Working memory in event‐ and time‐based prospective memory tasks: Effects of secondary demand and age

Aging and time-based prospective memory in the laboratory: a meta-analysis on age-related differences and possible explanatory factors

In older adults' everyday life, time-based prospective memory (TBPM) is relevant as health-related intentions are often part of daily activities. Nonetheless, it is still unclear which task-related factors can potentially moderate the magnitude of age-related differences, such as duration of the PM target time (the time-window within which an individual must complete a given TBPM task), the frequency of the TBPM tasks, and the criterion chosen to compute PM accuracy. The present meta-analysis aimed to quantify age-related differences in laboratory TBPM tasks, and to investigate how specific task-related factors potentially moderate the magnitude of age effects. The results showed that age effects consistently emerged among the studies, with older adults showing lower TBPM performance and checking the clock less often than younger adults, especially for shorter intervals (e.g., ≤ 4 min). Furthermore, the results indicated that the duration of the PM target time interacted with the frequency of the PM task, suggesting that learning effects may attenuate the magnitude of age differences in TBPM performance. The results are discussed in terms of potential implications about the possible cognitive processes involved in TBPM and aging, as well as in terms of robustness of the TBPM laboratory paradigm in aging research.

External Time Monitoring in Time-Based Prospective Memory: An Integrative Framework

We propose a new integrative framework of external time monitoring in prospective memory (PM) tasks and its relation with performance. Starting from existing empirical regularities and our theoretical analysis, the framework predicts that external monitoring in PM tasks comprises a first stage of loose monitoring to keep track of the passage of time, and a subsequent stage of finer-grained monitoring, based on interval reduction, to meet the PM deadline. Following our framework, we predicted and observed in three different datasets (N = 375): (1) a marked increase in external monitoring frequency in the final part of the period of the PM task, well captured by a proportional rate exponential growth function; (2) a positive association between individual compliance with this monitoring pattern and PM performance; (3) a positive relation between monitoring frequency in the time window immediately preceding the PM deadline and PM performance at the individual level; and (4) good individual compliance with an interval reduction pattern in external monitoring, especially in the time window closer to the PM deadline. These results support the proposed integrative framework, which has the potential to foster future research on external monitoring in PM and in other fields of cognitive science.

Comparing different tests to detect early manifestation of prospective memory decline in aging

Objective: Prospective memory (PM) is the ability to remember to perform future intentions. Previous studies have demonstrated that, compared to a younger cohort, healthy older adults have impairments in PM. Considering the importance of early detection of age-related PM decline, the present study aims to compare the performance of healthy older adults using three well-known PM tests commonly used in clinical settings.Method: In the present study, we tested 70 older adults (65-95 years old) using the Cambridge Prospective Memory Test (CAMPROMPT), the Memory for Intentions Screening Test (MIST) and the Royal Prince Alfred Prospective Memory Test (RPA-ProMem). In order to compare performance across tests and the interaction between age and cues, we performed a linear mixed model with random intercept and random slopes. Moreover, additional mixed models with random intercept were run for analyzing the additional information provided by MIST and RPA-ProMem regarding delay responses, response modality effects and type of errors committed.Results: Our data showed a drop in PM performance as age increased detected by all three tests. Furthermore, CAMPROMPT was the most sensitive test to identify differences in PM for event-and time-based cues, at least for participants with 65-77 years old. When data were analyzed in term of delay responses, participants were more accurate for 2 min delay (MIST) and 30 in delay (RPA-ProMem). Participants were less accurate when response modality was "verbal" compared to "action" (MIST) and made more PM errors as age increased.Conclusions: Overall, the study provides important information regarding age-related PM decline and can help researchers as well as clinicians in deciding the preferred test to evaluate PM performance.

Prospective memory and working memory in comparison. New experimental paradigms

Aim of the study: Prospective memory (PM) is a cognitive high load activity. Two main models showed the relation between working memory (WM) and PM. The preparatory attentional and memory processes model (PAM) posits an interdependence between WM and PM; while, the multiprocess framework assumes independence between these two functions.Materials and methods: With the aim to investigate this relation, two tasks were administered to a sample of 21 healthy participants. The first task (arithmetic) required low cognitive and WM load together with a prospective task, the second (PASAT) required high cognitive and WM load together with a prospective switching task. The prospective task included two modalities of administration: based on a sound cue (event-based) or at a given moment (time-based).Results: PM accuracy was influenced by WM only when paired to complex tasks that require high cognitive load on WM and active PM self-retrieval processes (time-PASAT).Conclusions: These results support partial independence between these two mechanisms.

An Effect of Chronic Stress on Prospective Memory via Alteration of Resting-State Hippocampal Subregion Functional Connectivity

The alteration of hippocampal function by chronic stress impairs higher order cognitive functions such as prospective memory (PM). However, how chronic stress affects hippocampal subregions related to PM remains largely unknown. In this study, the altered functional network of hippocampal subregions related to PM in chronic stress was explored. College students (N = 21) completed PM tasks and resting-state functional magnetic resonance imaging scans one month prior to (baseline) and during the final examination week (chronic stress). Hippocampal subregions’ seed-based functional connectivity (FC) and PM were compared between baseline and chronic stress. PM performance declined in chronic stress. The FC of the cornu ammonis 2, 3 and dentate gyrus (CA23DG) with the bilateral caudate and precuneus was increased in chronic stress, while the FC of the subicular complex (SUBC) with the left middle frontal gyrus, the left inferior parietal gyrus and the right supramarginal gyrus was decreased. There was a negative correlation between PM performance and the FC of hippocampal subregions. We found chronic stress impairs PM by decreasing the FC of SUBC and increasing the FC of CA23DG. These findings suggest functional changes in hippocampal subregion networks as a mechanism underlying the impairment of PM in chronic stress.

Time-Based Prospective Memory Is Associated with Functional Performance in Persons with MS

OBJECTIVE

Persons with multiple sclerosis (MS) often report prospective memory (PM) failures that directly impact their everyday life. However, it is not known whether PM deficits confer an increased risk of poorer everyday functioning. The aims of this study were to: (1) compare time- (Time-PM) and event-based PM (Event-PM) performance between persons with MS and healthy controls (HCs), (2) examine the neuropsychological correlates of PM in MS, and (3) examine the relationship between PM and everyday functioning in MS.

METHOD

A between-subjects design was used to examine 30 adults with MS and 30 community-dwelling HC. Participants were administered the Memory for Intentions Screening Test (MIST) to assess PM skills, the Actual Reality™ (AR) to assess everyday functioning, and a battery of cognitive tests.

RESULTS

The MS group performed significantly worse on Time-PM compared to HC but not on Event-PM tasks. While both Time-PM and Event-PM subscales were correlated with retrospective learning and memory, the MIST Time-PM subscale was correlated with executive functions. Significant correlations were observed between AR and the MIST Time-PM, but not Event-PM, subscales.

CONCLUSIONS

The results highlight the role of executive functions on Time-PM. Furthermore, significant relationships with AR extend the ecological validity of the MIST to MS populations.

The role of time-monitoring behaviour in time-based prospective memory performance in younger and older adults

Time-based prospective memory (TB-PM) is the ability to remember to perform an action at a specific moment in the future. Accurate TB-PM performance requires several cognitive processes that are known to decline in normal ageing. This study aimed to examine associations between TB-PM performance and executive functions and time perception in younger and older adults. TB-PM was assessed with the Virtual Week paradigm. Using a within-subjects experimental manipulation, participants performed TB-PM tasks both when a clock was in constant view and when it was hidden behind a button. Results showed that younger adults performed significantly better than older adults on all TB-PM task types, and checked the clock more often, and more strategically. Clock availability improved TB-PM performance in all participants. Correlational analyses showed that TB-PM accuracy was positively related to clock-checking frequency but unrelated to time perception. Relationships between executive functions and TB-PM differed across age groups as well as TB-PM task types. The findings suggest that different cognitive processes are required for different types of TB-PM tasks and in different ages. These results highlight the importance of considering TB-PM task parameters when investigating the role of cognitive processes in PM performance and their contribution to age-related PM decline.

Redefining the pattern of age-prospective memory-paradox: new insights on age effects in lab-based, naturalistic, and self-assigned tasks

Prospective memory (PM) involves remembering intended actions in the future, such as posting a letter when seeing a post box (event-based PM) or making a phone call at 2:00 pm (time-based PM). Studies on aging and PM have often reported negative age effects in the laboratory, but positive age effects in naturalistic tasks outside the laboratory (the so-called age–PM-paradox). The present study re-examined this pattern of the paradox by studying, for the first time, age differences in time- and event-based PM in lab-based, experimenter-generated naturalistic and self-assigned real-life PM tasks within the same sample of young and older adults. Results showed that differential age effects in and outside the laboratory were qualified by the type of PM cue. While age-related deficits were obtained for laboratory event-based tasks, no age effect was obtained for naturalistic event-based PM. Age benefits in the field were only observed for naturalistic time-based tasks, but not for participants’ own self-assigned time-based tasks. These findings indicate that the age benefits for naturalistic PM tasks may have been overestimated due to the dominant use of experimenter-generated naturalistic time-based PM tasks in previous studies. Therefore, the precise pattern of the age–PM-paradox may need redefining as mostly consisting of negative age effects in lab-based PM tasks and mostly the absence of negative age effects (rather than age benefits) in naturalistic and self-assigned tasks outside the laboratory.

Cognitive Strategies and Natural Environments Interact in Influencing Executive Function

Exposure to natural environments and the adoption of specific cognitive strategies are each claimed to have a direct influence on executive mental functioning. Here we manipulate both factors to help determine whether they draw on common cognitive resources. Three experiments investigated links between environmental effects (nature vs. urban video tours) and strategic effects (active vs. passive instructional approaches to the task). Each experiment used a pretest-posttest design and assessed executive mental functioning using a backward digit span task and Raven's progressive matrices. Experiment 1 manipulated participants' cognitive strategy through explicit instructions in order to establish a link between cognitive strategy and executive mental functioning. Experiment 2 used a pair of 10-min video tours (urban, nature) to examine the relationship between environmental exposure and executive mental function on the same tasks, replicating previous findings with the backward digit span task and extended them to a new task (i.e., Raven's progressive matrices). In Experiment 3, these two manipulations were combined to explore the relations between them. The results showed that the nature video tour attenuated the influence of task instructions relative to the urban video tour. An interaction between environmental video exposure and cognitive strategy was found, in that effects of cognitive strategy on executive function were smaller in the nature video condition than in the urban video condition. This suggests that brief exposure to nature had a direct positive influence on executive mental functioning.

Executive control and working memory are involved in sub-second repetitive motor timing

The nature of the relationship between timing and cognition remains poorly understood. Cognitive control is known to be involved in discrete timing tasks involving durations above 1 s, but has not yet been demonstrated for repetitive motor timing below 1 s. We examined the latter in two continuation tapping experiments, by varying the cognitive load in a concurrent task. In Experiment 1, participants repeated a fixed three finger sequence (low executive load) or a pseudorandom sequence (high load) with either 524-, 733-, 1024- or 1431-ms inter-onset intervals (IOIs). High load increased timing variability for 524 and 733-ms IOIs but not for the longer IOIs. Experiment 2 attempted to replicate this finding for a concurrent memory task. Participants retained three letters (low working memory load) or seven letters (high load) while producing intervals (524- and 733-ms IOIs) with a drum stick. High load increased timing variability for both IOIs. Taken together, the experiments demonstrate that cognitive control processes influence sub-second repetitive motor timing.

Loads and loads and loads: the influence of prospective load, retrospective load, and ongoing task load in prospective memory

In prospective memory tasks different kinds of load can occur. Adding a prospective memory task can impose a load on ongoing task performance. Adding ongoing task load (OTL) can affect prospective memory performance. The existence of multiple target events increases prospective load (PL) and adding complexity to the to-be-remembered action increases retrospective load (RL). In two experiments, we systematically examined the effects of these different types of load on prospective memory performance. Results showed an effect of PL on costs in the ongoing task for categorical targets (Experiment 2), but not for specific targets (Experiment 1). RL and OTL both affected remembering the retrospective component of the prospective memory task. We suggest that PL can enhance costs in the ongoing task due to additional monitoring requirements. RL and OTL seem to impact the division of resources between the ongoing task and retrieval of the retrospective component, which may affect disengagement from the ongoing task. In general, the results demonstrate that the different types of load affect prospective memory differentially.

How do we process event-based and time-based intentions in the brain? an fMRI study of prospective memory in healthy individuals

Prospective memory (PM) refers to the ability to remember to do something in the future, either in response to an event (event-based) or after a certain amount of time has elapsed (time-based). While the distinction between event- and time-based PM is widely acknowledged in the literature, little is known about the processes they share and those they do not. This is particularly true concerning their brain substrates, as almost all neuroimaging studies so far have focused on event-based PM. We proposed a functional magnetic resonance imaging paradigm assessing both event-based and time-based PM to 20 healthy young individuals. Analyses revealed that event- and time-based PM both induced activation in the posterior frontal and parietal cortices, and deactivation in the medial rostral prefrontal cortex. In addition, activation more specific to each condition, which may underlie differences in strategic monitoring, was highlighted. Thus, occipital areas were more activated during event-based PM, probably reflecting target-checking, while a network comprising the dorsolateral prefrontal cortex, the cuneus/precuneus and, to a lesser extent, the inferior parietal lobule, superior temporal gyrus, and the cerebellum, was more activated in time-based PM, which may reflect the involvement of time-estimation processes. These results confirm the allocation of attentional resources to the maintenance of intention for event-based and time-based PM, as well as the engagement of distinct mechanisms reflecting the monitoring strategies specific to each condition.

Prospective memory in HIV-associated neurocognitive disorders (HAND): the neuropsychological dynamics of time monitoring

Strategic monitoring during a delay interval is theorized to be an essential feature of time-based prospective memory (TB PM), the cognitive architecture of which is thought to rely heavily on frontostriatal systems and executive functions. This hypothesis was examined in 55 individuals with HIV-associated neurocognitive disorders (HAND) and 108 seronegative comparison participants who were administered the Memory for Intentions Screening Test (MIST), during which time-monitoring (clock-checking) behavior was measured. Results revealed a significant interaction between HAND group and the frequency of clock checking, in which individuals with HAND checked the clock significantly less often than the comparison group across the TB PM retention intervals of the MIST. Subsequent analyses in the HAND sample revealed that the frequency of clocking checking was positively related to overall TB performance, as well as to standard clinical measures of retrospective memory and verbal fluency. These findings add support to a growing body of research elucidating TB PM's reliance on strategic monitoring processes dependent upon intact frontostriatal systems. HIV-associated TB strategic time-monitoring deficits may manifest in poorer functioning outcomes, including medication nonadherence and dependence in activities of daily living. Future research is needed to further delineate the cognitive mechanisms underlying strategic time monitoring in order to advise rehabilitation strategies for reducing HAND-related TB PM deficits.

Traumatic Brain Injury and Prospective Memory in a Virtual Shopping Trip Task: Does It Matter Who Generates the Prospective Memory Target?

The current study aimed to investigate prospective memory in traumatic brain injury by using a laboratory-based but naturalistic style assessment task. The objective was to determine if performance differed when the prospective memory targets were self-generated or experimenter-generated (a generation effect). Sixteen people who had sustained a traumatic brain injury and had received rehabilitation were compared to 16 healthy age-matched control participants on a naturalistic virtual measure of shopping and prospective memory. Results demonstrated that the traumatic brain group was less accurate in overall prospective remembering performance than the control group but there was a lack of difference between the self- and experimenter-generated prospective memory targets for both participant groups. Both retrospective memory and executive attention of working memory were associated with prospective memory performance in the naturalistic task. The findings of the study suggest that the generation effect commonly observed in retrospective memory performance may not impact performance in prospective memory.

Distinct and shared cognitive functions mediate event- and time-based prospective memory impairment in normal ageing

Prospective memory (PM) is the ability to remember to perform an action at a specific point in the future. Regarded as multidimensional, PM involves several cognitive functions that are known to be impaired in normal ageing. In the present study we set out to investigate the cognitive correlates of PM impairment in normal ageing. Manipulating cognitive load, we assessed event- and time-based PM, as well as several cognitive functions, including executive functions, working memory, and retrospective episodic memory, in healthy participants covering the entire adulthood. We found that normal ageing was characterised by PM decline in all conditions and that event-based PM was more sensitive to the effects of ageing than time-based PM. Whatever the conditions, PM was linked to inhibition and processing speed. However, while event-based PM was mainly mediated by binding and retrospective memory processes, time-based PM was mainly related to inhibition. The only distinction between high- and low-load PM cognitive correlates lies in an additional, but marginal, correlation between updating and the high-load PM condition. The association of distinct cognitive functions, as well as shared mechanisms with event- and time-based PM, confirm that each type of PM relies on a different set of processes.

Transparent meta-analysis: does aging spare prospective memory with focal vs. non-focal cues?

Background

Prospective memory (ProM) is the ability to become aware of a previously-formed plan at the right time and place. For over twenty years, researchers have been debating whether prospective memory declines with aging or whether it is spared by aging and, most recently, whether aging spares prospective memory with focal vs. non-focal cues. Two recent meta-analyses examining these claims did not include all relevant studies and ignored prevalent ceiling effects, age confounds, and did not distinguish between prospective memory subdomains (e.g., ProM proper, vigilance, habitual ProM) (see Uttl, 2008, PLoS ONE). The present meta-analysis focuses on the following questions: Does prospective memory decline with aging? Does prospective memory with focal vs. non-focal cues decline with aging? Does the size of age-related declines with focal vs. non-focal cues vary across ProM subdomains? And are age-related declines in ProM smaller than age-related declines in retrospective memory?

Methods and Findings

A meta-analysis of event-cued ProM using data visualization and modeling, robust count methods, and conventional meta-analysis techniques revealed that first, the size of age-related declines in ProM with both focal and non-focal cues are large. Second, age-related declines in ProM with focal cues are larger in ProM proper and smaller in vigilance. Third, age-related declines in ProM proper with focal cues are as large as age-related declines in recall measures of retrospective memory.

Conclusions

The results are consistent with Craik's (1983) proposal that age-related declines on ProM tasks are generally large, support the distinction between ProM proper vs. vigilance, and directly contradict widespread claims that ProM, with or without focal cues, is spared by aging.

Positive effects of nicotine on cognition: the deployment of attention for prospective memory

RATIONALE

Human and animal studies over the last two decades report that nicotine can improve cognitive performance. Prospective memory (PM), the retrieval and implementation of a previously encoded intention, is also improved by pre-administration of nicotine. As with other nicotine effects, however, predicting precisely how and when nicotine improves the processes engaged by PM has proved less straightforward.

OBJECTIVE

We present two studies that explore the source of nicotine's enhancement of PM. Experiment 1 tests for effects of nicotine on preparatory attention (PA) for PM target detection. Experiment 2 asks whether nicotine enhances processing of the perceptual attributes of the PM targets.

MATERIALS AND METHODS

Young adult non-smokers matched on baseline performance measures received either 1 mg nicotine or matched placebo via nasal spray. Volunteers completed novel PM tasks at 15 min post-administration.

RESULTS

Experiment 1 confirmed that pre-administration of nicotine to non-smokers improved detection rate for prospective memory targets presented during an attention-demanding ongoing task. There was no relationship between PM performance and measures of preparatory attention. In experiment 2, salient targets were more likely to be detected than non-salient targets, but nicotine did not confer any additional advantage to salient targets.

CONCLUSION

The present study suggests that nicotinic stimulation does not work to enhance perceptual salience of target stimuli (experiment 2), nor does it work through better deployment of preparatory working attention (experiment 1). An alternative explanation that nicotine promotes PM detection by facilitating disengagement from the ongoing task is suggested as a future line of investigation.

Aging and prospective memory: the role of working memory and monitoring processes

BACKGROUND AND AIMS

Remembering to execute an earlier planned action is essential in everyday life, and is a prerequisite for independent living in old age. The purpose of the present study was to determine the influence of age in performing a prospective memory (PM) task and to analyze the differential contribution of working memory and attentional monitoring demands.

METHODS

In Experiment 1, a group of young and two groups of old adults were assigned to one of two low-demanding conditions: a picture-naming task (only-Naming) and a picture-naming plus a PM task (Naming+PM). In Experiment 2, a group of young and two groups of old adults performed one of two high-demanding conditions, in which working memory and attentional monitoring processes were examined, using a listening span-like task and a 1-back task within the PM paradigm of Experiment 1.

RESULTS

Prospective memory performance declined with age even in the low-demanding condition (Experiment 1). Young participants showed PM failures only when the 1-back task was added to the low-demanding condition. Older participants exhibited a marked decline, particularly in the working memory load condition.

CONCLUSIONS

These results suggest that even low-demanding prospective memory tasks are resource-consuming in old age, and that working memory efficiency, affected by the aging process, plays a crucial role in the successful accomplishment of PM actions.

Effects of Interruptions on Prospective Memory Performance in Anesthesiology

Interruptions have been associated with adverse events in healthcare. However, supporting studies are descriptive and atheoretical rather than explanatory, and they seldom show that interruptions compromise patient safety. Prospective memory may provide useful theoretical background. We analyzed video from a full-scale patient simulator for factors enhancing or inhibiting anesthesiologists' prospective memory performance. The critical task was to remember to cross check a unit of blood against the patient before administering the blood. All 12 participants were interrupted by the surgeon when the blood arrived. Only participants who self-initiated the retrieval (n = 3), or returned their full attention to the transfusion task and saw the blood bag label (n = 7), remembered the check. The result can be explained with findings from prospective memory literature.

Prospective memory or prospective attention: physiological and pharmacological support for an attentional model

Previous studies have reported that nicotine, a cholinergic agonist, could improve prospective memory (PM) - memory for a delayed intention - in healthy young adults. In the present study, we asked whether nicotine effects on PM performance were attributable to a drug-induced non-specific increase in arousal. Therefore, a double-blind, placebo-controlled study compared the effect of nicotine to the effect of an arousal manipulation on PM performance. All participants were non-smokers; half received 1 mg nicotine via a nasal spray and half received a matched placebo. Within these groups, half of the volunteers were exposed to hard anagrams and exhibited heightened tense arousal, while half of the volunteers were given easy anagrams and showed no change in arousal. These manipulations resulted in four conditions, placebo/low-arousal (n=12), placebo/high-arousal (n=10), nicotine/low-arousal (n=12), nicotine/high-arousal (n=13). All participants completed an ongoing lexical decision task while maintaining a PM intention (to make a separate, non-focal, response to certain items embedded within the ongoing task). When introduced separately, both nicotine and high tense arousal improved PM performance, but when combined, this improvement was eliminated. It is argued that both nicotine and high tense arousal increase attentional resources, specifically improving monitoring of the PM targets, but when combined they no longer produce beneficial effects. Additionally, given that nicotine exerted no effect on physiological or subjective measures of arousal, we conclude that the observed effects of nicotine and of arousal on PM performance are driven by different pharmacological mechanisms.

Transparent meta-analysis of prospective memory and aging

Prospective memory (ProM) refers to our ability to become aware of a previously formed plan at the right time and place. After two decades of research on prospective memory and aging, narrative reviews and summaries have arrived at widely different conclusions. One view is that prospective memory shows large age declines, larger than age declines on retrospective memory (RetM). Another view is that prospective memory is an exception to age declines and remains invariant across the adult lifespan. The present meta-analysis of over twenty years of research settles this controversy. It shows that prospective memory declines with aging and that the magnitude of age decline varies by prospective memory subdomain (vigilance, prospective memory proper, habitual prospective memory) as well as test setting (laboratory, natural). Moreover, this meta-analysis demonstrates that previous claims of no age declines in prospective memory are artifacts of methodological and conceptual issues afflicting prior research including widespread ceiling effects, low statistical power, age confounds, and failure to distinguish between various subdomains of prospective memory (e.g., vigilance and prospective memory proper).

Neural correlates of prospective memory across the lifespan

OVERVIEW

Behavioural data reveal an inverted U-shaped function in the efficiency of prospective memory from childhood to young adulthood to later adulthood. However, prior research has not directly compared processes contributing to age-related variation in prospective memory across the lifespan, hence it is unclear whether the same factors explain the 'rise and fall' of prospective remembering from childhood to later adulthood. The present study examined this question using a paradigm that allowed us to consider the behavioural and neural correlates of processes associated with the prospective and retrospective components of prospective memory.

METHODS

We compared 14 adolescents, 14 young adults, and 14 old adults in a paradigm where the prospective memory task was embedded in a semantic categorization task.

RESULTS

The behavioural data revealed an inverted U-shaped function with adolescents and old adults performing poorly relative to young adults. Analyses of the error data revealed that different processes may have contributed to failures of prospective memory in adolescents and older adults. This finding was supported by age differences in ERP-components for cue detection and post-retrieval processes. Additionally, source localization using LORETA revealed different patterns of neural recruitment for adolescents and older adults relative to younger adults.

CONCLUSION

Our findings demonstrate that adolescents and older adults show different patterns of behavioural errors and neural recruitment for successful prospective remembering indicating that different processes may contribute to the 'rise and fall' of prospective memory across the lifespan.

Delayed–Execute Prospective Memory Performance: The Effects of Age and Working Memory

This study follows the novel delayed-execute prospective memory paradigm, which involves briefly delaying the execution of an intended action, a task that has been shown to produce substantial age effects. During the ongoing task, sentences were presented, and participants had to answer reading-comprehension questions and general knowledge questions. In the prospective memory task, the participant was to press a key after the presentation of a specific cue in the sentences-but not before a subsequent phase of the ongoing task was reached. In contrast to previous studies using older participants taken from very broadly defined age ranges, this study examines development of delayed-execute prospective memory more precisely by examining a total of 4 age groups: a younger age group (age range = 22-31; n = 27), a young-old age group (age range = 60-69; n = 34), a middle-old age group (age range = 70-79; n = 31), and an old-old age group (age range = 80-91; n = 35). This study investigates the dependence of (age-related) delayed-execute prospective memory performance on working memory capacity by disrupting the phonological loop during the delay period as well as its dependence on neuropsychological processes such as inhibitory control and processing speed. The results show that (a) delayed-execute prospective memory particularly declines within the group of older participants, (b) delayed-execute prospective memory is diminished when working memory load is high during the delay period, and (c) age-related performance in delayed-execute prospective memory may be mediated by inhibitory control. The findings are discussed in the context of the frontal lobe hypothesis of cognitive aging.

Comparable effects of nicotine in smokers and nonsmokers on a prospective memory task

In a double-blind placebo-controlled study, we examined the effect of nicotine, a cholinergic agonist, on performance of a prospective memory (ProM) task in young adult volunteers. Volunteers were required to complete an ongoing lexical decision task while maintaining the ProM task (responding with a different button press to items containing particular target letters). Half of the volunteers were smokers, half were nonsmokers. Half of each group received a single dose (1 mg) of nicotine nasal spray before completing the task; the remaining volunteers received a matched inactive placebo spray. Nicotine improved performance on the ProM task when volunteers were able to devote resources to that task. Under a variant procedure, where volunteers completed a concurrent auditory monitoring task, ProM performance was impaired under nicotine. Results are discussed in terms of the resource model of ProM, and the arousal model of drug effects. The data suggest that ProM under the conditions tested here is a resource-needy process, and that nicotine can improve performance by increasing available resources. Increased working memory demands that encourage redirection of resources may impair ProM performance, but the conditions under which these deficits emerge depend upon the subjective allocation of resources across tasks, rather than resource availability per se.

Effects of aging and working memory demands on prospective memory

The current study used event-related brain potentials (ERPs) to examine the effects of aging, increasing the working memory demands of the ongoing activity, and a prospective memory load on the neural correlates of prospective remembering and target recognition. The behavioral data revealed that the success of prospective memory was sensitive to working memory load in younger, but not older, adults and that a prospective memory load had a greater effect on the performance of older adults than that of younger adults. The ERP data revealed age-related differences in the neural correlates of the detection of prospective cues, post-retrieval processes that support prospective memory, and target recognition. Our results support the hypothesis that there are age-related differences in the ability to recruit preparatory attentional processes that underlie prospective memory, and demonstrate that younger and older adults may recruit somewhat different neural generators to support prospective memory and working memory.

Predictors of cardiopulmonary resuscitation and automated external defibrillator skill retention

BACKGROUND

Few data exist regarding the retention of cardiopulmonary resuscitation (CPR) and automated external defibrillator (AED) skills over time in relationship to characteristics of lay volunteer responders, training, or risk of exposure to victims. The purpose of this study was to describe the characteristics associated with adequate CPR and AED skill retention.

METHODS AND RESULTS

Skill retention was tested 3 to 18 months (mean 6.9 +/- 3.5 months) after initial training. Instructors judged adequacy of performance of essential CPR or AED skills and provided an overall assessment (adequate/inadequate), which was used as the outcome. Data on 7261 laypersons trained in CPR (4358 also received AED training) in 24 sites across the United States and Canada were available from the Public Access Defibrillation (PAD) Trial. Characteristics of the volunteers, classes, and facilities were evaluated as predictors of performance adequacy. Adjusting for site, intervention assignment (CPR-only or CPR + AED), and time since initial training, volunteer characteristics associated with adequate CPR performance were age (OR 0.78 per 10-year increment), male sex (OR 1.44), minority (OR 0.62), married (OR 1.35), prior emergency experience (OR 1.66), prior CPR class (OR 1.68), prior advanced training (OR 1.59), and extracurricular CPR training (OR 1.91) (all P < .05). Characteristics associated with AED performance included age (OR 0.69), college education (OR 1.34), and native language other than English (OR 0.51) (all P < .05).

CONCLUSIONS

Certain subgroups of lay volunteers may need targeted outreach programs in CPR and AED use, classes with longer training time, more practice, or more intense retraining to maintain their CPR and/or AED skills.