This protocol will attempt to determine the topographical distribution in the brain of the cognitive components of planning using the [150] water PET blood flow technique. We will administer perception, motor, simple decision, and planning tasks using the game of chess and the Tower of Hanoi Test as paradigms. Utilizing a "subtraction technique" we hope to identify those areas of cerebral cortex which are most activated by planning processes. It is predicted that the dorsolateral frontal areas will be most prominently activated. It is also predicted that the essential components of the planning process will be the same regardless of the type of plans being executed. The data we collect will be of value in determining 1) the neural representation of planning processes and 2) in guiding cognitive models of the planning system.