Around the world, people hold similar views about the
timing of cognitive development: Young children aren't capable of reason, and
don't make the shift to rationality until they are between 5 and 7 years old (Rogoff 1996).
Are their beliefs wrong-headed? Historically, there has been some research on their side. Piaget's landmark studies indicated that kids don't grasp logic until they are approximately seven years old (Inhelder and Piaget 1958). And classic "theory of mind" experiments suggest that young children are poor psychologists. They act as if they don't understand the perspectives of other people (Wimmer and Perner 1983; Perner and Rossler 2012).
But in recent decades, researchers have re-examined old assumptions and found reason for doubt. Kids, they say, may be confused by the experimental procedures. They may be puzzled by the unnatural wording of the test questions, or distracted by too many details.
And there is another possibility: All people, even highly-educated adults, experience misleading intuitions and cognitive biases. Getting the right answer depends on our ability to ignore these inner voices. So perhaps kids seem illogical because they have more trouble turning off their misleading intuitions.
Where's the evidence? Consider first the weird things that young children say.
Three crazy mistakes that young children make
Classic experiments show that young children regularly commit bizarre errors like these.
1. More red flowers or more flowers?
An adult shows a child a bunch of flowers. Four are red, two are white. The adult asks, “Are there more red flowers or more flowers?
Kids younger than six usually answer “There are more red flowers.”
2. Can other people possess false beliefs?
A child watches a puppet show about Maxi and his mother.
Maxi sees his mother put some chocolate in a blue cupboard. Next, Maxi goes out to play.
While Maxi is gone, his mother uses some of the chocolate to make
a cake. Then she puts the remaining chocolate in a new location – a green cupboard.
Then the puppeteer asks the child:
“When Maxi comes back, where will he look for the chocolate?”
Before the age of four, most kids say that Maxi will look for the chocolate in the new location, not the blue cupboard.
3. Does merely moving objects around change how many there are?
A four- or five-year-old examines two identical rows of coins. He
notes that each row contains the same number of coins. But when an adult
alters the top row--pushing together the coins so that the row appears
shorter--the child amends his assessment.
Now he says that the top row contains fewer coins.
Explaining the apparent irrationality of children
These outcomes have been replicated in populations around the world. What’s going on? Do the errors reflect limitations imposed by cognitive
development? Or does a child's performance depend on the ways we test
The answer seems to be a little of both. Let’s start with ways we test kids.
When interpreting questions, kids take context into account
It’s no surprise that children are sensitive to the social context of language--what linguists call “pragmatics.”
When adults ask kids weird questions—as they often do in experiments designed to test cognitive development—kids may wonder why.
Misunderstandings about logic....or about the adult questioner's meaning?
Consider the flower task. It’s from an experiment designed by Jean
Piaget, and it’s supposed to test whether or not kids understand class
inclusion or set theory, i.e., the idea that all the members of one set
(red flowers) can belong to another, more inclusive set (flowers).
But the question about flowers—“Are there more red flowers, or more flowers?” is weird. Real people don’t talk that way.
So maybe, the child reasons, the adult means something different when she speaks of “flowers.” Maybe the adult is really asking me to compare the red flowers with the white flowers.
Might this explain the error? One study changed the wording of the question to this:
“Here is a bunch of grapes. There are green grapes and there are
purple grapes, and this is the bunch. Who would have something more to
eat, someone who ate the green grapes or someone who ate the bunch?”
This is a more natural way of asking the question. And it seems to make a difference.
When kids were given this “natural language” version of the test, they did significantly better (Markman and Seibert 1976).
More recently, Usha Goswami and Sabina Pauen designed yet another way to test kids (Goswami and Pauen 2005).
In their experiment, they asked kids to “create a family” using
animal toys. This required that kids recognize one inclusive category
(the species) and two subcategories (big and small animals of the same
Next, the kids were asked to extend the idea to inanimate
objects, like blocks and balloons. The children, who were four- and
five-year-olds, performed much better on this task than on the original,
Piagetian flower task.
“Theory of Mind” errors
Remember the puppet show about Maxi and his mother? That scenario is designed to test a child’s “theory of mind” skills.
Does the child assume that his own thoughts, beliefs, and desires
are shared universally by everyone? Or does he understand that other
people have minds of their own--and may believe things that he himself
knows to be false?
As noted above, kids younger than four years tend to have trouble
with the hidden chocolate problem. When asked where an ignorant
character will look for the chocolate, the kids give the wrong answer.
They claim that the character will look where the chocolate really is,
not where the character should believe it to be.
This might indicate that two- and three-year-olds don’t attribute mental states to other people. A pretty disturbing thought! But experiments suggest that even 15-month-old
babies understand something about false beliefs (Onishi and Baillargeon
2005; Perner and Rossler 2012). So why do young children fail the Maxi false belief task?
Michael Siegal and Katherine Beattie (1991) wondered if kids
misunderstood the question. Maybe kids thought they were being asked
where Maxi should look for the chocolate.
So the researchers changed the question. Instead of asking “Where will Maxi look for the chocolate?” they asked
“Where will Maxi look first for the chocolate?”
With this new wording, even three-year-olds tended to get the right answer most of the time.
These results are consistent with another explanation, too: Maybe
the original puppet show was just too complex, and kids got distracted
by extraneous details.
Paula Rubio-Fernández and Bart Geurts argue that several features
of the show may have prevented kids from tracking Maxi's perspective.
It's not clear at the beginning who the protagonist was, and Maxi left
the scene for much of the story while his mother made a cake. Also, at
the end, "the experimenter switched roles from puppeteer to interviewer
to spring his question on the unsuspecting child." Any of these details
might disrupt a young child's attempt to keep track of what Maxi
To test their explanation, Rubio-Fernández and Geurts created a
simpler puppet show with fewer distractions. They also made sure that
kids were paying attention to the fact that the protagonist couldn't see
what was going on when the treat was moved. Under these conditions, 80%
of three-year-olds got the right answer when asked what the protagonist
would do next (Rubio-Fernández and Geurts 2013).
What about the last example—the one with the two rows of coins?
This is another task developed by Piaget, and it’s supposed to test a child’s understanding of conservation, the idea that some properties (like the number of items in a set) don’t change because we merely move things around.
A principle of physics? Yes. But it’s about basic reasoning, too.
As David Elkind and Eva Schoenfeld (1972) noted, the conservation task
requires us to use that fundamental tool of deduction, the transitive
1. Row 1 = Row 2
2. Row 1 = Row 1A (in which where the coins are pushed closer together)
3. Row 1A = Row 2
So it’s not just that kids haven’t worked out the rules of our physical universe. There seems to be a failure to apply logic.
But social context may play a role here, too.
Imagine you’re the child being tested.
You’ve just told the adult that both rows contain the same number of coins.
Next, the adult takes the coins in the first row and changes the
spacing between them. Then she asks you the same question again—are
there “more, less, or the same in each row?”
What are you to think?
Ordinarily, you’d assume that the number hasn’t changed. But why would this authority figure ask such an obvious question?
Maybe--for some unknowable reason--she wants or expects you to change your original answer. So you do.
Could this explain why many kindergartners have failed the conservation task? It might explain part of the phenomenon.
James McGarrigle and Margaret Donaldson gave the classic
conservation task a tweak. After the child inspected the two rows and
acknowledged that they were equivalent, the experiment was “interrupted”
by a “naughty” teddy bear who shifted the coins. The adult scolded the
bear and asked the question again.
In this scenario, even four-year-olds tended to get the right answer (McGarricle and Donaldson 1975).
These results have been questioned by some researchers. Maybe the
teddy bear distracted kids so much that they didn't bother to rethink
And if you look at the demonstration video (which shows several
standard Piagetian conservation tasks), perhaps you can see why some
people don't believe that kids are in conflict.
I'm not an expert reader of body language. But to my untrained eye, these girls seem pretty sure of themselves. On the other hand, they also seem very eager to please! Do they really believe the quantities have changed? Or are they convinced that the woman wants them to change their answers?
So does social context account for all the errors?
No. The context of language--pragmatics--is an important aspect of
any experiment that involves communication. And today’s researchers pay
close attention to the ways that pragmatics might influence children’s
behavior. But pragmatics can’t explain away all the mistakes we see young children make. Other factors play a role including these:
Experience helps. A study of first graders suggests that
kids benefit when they are explicitly trained to solve classification
problems (Pasnak et al 2006)—a finding that's consistent with the notion
that logic and critical thinking must be taught.
Theory of mind skills also develop over time. Even adults have trouble with certain versions of the false-belief task (Birch and Bloom 2007).
But perhaps the most important factor isn't working memory, or even a child's prior understanding of the world. Instead, it's a form of self-restraint: An individual's ability to ignore easy -- but misleading -- intuitions.
People of all ages use simple heuristics, or rules-of-thumb, to solve everyday problems. It's a mode of "fast thinking" that rewards us with quick, intuitive answers (Kahneman 2011). But sometimes it leads us astray. For instance, consider this heuristic:
"If there is a row of objects, use the length of that row to estimate quantity.”
This is usually a good rule-of-thumb, which is why people use it when deciding which line to stand in at the supermarket. But in the conservation experiment with the coins, the rule backfires. To get the right answer, you must selectively ignore the "length-equals-number" heuristic, and that requires conscious attention or inhibitory control.
Adults do it with effort. But young children have particular trouble blocking these knee jerk, rough-and-ready guesstimate strategies (Houdé and Bourst 2014).
Resisting your gut reactions
Do kids make logical errors because they can't turn off their "fast thinking" intuitions? Olivier Houdé and his colleagues have championed the idea, and it explains a lot.
For example, consider
the Stroop effect, which shows that people
take longer to answer questions when those questions contain
distracting elements. Even when you know that the distractions are
irrelevant, some part of your mind is captivated by them. Too see what I
mean, try answering quickly:
Which of these animals is larger in real life?
Because the rabbit looks larger, part of your mind wants to
answer “rabbit.” To get the right answer, you must inhibit that impulse,
which takes extra effort and time.
Kids are slower at these sorts of tasks, and brain research
suggests why. For kids, the brain activity associated with the
incorrect response (e.g., the rabbit) is stronger and longer-lasting
than it is for adults (Szucs et al 2009). Moreover, there is less activity in key areas of the prefrontal cortex, brain regions associated with inhibitory control (Houdé and Borst 2015; Borst et al 2013). These areas are "under construction" in young children, and continue to develop throughout later childhood and adolescence (Casey et al 2005).
So kids really do know that elephants are bigger than rabbits, and they are capable of understanding that 5 coins don't become 6 coins merely because we move them around. But they have more trouble inhibiting the wrong answer. Their internal censor--the executive function that stops us from blurting out silly things--isn’t as powerful.
That's an important developmental constraint on reasoning, but it doesn't mean kids are fundamentally irrational or illogical.
Indeed, as Houdé and Gregoire Borst point out, young babies routinely pass tests of number conservation in the laboratory. They seem to understand that moving objects around can't change their number, and they don't have to inhibit the "length-equals-number" heuristic. They haven't learned it yet! We acquire intuitions and rules-of-thumb throughout our lives, and
frequently have to chose between trusting these heuristics or taking a more
effortful, careful approach to problem-solving. Adults, like children, can get
it wrong, and we all benefit from learning to scrutinize the easy answers.
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