The project is concerned with developmental differences in perceptual analysis of dimensions and selective attention and the contribution of these processes to learning and memory tasks. In order to assess the development of these processes, scaling procedures, classification tasks, speeded sorting tasks, reaction time tasks, and short-term memory tasks are employed. Our objective is to discover the properties of these processes at different developmental levels, how the processes change with progression in development, and the degree to which the processes can be modified by different task variables at different ages.