Dual representation and young children's use of scale models.

To use a symbolic object such as a model, map, or picture, one must achieve dual representation; that is, one must mentally represent both the symbol itself and its relation to its referent. The studies reported here confirm predictions derived from this concept. As hypothesized, dual representation was as difficult for 2 1/2-year-olds to achieve with a set of individual objects as it was with an integrated model. Decreasing the physical salience of a scale model (by placing it behind a window) made it easier for 2 1/2-year-old children to treat it as a representation of something other than itself. Conversely, increasing the model's salience as an object (by allowing 3-year-old children to manipulate it) made it more difficult to appreciate its symbolic import. The results provide strong support for dual representation.