Aging, expertise and fine motor movement.

Age-graded decrements in accuracies and maximum speed of fine motor movements observed in numerous experimental studies have nurtured general factor explanations like the assumption of general age-related slowing of central cognitive processes. This review focuses on two domains of investigation that yielded challenges to general factor models. First, experimental approaches aiming at the decomposition of fine motor skills provide evidence for the dissociability of timing, sequencing, and executive control components that show differential rather than general age-related changes. Second, studies on cognitive-motor expertise demonstrate that age-related changes in critical skill components depend on individuals' time investments into specific practice activities. It is argued that the process dissociations observed at the behavioral level in developmental (i.e. age and expertise) studies reflect individuals' long-term adaptations to internal and external performance constraints. The outcomes of these adaptation processes are stable interindividual differences in component processes.