The goal of this project is to determine the influence of age-related change in mental information processing speed on cognitive development, specifically developmental change in memory, reasoning, and academic skills. The subjects in the research will be 5- to 20-year-olds. In each of six experiments we will measure three types of construct: global speed of processing, criterion performance (e.g., memory, analogical reasoning), and specific constructs hypothesized to link processing speed to the criterion measure. The causal links between these construct types will be evaluated using path analysis and structural equation modeling. Results from this project should shed light on how age-related change in processing speed contributes to age-related change in memory, reasoning, and academic skills. Specifically, although age-related change in speed of processing may be particularly salient in performance on speeded tasks, its influence may be much more widespread, affecting performance whenever a number of activities must be completed in a fixed period of time. In these situations, poor performance may result because processing speed was too slow for the processes necessary for task performance to be completed in the time allotted. For example, speed of processing may explain why, relative to adolescents and young adults, children can rehearse less information per unit of time and, consequently, remember less accurately. The planned experimentation will help determine the extent to which age- related change in processing speed is in fact a causal force in the development of memory, reasoning, and academic skills.
