Mindful of Symbols
On the way to learning that one thing can represent another, young children
often conflate the real item and its symbol. These errors show how difficult
it is to start thinking symbolically
By Judy S. DeLoache
About 20 years ago I had one of those wonderful moments when research takes
an unexpected but fruitful turn. I had been studying toddler memory and was
beginning a new experiment with two-and-a-half- and three-year-olds. For the
project, I had built a model of a room that was part of my lab. The real
space was furnished like a standard living room, albeit a rather shabby one,
with an upholstered couch, an armchair, a cabinet and so on. The miniature
items were as similar as possible to their larger counterparts: they were
the same shape and material, covered with the same fabric and arranged in
the same positions. For the study, a child watched as we hid a miniature
toy--a plastic dog we dubbed "Little Snoopy"--in the model, which we
referred to as "Little Snoopy's room." We then encouraged the child to find
"Big Snoopy," a large version of the toy "hiding in the same place in his
big room." We wondered whether children could use their memory of the small
room to figure out where to find the toy in the large one.
The three-year-olds were, as we had expected, very successful. After they
observed the small toy being placed behind the miniature couch, they ran
into the room and found the large toy behind the real couch. But the
two-and-a-half-year-olds, much to my and their parents' surprise, failed
abysmally. They cheerfully ran into the room to retrieve the large toy, but
most of them had no idea where to look, even though they remembered where
the tiny toy was hidden in the miniature room and could readily find it
there.
Their failure to use what they knew about the model to draw an inference
about the room indicated that they did not appreciate the relation between
the model and room. I soon realized that my memory study was instead a study
of symbolic understanding and that the younger children's failure might be
telling us something interesting about how and when youngsters acquire the
ability to understand that one object can stand for another.
What most distinguishes humans from other creatures is our ability to create
and manipulate a wide variety of symbolic representations. This capacity
enables us to transmit information from one generation to another, making
culture possible, and to learn vast amounts without having direct
experience--we all know about dinosaurs despite never having met one.
Because of the fundamental role of symbolization in almost everything we do,
perhaps no aspect of human development is more important than becoming
symbol-minded. What could be more fascinating, I concluded, than finding out
how young children begin to use and understand symbolic objects and how they
come to master some of the symbolic items ubiquitous in modern life. As a
result of that fortuitous model-room experiment, I shifted my focus from
memory to symbolic thinking.
Pictures Come to Life
The first type of symbolic object infants and young children master is
pictures. No symbols seem simpler to adults, but my colleagues and I have
discovered that infants initially find pictures perplexing. The problem
stems from the duality inherent in all symbolic objects: they are real in
and of themselves and, at the same time, representations of something else.
To understand them, the viewer must achieve dual representation: he or she
must mentally represent the object as well as the relation between it and
what it stands for.
A few years ago I became intrigued by anecdotes suggesting that infants do
not appreciate the dual nature of pictures. Every now and then, I would hear
of a baby who tried to pick up a depicted apple or to fit a foot into a
photograph of a shoe. My colleagues--David H. Uttal of Northwestern
University, Sophia L. Pierroutsakos of St. Louis Community College and Karl
S. Rosengren of the University of Illinois at Urbana-Champaign--and I
decided to investigate even though we assumed such behaviors would be rare
and therefore difficult to study. Fortunately, we were wrong.
We began testing infants' understanding of pictures in a very simple way. We
put a book containing highly realistic color photographs of individual
objects in front of nine-month-olds. To our surprise, every child in the
initial study, and most in our subsequent studies, reached out to feel, rub,
pat or scratch the pictures. Sometimes the infants even grasped at the
depicted objects as if trying to pick them up off the page.
We had a unique opportunity to see how universal this response was when
anthropologist Alma Gottlieb of the University of Illinois took some of our
books and a video camera to a remote Beng village in Ivory Coast. The
testing situation there was different: Beng babies sat on the ground or in
their mother's lap as chickens and goats wandered around and other children
and villagers played, worked, talked and laughed nearby. Yet the Beng
babies, who had almost certainly never seen a picture before, manually
explored the depicted objects just as the American babies had.
The confusion seems to be conceptual, not perceptual. Infants can perfectly
well perceive the difference between objects and pictures. Given a choice
between the two, infants choose the real thing. But they do not yet fully
understand what pictures are and how they differ from the things depicted
(the "referents") and so they explore: some actually lean over and put their
lips on the nipple in a photograph of a bottle, for instance. They only do
so, however, when the depicted object is highly similar to the object it
represents, as in color photographs. The same confusion occurs for video
images. Pierroutsakos and her colleague Georgene L. Troseth of Vanderbilt
University found that nine-month-olds seated near a television monitor will
reach out and grab at objects moving across the screen. But when depicted
objects bear relatively little resemblance to the real thing--as in a line
drawing--infants rarely explore them.
By 18 months, babies have come to appreciate that a picture merely
represents a real thing. Instead of manipulating the paper, they point to
pictures and name objects or ask someone else for the name. Melissa A.
Preissler of Yale University and Susan Carey of Harvard University recently
provided a good example of this development. The two researchers used a
simple line drawing of a whisk to teach 18- and 24-month-olds the word for
this object that they had not seen before. Most of the children assumed the
word referred to the object itself, not just to the picture of it. In other
words, they interpreted the picture symbolically--as standing for, not just
being similar to, its referent.
One factor we think contributes to the decline of manual exploration of
pictures is the development of inhibitory control. Throughout the first
years of life, children become increasingly capable of curbing impulses.
This general developmental change is supported by changes in the frontal
cortex. Increased inhibitory control presumably helps infants restrain their
impulse to interact directly with pictures, setting the stage for them to
simply look, as adults do.
Experience with pictures must play a role in this development as well. In an
image-rich society, most children encounter family photographs and picture
books on a daily basis. Such interactions teach children how pictures differ
from objects and how they are supposed to be targets of contemplation and
conversation, not action.
Nevertheless, it takes several years for the nature of pictures to be
completely understood. John H. Flavell of Stanford University and his
colleagues have found, for example, that until the age of four, many
children think that turning a picture of a bowl of popcorn upside down will
result in the depicted popcorn falling out of the bowl.
Pictures are not the only source of symbol confusion for very young
children. For many years, my colleagues and students and I watched toddlers
come into the lab and try to sit down on the tiny chair from the scale
model--much to the astonishment of all present. At home, Uttal and Rosengren
had also observed their own daughters trying to lie down in a doll's bed or
get into a miniature toy car. Intrigued by these remarkable behaviors that
were not mentioned in any of the scientific literature we examined, we
decided to study them.
Gulliver's Errors
We brought 18- to 30-month-old children into a room that contained, among
other things, three large play objects: an indoor slide, a child-size chair
and a car toddlers could get inside and propel around the room with their
feet. After a child had played with each of the objects at least twice, he
or she was escorted from the room. We then replaced the large items with
identical miniature versions. When the child returned, we did not comment on
the switch and let him or her play spontaneously. If the toddler ignored the
miniature toys for more than three or four minutes, however, we would draw
attention to them.
We then examined films of the children's behavior for what we came to call
scale errors: earnest attempts to perform actions that are clearly
impossible because of extreme differences in the relative size of the
child's body and the target object. We were very conservative in what we
counted as a scale error.
Almost half the children committed one or more of these mistakes. They
attempted with apparent seriousness to perform the same actions with the
miniature items that they had with the large ones. Some sat down on the
little chair: they walked up to it, turned around, bent their knees and
lowered themselves onto it. Some simply perched on top, others sat down so
hard that the chair skittered out from under them. Some children sat on the
miniature slide and tried to ride down it, usually falling off in the
process; others attempted to climb the steps, causing the slide to tip over.
(With the chair and slide made of sturdy plastic and only about five inches
tall, the toddlers faced no danger of hurting themselves.) A few kids tried
to get into the tiny car. Just as they had done with the large version, they
opened the door and attempted--often with remarkable persistence--to force a
foot inside. One little girl went so far as to take off her shoe in the
apparent hope that her foot would then fit!
Interestingly, most of the children showed little or no reaction to their
failed attempts with the miniatures. A couple seemed a bit angry, a few
looked sheepish, but most simply went on to do something else. We think the
lack of reaction probably reflects the fact that toddlers' daily lives are
full of unsuccessful attempts to do one thing or another.
Our interpretation is that scale errors originate in a dissociation between
the use of visual information for planning an action and for controlling its
execution. When a child sees a miniature of a familiar object, visual
information--the object's shape, color, texture and so on--activates the
child's mental representation of its referent. Associated with that memory
is the motor program for interacting with the large object and other similar
objects. In half the children we studied, this motor program was presumably
activated but then inhibited, and the children did not attempt to interact
with the miniature in the same way as they did with the large version.
But in the other half the motor routine was not inhibited. Once the child
began to carry out the typical motor sequence, visual information about the
actual size of the object was used to accurately perform the actions. Some
children, for instance, bent over the tiny chair and looked between their
legs to precisely locate it; those trying to get into the miniature car
first opened its door and then tried to shove their foot right in. In
deciding to interact with the replica, the children relied on visual
information linking it to the normal-size object, but in executing their
plan, they used visual information about the miniature's actual size to
guide their actions. This dissociation in the use of visual information is
consistent with influential theories of visual processing--ones positing
that different regions of the brain handle object recognition and planning
versus the execution and control of actions.
Scale errors involve a failure of dual representation: children cannot
maintain the distinction between a symbol and its referent. We know this
because the confusion between referent and symbolic object does not happen
when the demand for dual representation is eliminated--a discovery I made in
1997 when Rosengren and Kevin F. Miller of the University of Illinois and I
convinced two-and-a-half-year-olds--with the full consent of their parents,
of course--that we had a device that could miniaturize everyday objects.
The Magical Machine
Using our amazing shrinking machine, we hoped to see if the need to think of
an object in two ways at once was at the heart of young children's inability
to appreciate symbols. If a child believes that a machine has shrunk an
object or a room, then in the child's mind the miniature is the thing
itself. There is no symbolic relation between room and model, so children
should be able to apply what they know about the big version to the little
one.
We used the powers of our device to turn toys into miniature versions of
themselves and to shrink a large tent. In front of the child, we placed a
toy--a troll doll with vivid purple hair--in a tent and aimed the shrinking
machine at the tent. The child and experimenter then decamped to another
room to wait while the machine did its work. When they returned to the lab,
a small tent sat where the big one had been. (One of the remarkable things
about this study is the fact that the children did not find it at all
surprising that a machine could miniaturize objects. Or that it might need
privacy to do so.)
When we asked the children to search for the toy, they immediately looked in
the small tent. Believing the miniature to actually be the original tent
after shrinking, they successfully retrieved the hidden toy. Unlike in our
scale model experiment, they had no dual representation to master: the small
tent was the same as the large tent, and thus the toy was where it should
be, according to the toddlers' view of the world.
Understanding the role of dual representation in how young children use
symbols has important practical applications. One has to do with the
practice of using dolls to interview young children in cases of suspected
sexual abuse. The victims of abuse are often very young children, who are
quite difficult to interview. Consequently, many professionals--including
police officers, social workers and mental health professionals--employ
anatomically detailed dolls, assuming that a young child will have an easier
time describing what happened using a doll. Notice that this assumption
entails the further assumption that a young child will be able to think of
this object as both a doll and a representation of himself or herself.
These assumptions have been called into question by Maggie Bruck of Johns
Hopkins University, Stephen J. Ceci of Cornell University, Peter A. Ornstein
of the University of North Carolina at Chapel Hill and their many
colleagues. In several independent studies, these investigators have asked
preschool children to report what they remember about a checkup with their
pediatrician, which either had or had not included a genital check.
Anatomically detailed dolls were sometimes used to question the children,
sometimes not. In general, the children's reports were more accurate when
they were questioned without a doll, and they were more likely to falsely
report genital touching when a doll was used.
Based on my research documenting young children's difficulty interpreting
symbolic objects, I suspected that very young children might not be able to
relate their own body to a doll. In a series of studies in my lab using an
extremely simple mapping task, Catherine Smith placed a sticker somewhere on
a child--on a shoulder or foot, for example--and asked the child to place a
smaller version of the sticker in the same place on a doll. Children between
three and three-and-a-half usually placed the sticker correctly, but
children younger than three were correct less than half the time. The fact
that these very young children cannot relate their own body to the doll's in
this extremely simple situation with no memory demands and no emotional
involvement supports the general case against the use of anatomically
detailed dolls in forensic situations with young children. (Because of many
demonstrations akin to this one, the use of dolls with children younger than
five is viewed less favorably than in the past and has been outlawed in at
least one state.)
Educational Ramifications
The concept of dual representation has implications for educational
practices as well. Teachers in preschool and elementary school classrooms
around the world use "manipulatives"--blocks, rods and other objects
designed to represent numerical quantity. The idea is that these concrete
objects help children appreciate abstract mathematical principles. But if
children do not understand the relation between the objects and what they
represent, the use of manipulatives could be counterproductive. And some
research does suggest that children often have problems understanding and
using manipulatives.
Meredith Amaya of Northwestern University, Uttal and I are now testing the
effect of experience with symbolic objects on young children's learning
about letters and numbers. Using blocks designed to help teach math to young
children, we taught six- and seven-year-olds to do subtraction problems that
require borrowing (a form of problem that often gives young children
difficulty). We taught a comparison group to do the same but using pencil
and paper. Both groups learned to solve the problems equally well--but the
group using the blocks took three times as long to do so. A girl who used
the blocks offered us some advice after the study: "Have you ever thought of
teaching kids to do these with paper and pencil? It's a lot easier."
Dual representation also comes into play in many books for young children. A
very popular style of book contains a variety of manipulative features
designed to encourage children to interact directly with the book
itself--flaps that can be lifted to reveal pictures, levers that can be
pulled to animate images, and so forth.
Graduate student Cynthia Chiong and I reasoned that these manipulative
features might distract children from information presented in the book.
Accordingly, we recently used different types of books to teach letters to
30-month-old children. One was a simple, old-fashioned alphabet book, with
each letter clearly printed in simple black type accompanied by an
appropriate picture--the traditional "A is for apple, B is for boy" type of
book. Another book had a variety of manipulative features. The children who
had been taught with the plain book subsequently recognized more letters
than did those taught with the more complicated book. Presumably, the
children could more readily focus their attention with the plain 2-D book,
whereas with the other one their attention was drawn to the 3-D activities.
Less may be more when it comes to educational books for young children.
As these various studies show, infants and young children are confused by
many aspects of symbols that seem intuitively obvious to adults. They have
to overcome hurdles on the way to achieving a mature conception of what
symbols represent, and today many must master an ever expanding variety of
symbols. Perhaps a deeper understanding of the various stages of becoming
symbol-minded will enable researchers to identify and address learning
problems that might stem from difficulty grasping the meanings of symbols.
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