Age-related Declines in Prospective Memory: Modulation of the Prospective and Retrospective Components

Young (ages 18-22 years) and older (ages 61-87 years) adults (N = 106) played the Virtual Week board game, which involves simulating common prospective memory (PM) tasks of everyday life (e.g., taking medication), and performed working memory (WM) and vigilance tasks. The Virtual Week game includes regular (repeated) and irregular (nonrepeated) PM tasks with cues that are either more or less focal to other ongoing activities. Age differences in PM were reduced for repeated tasks, and performance improved over the course of the week, suggesting retrieval was more spontaneous or habitual. Correlations with WM within each age group were reduced for PM tasks that had more regular or focal cues. WM (but not vigilance) ability was a strong predictor of irregular PM tasks with less focal cues. Taken together, these results support the hypothesis that habitual and focally cued PM tasks are less demanding of attentional resources (specifically, WM), whereas tasks that are more demanding of controlled attentional processes produce larger age differences, which may be attributable to individual differences in WM.

The age benefit found in many naturalistic prospective memory (PM) tasks has been taken as evidence that PM performance in real life may be spared from aging. However, this conclusion lacks empirical confirmation. Hence, the aim of the present study was to examine possible age differences in the content of everyday PM intentions and their performance. Everyday PM was assessed in young and older adults using a diary approach. Results confirmed a general age benefit for real-life PM tasks. Importantly, this finding was qualified by revealing that the benefit only held true for specific types of intentions such as health and social intentions. Further, moderation analyses showed that the relationships between cognitive functioning and everyday PM were different for young and older adults. While better inhibition, short-term and long-term memory were related with successful PM performance in the young, this was not the case in the older adults. The present findings suggest that the age benefit found in naturalistic experimenter-given tasks extends to real-life PM performance, but may differ depending on the type of intention. Furthermore, cognitive functioning predicts performance in the young, but not in the older adults.

To explain age deficits found in laboratory-based prospective memory (PM) tasks, it has recently been suggested that the testing situation per se may be more stressful for older adults, thereby impairing their performance. To test this assumption, subjective and physiological stress levels were assessed at several times during the experiment in 33 younger and 29 older adults. In addition, half of participants were randomized in a condition where they completed a relaxation intervention before performing a time-based PM task. Results confirmed the age deficit in laboratory PM. Subjective and physiological stress levels showed no age difference and no detrimental association with PM. The intervention successfully reduced stress levels in both age groups but had no effect on PM or the age deficit. In conclusion, data suggest that age deficits usually observed in laboratory PM may not be due to higher stress levels in the older adults.

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.

ABSTRACTAccording to the executive framework of prospective memory (PM), age-related differences in PM performance are mediated by age-related differences in executive functioning (EF). The present study further explored this framework by examining which specific components of EF are associated with PM differences between and within three age groups. A group of children (7–9 years; N = 108), adolescents (12–14 years; N = 112), and adults (17–23 years; N = 106) performed focal- and non-focal event-based PM (EBPM) tasks, a time-based PM (TBPM) task, and tasks measuring EF components. Differences between age groups in focal EBPM, non-focal EBPM, and TBPM performance were mediated by, respectively, differences in interference control and response inhibition, performance on the ongoing task, and differences in working memory and response inhibition. However, within-age group analyses only revealed WM updating as significant predictor of TBPM performance in the adolescent group. These results support and further qualify the executive framework of PM. The differences in outcome dependent on the examined age range might be important for explaining mixed results of previous studies regarding the precise EF components underlying age-related PM task performance differences.

The current study examined the effects of stereotype threat on prospective memory (PM) performance in younger versus older adults by using a focal (i.e., low cognitive demands) and a nonfocal (i.e., high cognitive demands) PM task. Sixty younger and 60 older adults performed an event-based PM task, in which task instructions were experimentally manipulated. Half of the participants received instructions that emphasized the memory component of the task (memory condition; i.e., high stereotype threat for older adults) whereas the other half was instructed that the task evaluated participants' reading-ability (reading condition; i.e., low stereotype threat). Older adults' PM performance was worse than younger adults' only in the memory condition and these effects were specific for nonfocal PM cues as well as for old-old adults. Conceptually, this indicates that stereotype threat particularly impacts age effects for cognitive processes associated with executive control and that this particularly affects old-old adults. Therefore, the current findings illustrate for the first time that age differences in PM can be influenced by stereotype threat and suggest changes in controlled attention as possible cognitive pathway.

Cognitive aging researchers have long reported “paradoxical” age differences in prospective memory (PM), with age deficits in laboratory settings and age benefits (or no deficits) in real-world settings. We propose a theoretical account that explains this “age-PM-paradox” as a consequence of both methodological factors and developmental changes in cognitive abilities and personality traits. To test this account, young and older adults performed a series of naturalistic PM tasks in the lab and real world. Age-related PM deficits were observed in both lab-based tasks where demands were implemented using virtual reality and in-person role-playing. In contrast, older adults performed equal to or better than young adults on both real-world tasks, where demands were implemented in participants’ daily lives. Consistent with our proposed account, an index of these “paradoxical” effects was partially predicted by age-related differences in working memory, vigilance, agreeableness, and neuroticism, whose predictive utility varied across task settings.

Age-related differences in prospective memory were examined in a laboratory-based task in which younger and older adults performed different actions whenever a semantically defined target word occurred in the context of a free-association task. Requirements for self-initiated retrieval operations were manipulated by presenting target words that were typical or atypical instances (e.g., milk vs ink) of a given semantic category (liquid). The results showed that age differences in prospective memory were accentuated when atypical items were used as targets, but reduced when highly typical targets were presented. Furthermore, age differences were not limited to remembering when to perform action, but young subjects also showed better performance in remembering what was to be done. These findings indicate that the magnitude of age difference in prospective memory interacts with task complexity, and support the view that prospective memory failures are accentuated in tasks with high resource demands on self-initiated retrieval operations.

This study examined time-based prospective memory performance in relation to age, monitoring strategy, response accuracy, and dual-task demands. Young, middle-aged and older adults (N = 115) completed a prospective memory task, in which they indicated the passing of time every 5 min while listening to a short story (low task demands) or completing a series of cognitive tasks (high task demands). Young and older adults showed similar patterns of monitoring behavior, with low rates of clock checking during the early phase of each 5-min interval, followed by linearly accelerating monitoring functions. However, to obtain the same level of prospective memory performance older adults needed more frequent clock checks than young adults. Furthermore, older adults' compensatory monitoring strategy was associated with an additional cost in primary task performance. Finally, increased primary task demands shifted age differences in prospective memory from monitoring frequency to response accuracy. These findings suggest that goal-directed behavior requires efficient task coordination and resource allocation, and that age-related differences in time-based prospective memory should be evaluated by using multiple outcome measures.

A feature of prospective memory tasks is that they tend to be embedded into other background activities. Two experiments examined how the demands of these background activities affect age differences in prospective memory. The first experiment showed that increasing the demands of the background activities (by adding a digit-monitoring task) significantly reduced prospective memory performance. Planned comparisons revealed that age differences in prospective memory were reliable only in the more demanding background condition. The second experiment revealed significant prospective memory declines when the demands were selectively increased at encoding for both younger and older adults. When the demands were selectively increased at retrieval, older adults were particularly affected. The authors propose a model that relies on both automatic retrieval processes and working memory resources to explain prospective memory remembering.

How executive functions are associated with event-based and time-based prospective memory during childhood

Cue saliency is known to influence prospective memory performance, whereby perceptually or conceptually distinct cues facilitate remembering and attenuate adult age-related deficits. The present study investigated whether similar benefits for older adults are also seen for emotional valence. A total of 41 older and 41 younger adults performed a prospective memory task in which the emotional valence of the prospective memory cues was manipulated. Emotionally valenced cues increased prospective memory performance across both groups. Age deficits were only observed when neutral (but not positive or negative) prospective cues were presented. Findings are consistent with predictions that salient cues facilitate participants' prospective memory performance and reduce age-related differences, while extending the concept of saliency to include emotional valence.

Depression has been found to be related to neurocognitive deficits in areas important to successful prospective memory (PM) performance, including executive function, attention, and retrospective memory. However, research specific to depression and PM has produced a mixed pattern of results. The current study further examined the task conditions in which event-based PM deficits may emerge in individuals with high depressive symptomatology (HDS) relative to individuals with low depressive symptomatology (LDS) and the capacity of HDS individuals to allocate attentional resources to event-based PM tasks. Sixty-four participants (32 HDS, 32 LDS) were required to make a PM response when target words were presented during an ongoing lexical decision task. When the importance of the ongoing task was emphasized, response time costs to the ongoing task, and PM accuracy, did not differ between the HDS and LDS groups. This finding is consistent with previous research demonstrating that event-based PM task accuracy is not always impaired by depression, even when the PM task is resource demanding. When the importance of the PM task was emphasized, costs to the ongoing task further increased for both groups, indicating an increased allocation of attentional resources to the PM task. Crucially, while a corresponding improvement in PM accuracy was observed in the LDS group when the importance of the PM task was emphasized, this was not true for the HDS group. The lack of improved PM accuracy in the HDS group compared with the LDS group despite evidence of increased cognitive resources allocated to PM tasks may have been due to inefficiency in the application of the allocated attention, a dimension likely related to executive function difficulties in depression. Qualitatively different resource allocation patterns may underlie PM monitoring in HDS versus LDS individuals.

The authors investigated the phenomenon that performance in an ongoing task declines when individuals must carry out a prospective memory (PM) task. This effect is referred to as the PM interference effect. The authors examined whether the PM interference effect differs between event-based and time-based PM tasks and whether it is increased among the elderly. The authors also investigated adult age differences in PM performance and the potential underlying mechanisms of the age deficits in PM. They found that the PM interference effect was greater in event-based than in time-based tasks. However, aging was not associated with an increase in PM interference effects. Age differences in PM performance were more exaggerated in time-based than event-based PM, but they were not mediated by age differences in traditional cognitive ability measures. In time-based PM, age showed a unique adverse effect even after controlling for the ability to externally monitor the time, leading to the possibility that aging disrupts time-based PM because of deficits in internally processing the time.

Two experiments investigated the effects of normal aging and dementia on laboratory-based prospective memory (PM) tasks. Participants viewed a film for a later recognition memory task. In Experiment 1, they were also required either to say "animal" when an animal appeared in the film (event-based PM task) or to stop a clock every 3 min (time-based PM task). In both tasks, young participants were more successful than older participants, who were, in turn, more successful than patients with Alzheimer's disease (AD). For successful remembering in the time-based task, older participants and AD patients checked the clock more often than did young participants. In Experiment 2, participants were asked to reset a clock either when an animal appeared in the film (unrelated cue-action) or when a clock appeared in the film (related cue-action). Responses were faster in the related condition than in the unrelated condition. Again, there were differences in PM performance between young and older participants, and between older participants and AD patients. The observed deficits were not due to the forgetting of the PM task instructions in either experiment. Retrospective memory (RM) tasks (digit span, sentence span, free recall, and recognition) were more impaired by AD than were the PM tasks. Factor analysis revealed separate factors corresponding to RM and PM.