Effects of task types and time interval conditions on age-related decline in verbal working memory.

Age-related differences in working memory (WM) components were investigated by manipulating the time interval and interference effects between phonological and semantic judgment tasks to identify tasks to best discriminate between younger and older groups. The 96 participants (young = 48; old = 48) prospectively performed two task types of WM, with phonological and semantic judgment tasks, which were administered while varying the three interval conditions: 1-s unfilled (UF), 5-s UF, and 5-s filled (F). The main effect for age was significant in the semantic judgment task but not in the phonological judgment task. The main effect for the interval conditions were significant in both tasks. A 5-s UF condition applied to a semantic judgment task could significantly differentiate the older group from the younger group. Differential effects of time interval manipulation in semantic and phonological processing are involved in WM resources. The older group could be differentiated by varying the task types and interval conditions, indicating that the semantic-related WM burdens may contribute to a superior differential diagnosis of aging-related WM decline.