Age differences in prospective memory: Laboratory versus naturalistic settings

Prospective memory (PM) is the ability to remember and perform intended actions at the appropriate point in the future. PM is a cognitive ability that is vital to many aspects of daily functioning, and it is particularly important for older adults who wish to maintain functional independence. The overall aim of this thesis was to investigate factors that potentially contribute to the age-PM paradox. The age-PM paradox refers to the contrasting age effects on PM performance with age-related deficits observed on laboratory tasks, but no age differences or even age-related benefits observed on naturalistic tasks. Several proposed factors that possibly contribute to the age-PM paradox were examined in two tangential studies. Firstly, a descriptive study of self-directed PM tasks in daily life was conducted. The study examined how the context of PM task completion in the real world might vary between young and older adults, as such differences may contribute to age differences in naturalistic PM performance. To improve upon previous naturalistic studies, the study employed an experience-sampling method to capture PM successes and failures throughout the day. Contrary to popular belief, the findings suggest that dissimilarities in the demands of everyday life and the usage of external reminders, such as diaries, cannot explain the improved naturalistic PM performance of older adults. However, older adults were found to regard their PM tasks as important more often than young adults. Older adults also rehearsed their PM intentions more frequently than young adults. Thus, it is possible that the age benefit observed in naturalistic settings is related to older adults’ motivation and their ability to plan and rehearse their PM tasks within their own environment. Relatively few instances of PM failures were reported by both age groups. Further evidence suggests that participants retrieved their PM intentions through both spontaneous retrieval and strategic monitoring processes, which provides support for the multiprocess framework of PM. The second study rigorously examined whether the comparison of inherently dissimilar tasks could be contributing to the age-PM paradox. Laboratory PM tasks are predominantly event-based tasks, while naturalistic PM tasks are typically time-based, occurring at a set time of day. To address the lack of task comparability across settings, novel naturalistic PM measures were developed to objectively assess PM performance on three types of tasks: event-based, scheduled time-based (typical of prior naturalistic studies), and time-check tasks (typical of prior laboratory studies). The study is the first investigation of age differences in laboratory and naturalistic settings on all three types of PM tasks using the same participant sample in both settings. Laboratory PM performance was assessed using a computerised version of Virtual Week, which simulates activities of daily life in a board game format. Naturalistic PM performance was assessed using smartphones and an application developed specifically for this thesis. In the laboratory, age-related deficits were observed on all three task types. However, in the naturalistic setting, older adults performed better than young adults on scheduled time-based tasks, performed just as well as the young adults on event-based tasks, and performed equally poorly on time-check tasks. The findings suggest that older adults demonstrate improved PM performance in everyday life when the PM tasks possess an event-like quality, which allows for further environmental support for successful task completion. Regardless of the setting, older adults consistently exhibited poor performance on time-check tasks. This finding suggests that older adults’ PM performance suffers when the PM tasks are particularly demanding and rely heavily on effortful monitoring processes for intention retrieval. Overall, the current research suggests that the age-PM paradox cannot be completely explained by contextual differences surrounding naturalistic PM performance or by the lack of task comparability across settings in the existing literature. However, given the substantial improvement in older adults’ naturalistic performance on scheduled time-based tasks, but not on time-check tasks, this thesis highlights the importance of this relatively rare time-based task distinction when considering the age-PM paradox. Taken together, the studies indicate that older adults’ naturalistic PM performance benefits from explicit cues, environmental support, and the ability to plan and rehearse PM intentions.