Judy DeLoache describes her research into the difficulties children experience with symbols
A. 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 in my laboratory. The real space contained basic furniture such as a couch and table. The miniature version was as similar as possible to its larger counterpart: the furniture was the same shape and material and was arranged in the same position. For the study, a child watched as we hid a miniature toy - a plastic dog we called Little Snoopy in the model. We then encouraged the child to find 'Big Snoopy', a large version of the toy 'hiding in the same place in his big room.'
B. The three-year-olds were 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 failed abysmally. They cheerfully ran into the room to retrieve the large toy, but most 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.
C. Their failure to use what they knew about the model to draw an inference about the real room indicated that they did not appreciate the relation between the model and the room. I realised my memory study was instead a study of symbolic understanding and that the children's failure might be telling us something about how and when children acquire the ability to understand that one object stands for another.
D. The first type of symbolic object that infants and young children master is the picture. No symbols seem simpler to adults, but infants initially find pictures perplexing. The problem stems from the duality inherent in all symbolic objects: they are real in themselves and also representations of something else. A few years ago I became intrigued by anecdotes suggesting that infants do not appreciate this duality-stories of a baby trying to pick up a depicted toy or fit a foot into a photograph of a shoe. We assumed such behaviour would be rare and therefore difficult to study.
E. Fortunately we were wrong. We began testing infants' understanding of pictures by putting a book of highly realistic colour photographs of individual objects in front of nine-month-olds. To our surprise, every child in the study reached out to feel or scratch the pictures. The confusion seems to be conceptual not perceptual. Infants can perfectly well perceive the difference between objects and pictures and given the choice they will choose the real thing. But they do not yet fully understand what pictures are and how they differ from real objects. However, when depicted objects bear little resemblance to the real thing as in a black and white drawing - infants rarely explore them. By 18 months, babies have come to appreciate that a picture merely represents an object; instead of manipulating the paper, they point to pictures and name objects. Nevertheless, it takes several years for the nature of pictures to be completely understood.
F. Studies have shown 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.
G. Pictures are not the only source of confusion for very young children. In a third experiment, we brought a group of toddlers (18-to 30-month-old children) Into a room containing a child's slide, a chair, and a toddler-sized car. The children played with these for a while. Then we secretly replaced each object with an identical miniature version. Most children attempted to perform the same actions with the miniature items that they had with the larger ones. Some tried to sit on the chair, others attempted to climb into the car. Interestingly, most of the children showed little or no reaction to their failed attempts. We think this probably reflects the fact that toddlers' daily lives are full of unsuccessful attempts to do one thing or another.
H. This confusion has implications for educational practice. Teachers everywhere use blocks or other objects to represent numerical quantity. However, if young children do not understand the relation between an object and what it represents, this could be counterproductive. To demonstrate this, we taught six-and seven-year-olds a difficult subtraction problem using blocks. We taught an identical comparison group the same concept, but using pencil and paper. Both groups learned to solve the problems equally well, but the group using blocks took three times as long to do so.
I. Dual representation also comes into play in many children's books. Modern children's books are often 3D, with features that encourage children to interact directly with the book itself, for example flaps that can be lifted to reveal pictures. Graduate student Cynthia Chong and I reasoned that these features might distract children from the information. Accordingly, we used different types of books to teach letters to 30-month-old children. One was a simple old-fashioned alphabet book with each letter accompanied by an appropriate picture. The other was a 3-D version. The children using the traditional book subsequently recognised more letters than those using the 3-D book.
J. Presumably, the children could concentrate more easily with the plain 2-D book, whereas with the other one they were distracted by the 3-D activities. Less may be more when it comes to educational books for young children.