The contribution of impaired working memory monitoring to performance of the self-ordered pointing task in normal aging and Parkinson's disease

The factors contributing to the working memory deficit observed in older 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 size. This pattern was proposed to result from a monitoring deficit where individuals failed to maintain an integrated representation of how far they had proceeded in the trial, an interpretation consistent with animal work by M. Petrides (1995).