Adult age differences in self-ordered pointing task performance: Contributions from working memory, executive function and speed of information processing

This study investigated adult age differences in, and predictors of, the performance of a test of executive function, the Self-Ordered Pointing Task (SOPT; Petrides & Milner, 1982). Performance on the SOPT is thought to rely on high level working memory processes, therefore, measures reflecting the common operationalization of working memory, along with measures of executive function and speed of information processing, were investigated as predictors of SOPT performance. Younger (aged 17-48 years) and older (aged 65-88 years) adults completed a 16-item, 3-trial, modified version of Shimamura and Jurica's (1994) version of the SOPT, and tests assessing working memory, executive function and speed. Results showed that younger adults made fewer errors on the SOPT. There was no age difference in the frequency of use of a clustering strategy. Contrary to expectations, working memory was not a good predictor of individual or age differences in SOPT performance. Instead, speed of processing, and to a lesser extent, measures of perseverations, made larger unique and overlapping contributions to the variance. The SOPT and its association, or dissociation, with other measures of working memory may be useful for research into the nature of working memory and executive function and the theoretical links between them.