[Paleopsych] Scientific American: Mindful of Symbols (fwd)
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Subject: Scientific American: Mindful of Symbols
Mindful of Symbols
July 25, 2005
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
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
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.
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.)
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
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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