Metacognition has been the subject of intense scientific inquiry within the cognitive aging literature, yet despite its centrality in contemporary research, two questions remain unanswered. First, how can researchers appropriately gauge people’s holistic views of their cognitive abilities—or global metacognitive beliefs—and assess the objective accuracy of those subjective beliefs? Two, to what extent do factors such as age and cognitive task experience influence people’s global metacognitive beliefs? The present study sought to address these questions. Here, two novel measures—a computerized cognitive test battery and global metacognitive beliefs questionnaire—were implemented to track the congruency between participants’ global subjective metacognitive beliefs and global objective cognitive ability. Previous research has shown that prior task experience can impact local (i.e., task-based) metacognitive beliefs. Building on this finding, the current research examined whether younger and older adults’ global metacognitive beliefs would change in response to taking a cognitive test battery (as compared to merely the practice trials of said battery), and if so, whether this task-induced belief update would persist after a one-week delay. Compared to younger adults, older adults’ global metacognitive accuracy increased with time, although it is unclear from the present results whether this enhancement to metacognitive accuracy was dependent on the type of cognitive task older adults took. Additional studies are needed to determine when, if ever, task experience truly does impact younger and older adults’ global metacognition.