In this view, the early dominance of nouns has nothing to do with general cognitive ability and everything to do with the process of language learning.
One way to distinguish between the two explanations could be to look at second-language learners. An older child -- or even an adult -- learning a language clearly has the cognitive ability to understand all types of words. But people learning second languages usually learn them differently from infants: they receive formal instruction; they memorize lists of words. Babies are never "taught" language -- they acquire it naturally by watching others speak.
A team led by Jesse Snedeker realized that one population might be able to cast some light on the issue: Children adopted internationally. More than 20,000 kids are adopted in foreign countries and brought to the U.S. each year. If they're adopted before reaching school age, they learn language in the same way as infants: by watching others speak, rather than formal instruction. Snedeker's team located 27 recently adopted children between two and a half to five and a half years old and tested their language abilities every three months until they had been in the U.S. for 18 months.
Cognitive Daily reports nearly every day on fascinating peer-reviewed developments in cognition from the most respected scientists in the field.
Jim was an early, confident walker. Greta likes to say that he didn't learn to walk, he went straight to running. By the time he was about 16 months old, he could already outrun his already-pregnant mother.
Here's a picture of our daughter Nora at about 3 months of age. She looks like she's fairly aware of the events going on around her (arguably more aware than she sometimes appears now, at age 12). However, as our knowledge of how infants begin to perceive the world around them has increased, we've learned that the world of a three-month-old literally looks different to them than the world we perceive as adults. That's because vision, which seems so obvious and instinctive, is actually an active process. When we perceive the world visually, we're not just passively "seeing" what's there, we're constantly determining where one object ends and the next one begins. We're applying logical rules to help break objects into groups and understand how the two-dimensional image on the inside of our eye corresponds to a three-dimensional physical world.
