Since most working memory (WM) tasks used in dual-task (DT) postural paradigms include both storage and processing of information, it is difficult to determine the extent to which each of these contributes to interference with balance control. In the current study, a change-detection task (changes in colored squares between two presentation events) that estimates visual working memory capacity (VWMC) was paired with tasks of increasing postural demand (stance, perturbation) in young adults (YAs) and older adults (OAs) and performance compared between the two postural conditions and across the two populations. The change-detection task was selected as it requires storage of information without updating or manipulation; 34 YAs, 34 OAs, and five frail OAs were recruited. A significant reduction in VWMC occurred with increasing postural demand during the perturbation condition for both YAs (p < 0.01) and OAs (p < 0.001). VWMC was also significantly lower for OAs than YAs in the control condition (1.8 ± 0.7 vs. 2.8 ± 0.6) (p < 0.001). OAs showed a significant increase in the number of trials in which steps or rise to toes occurred during recovery between single-task (ST) and DT (p < 0.05; p < 0.05). OAs also showed a significant increase in normalized tibialis anterior amplitude (p < 0.001) following perturbations. YAs showed an increase in normalized area under the center of pressure trajectory and in AP forces (nAcopx1: p < 0.001; nFap1: p < 0.05) during the DT condition.