| Abstract: | These experiments evaluated two potential sources of developmental changes in pattern encoding: advances at a perceptual level enabling better representation of the spatial relations among elements, and acquisition of metaperceptual knowledge supporting a deliberate search for distinguishing features. Children 6, 10, and 12 years old, as well as adults encoded high level distortions of random dot configurations. These materials were originally used by Posner and Keele (1968). In the first experiment, subjects matched exemplars to their prototypes. In two other experiments, subjects learned to categorize distortions under two different training conditions—one designed to focus attention on individual exemplars, the other designed to facilitate comparison of exemplars within and across categories. Following training, subjects classified new instances into the learned categories. The same pattern of developmental change was found in the matching task and in the classification task: major gains between ages 6 and 12 and continued gains to adulthood. Several aspects of the results identify change at a perceptual level after age 10 as a source of this development, independent of possible contributions from metaperceptual advances. |
