SIMPLE AND COMPLEX MENTAL SUBTRACTION - STRATEGY CHOICE AND SPEED-OF-PROCESSING DIFFERENCES IN YOUNGER AND OLDER ADULTS

Thirty-six younger adults (10 male, 26 female; ages 18 to 38 years) an d 36 older adults (14 male, 22 female; ages 61 to 80 years) completed simple and complex paper-and-pencil subtraction tests and solved a ser ies of simple and complex computer-presented subtraction problems. For the computer task, strategies and solution times were recorded on a t rial-by-trial basis. Older Ss used a developmentally more mature mix o f problem-solving strategies to solve both simple and complex subtract ion problems. Analyses of component scores derived from the solution t imes suggest that the older Ss are slower at number encoding and numbe r production but faster at executing the borrow procedure. In contrast , groups did not appear to differ in the speed of subtraction fact ret rieval. Results from a computational simulation are consistent with th e interpretation that older adults' advantage for strategy choices and for the speed of executing the borrow procedure might result from mor e practice solving subtraction problems.