The long-term objectives are to identify micro-level cognitive processes and macro-level cultural mechanisms that support the development of high-level skill in problem solving across the life-span. A major focus is on the compensatory mechanisms that older adults may use to allow them to maintain high performance levels on difficult problem-solving tasks despite age-related declines in information processing efficiency. Understanding compensatory processes may be instrumental in helping aging adults to cope intelligently with negative changes in physical and mental health, as well as to help maintain the productivity of our aging labor force. We will focus on expert problem solving in chess, because chess problem solving relies on basic perceptual, attentional, memory, and search processes,enabling it to serve as a model task environment for exploring age trends in cognition in general, and expert problem solving in particular. Further, public records of chess ratings enable population-level analyses of life-span and cultural patterns. The following questions form the core concerns of this project: How do chess players acquire and maintain skill in chess across the life-span? What types of study and practice patterns do they use? What role do cultural and social factors associated with age, nationality, and gender play in acquiring skill? Can older players compensate for reduced processing efficiency by drawing on acquired knowledge? What types of knowledge support chess expertise? How does the search process, the core component of problem solving in chess, vary with age, skill, and problem difficulty? We will examine longitudinal chess performance via chess rating lists from the USA and from the World Chess Federation (FIDE). A subset of these players in Germany, Russia, Canada, and the USA will be contracted to participate in the following projects: A) Interviews to gather practicing behavior data, shown to be one of the primary determinants of skill acquisition and maintenance. We will probe social and cultural supports for acquiring and maintaining skill. Follow-up studies will examine practice on-line for a subset of players. B) Chess and non-chess control experiments that will probe the perceptual and cognitive components of skill. Eye-movement studies will trace perceptual matching processes. Time-accuracy functions and think aloud procedures will probe memory and problem solving processes. We will model age and skill effects using EPAM-like computer simulations that vary speed and working memory capacity.