THE CONTRIBUTION OF IMPAIRED WORKING-MEMORY MONITORING TO PERFORMANCEOF THE SELF-ORDERED POINTING TASK IN NORMAL AGING AND PARKINSONS-DISEASE

The factors contributing to the working memory deficit observed in old er adults and individuals with Parkinson's disease on the Self-Ordered Pointing Task were examined in 2 experiments. A detailed analysis of the error data revealed that errors tended to be clustered toward the end of a trial and that this effect was somewhat independent of set si ze. This pattern was proposed to result from a monitoring deficit wher e individuals failed to maintain an integrated representation of how f ar they had proceeded in the trial, an interpretation consistent with animal work by M. Petrides (1995).